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“How Malleable Are Cognitive Abilities? A Critical Perspective on Popular Brief Interventions”, Moreau 2021

2021-moreau.pdf: “How malleable are cognitive abilities? A critical perspective on popular brief interventions”⁠, David Moreau (2021-12-23; ⁠, ⁠, ; similar):

This review discusses evidence across a number of popular brief interventions designed to enhance cognitive abilities and suggests that these interventions often fail to elicit reliable improvements. Consequences of exaggerated claims are discussed, together with a call for constructive criticism when evaluating this body of research.

A number of popular research areas suggest that cognitive performance can be manipulated via relatively brief interventions. These findings have generated a lot of traction, given their inherent appeal to individuals and society. However, recent evidence indicates that cognitive abilities might not be as malleable as preliminary findings implied and that other more stable factors play an important role.

In this article, I provide a critical outlook on these trends of research, combining findings that have mainly remained segregated despite shared characteristics.

Specifically, I suggest that the purported cognitive improvements elicited by many interventions are not reliable, and that their ecological validity remains limited.

I conclude with a call for constructive skepticism when evaluating claims of generalized cognitive improvements following brief interventions.

[Keywords: behavioral interventions, cognitive improvements, brain plasticity⁠, genetics, intelligence]

“On the Working Memory of Humans and Great Apes: Strikingly Similar or Remarkably Different?”, Read et al 2021

“On the Working Memory of Humans and Great Apes: Strikingly Similar or Remarkably Different?”⁠, Dwight W. Read, Héctor M. Manrique, Michael J. Walker (2021-12-14; ⁠, ⁠, ; similar):

  • Data from natural settings and laboratories imply Pan working memory (WM) is 2 ± 1
  • WM increases until puberty but puberty occurs at half the age for Pan as for humans
  • Claims for extraordinary working memory in Pan are not supported by data
  • WM increase during hominin evolution parallels complexity increase in stone artifacts
  • Cumulative WM changes in Homo sapiens evolution led to qualitative cognitive changes

In this article we review publications relevant to addressing widely reported claims in both the academic and popular press that chimpanzees working memory (WM) is comparable to, if not exceeding, that of humans. WM is a complex multidimensional construct with strong parallels in humans to prefrontal cortex and cognitive development. These parallels occur in chimpanzees, but to a lesser degree.

We review empirical evidence and conclude that the size of WM in chimpanzees is 2 ± 1 versus Miller’s famous 7 ± 2 in humans. Comparable differences occur in experiments on chimpanzees relating to strategic and attentional WM subsystems. Regardless of the domain, chimpanzee WM performance is comparable to that of humans around the age of 4 or 5.

Next, we review evidence showing parallels among the evolution of WM capacity in hominins ancestral to Homo sapiens, the phylogenetic evolution of hominins leading to Homo sapiens, and evolution in the complexity of stone tool technology over this time period.

[Keywords: working memory, human evolution, cognitive evolution, comparative psychology, chimpanzee, hominin evolution, theory of mind, planning]

“Testing the Structure of Human Cognitive Ability Using Evidence Obtained from the Impact of Brain Lesions over Abilities”, Protzko & Colom 2021

2021-protzko.pdf: “Testing the structure of human cognitive ability using evidence obtained from the impact of brain lesions over abilities”⁠, John Protzko, Roberto Colom (2021-11-01; ⁠, ⁠, ; backlinks; similar):

  • Focal cortical lesions lead to local, not global, deficits.
  • Measurement models to explain the positive manifold are causal models with unique predictions going beyond model fit statistics.
  • Correlated factor, network, process sampling, mutualism, investment models, make causal predictions inconsistent with lesion evidence.
  • Hierarchical and bifactor models are consistent with the pattern of lesion effects, as well as possibly one form of bonds sampling models.
  • Future models and explanations of the positive manifold have to accommodate focal lesions leading to local not global deficits.

Here we examine 3 classes of models regarding the structure of human cognition: common cause models, sampling/​network models, and interconnected models. That disparate models can accommodate one of the most globally replicated psychological phenomena—namely, the positive manifold—is an extension of underdetermination of theory by data. Statistical fit indices are an insufficient and sometimes intractable method of demarcating between the theories; strict tests and further evidence should be brought to bear on understanding the potential causes of the positive manifold. The cognitive impact of focal cortical lesions allows testing the necessary causal connections predicted by competing models. This evidence shows focal cortical lesions lead to local, not global (across all abilities), deficits. Only models that can accommodate a deficit in a given ability without effects on other covarying abilities can accommodate focal lesion evidence. After studying how different models pass this test, we suggest bifactor models (class: common cause models) and bond models (class: sampling models) are best supported. In short, competing psychometric models can be informed when their implied causal connections and predictions are tested.

[Keywords: human intelligence, structural models⁠, causality, statistical model fit, cortical lesions]

[This would seem to explain the failure of dual n-back & WM training in general.

Training the specific ability of WM could only cause g increases in models with ‘upwards causation’ like hierarchical models or dynamic mutual causation like mutualism/​investment models; these are ruled out by the lesion literature which finds that physically-tiny lesions damage specific abilities but not g, and if decreasing a specific ability cannot decrease g, then it’s hard to see how increasing that ability could ever increase g. See also Lee et al 2019⁠.]

“Training Working Memory for 2 Years—No Evidence of Latent Transfer to Intelligence”, Watrin et al 2021

2022-watrin.pdf: “Training Working Memory for 2 Years—No Evidence of Latent Transfer to Intelligence”⁠, Luc Watrin, Oliver Wilhelm, Gizem Hülür (2021-03-22; similar):

Working memory (WM) training has been proposed as a promising intervention to enhance cognitive abilities, but convincing evidence for transfer to untrained abilities is lacking. Prevalent limitations of WM training studies include the narrow assessment of both WM and cognitive abilities, the analysis of manifest variables subject to measurement error, and training dosages too low to likely cause changes in the cognitive system.

To address these limitations, we conducted a 2-year longitudinal study to investigate the effects of working memory training on latent factors of working memory capacity, fluid intelligence and crystallized intelligence. 112 students initially attending 9th grade practiced a heterogeneous set of validated WM tasks on a bi-weekly basis. A control group of 113 students initially attending 9th grade participated in the pretest and posttest. Broad and prototypical measures of fluid and crystallized intelligence served as measures of nearer and far transfer.

We found substantial and reliable training effects on the practiced WM tasks, as well as on a latent WM factor constituted by them. However, no transfer of training effects to latent factors of fluid or crystallized intelligence were observed.

These results question the utility and validity of WM training as means of improving cognitive abilities.

[Keywords: cognitive training, intelligence, latent change score models, transfer effects, working memory]

“No Evidence for Expectation Effects in Cognitive Training Tasks”, Vodyanyk et al 2021

2021-vodyanyk.pdf: “No Evidence for Expectation Effects in Cognitive Training Tasks”⁠, Mariya Vodyanyk, Aaron Cochrane, Anna Corriveau, Zachary Demko, C. Shawn Green (2021-03-12; similar):

A great deal of recent empirical and theoretical work has examined whether it is possible to enhance cognitive functioning via behavioral (cognitive) training. While a growing body of research provides support for such a hypothesis, multiple critiques of the field have suggested that any positive findings in the field to date may be due to placebo effects, rather than reflecting “true” benefits of the training paradigms.

Here, in a series of 4 experiments, we sought to purposefully induce placebo effects of this type in cognitive training-style setup. We did so in multiple outcome domains (fluid intelligence; spatial skills), employed multiple types of “training” paradigms (classic cognitive training using the N-back working memory task; the video game Tetris) and critically, combined explicit verbal instructions that participants in some groups “should” expect to improve their performance after completing their training with associative learning “evidence” that such improvements were occurring (via manipulated task designs).

In no case, though, was a placebo effect observed.

These results collectively provide evidence against the contention that placebo effects are a major driver of positive outcomes previously attributed to cognitive training interventions.

[Keywords: cognitive training, expectation effects, placebo effects, behavioral interventions]

“3D Multiple Object Tracking or Adaptive Dual n-back Training Boosts Simple Verbal Working Memory Span but Not Multitasking Performance in Military Participants”, Vartanian et al 2021

2021-vartanian.pdf: “3D Multiple Object Tracking or Adaptive Dual n-back Training Boosts Simple Verbal Working Memory Span but Not Multitasking Performance in Military Participants”⁠, Oshin Vartanian, Tonya Stokes-Hendriks, Kristen King, Emma Rice, Sarah Forbes (2021-01-06; similar):

There is a growing literature demonstrating that a short regimen of NeuroTracker—a task that trains 3D multiple object tracking skills—can improve various aspects of cognition (attention, memory) and performance in regular and elite athletes. Vartanian et al 2016 extended the application of NeuroTracker to the military domain by demonstrating that it can result in gains in simple working memory (WM) span (verbal, visual, and matrix) in Canadian Special Forces members who trained under the experimenters’ supervision.

Here, we conducted a follow-up study to determine whether similar gains would accrue if general Canadian Armed Forces (CAF) members were to train unsupervised—a much more likely scenario within military contexts. We randomly assigned CAF members (n = 66) to one of the 3 conditions: (1) NeuroTracker, (2) adaptive dual n-back, or (3) passive control. Participants in the training conditions trained for 20 min per day on 10 separate days within a 2-week period. Before and after training, we administered simple WM span measures (verbal and matrix). To examine far transfer to a task drawing on executive functions, we also administered a multitasking paradigm that deploys 4 visual and auditory tasks in parallel, designed to evaluate operator performance and workload analogous to activities that aircraft crew perform in flight (Multi-Attribute Task Battery: MATB-II).

Participants in both training conditions improved on the trained task and exhibited gains in simple verbal WM span. No gains were observed on MATB-II. Our results demonstrate that self-administered training on NeuroTracker or the adaptive dual n-back task can lead to gains in simple verbal WM span but not in simple matrix WM span or multitasking. In other words, in relation to both NeuroTracker and adaptive dual n-back training, we observed near transfer but not far transfer. We discuss the implications for cognitive training interventions in military contexts.

[Keywords: cognitive training, brain training, working memory, multitasking, military]

“Brain Training Habits Are Not Associated With Generalized Benefits to Cognition: An Online Study of over 1000 'brain Trainers'”, Stojanoski et al 2020

2020-stojanoski.pdf: “Brain training habits are not associated with generalized benefits to cognition: An online study of over 1000 'brain trainers'”⁠, Bobby Stojanoski, Conor J. Wild, Michael E. Battista, Emily S. Nichols, Adrian M. Owen (2020-09-24; similar):

The foundational tenet of brain training is that general cognitive functioning can be enhanced by completing computerized games, a notion that is both intuitive and appealing. Moreover, there is strong incentive to improve our cognitive abilities, so much so that it has driven a billion-dollar industry. However, whether brain training can really produce these desired outcomes continues to be debated. This is, in part, because the literature is replete with studies that use ill-defined criteria for establishing transferable improvements to cognition, often using single training and outcome measures with small samples.

To overcome these limitations, we conducted a large-scale online study to examine whether practices and beliefs about brain training are associated with better cognition. We recruited a diverse sample of over 1000 participants, who had been using an assortment of brain training programs for up to 5 years. Cognition was assessed using multiple tests that measure attention, reasoning, working memory and planning.

We found no association between any measure of cognitive functioning and whether participants were currently ‘brain training’ or not, even for the most committed brain trainers. Duration of brain training also showed no relationship with any cognitive performance measure. This result was the same regardless of participant age, which brain training program they used, or whether they expected brain training to work.

Our results pose a substantial challenge for ‘brain training’ programs that purport to improve general cognitive functioning among the general population.

“Training and Transfer Effects of Long-term Memory Retrieval Training”, Ma et al 2020

2020-ma.pdf: “Training and transfer effects of long-term memory retrieval training”⁠, Xiaofeng Ma, Haobao Zhang, Xin Zhao, Aibao Zhou (2020-08-30; similar):

Long-term memory retrieval ability and working memory can share attention control ability. Based on cognitive plasticity, a hypothesis that cognitive training could improve long-term memory retrieval efficiency and that this could transfer to retrieval involving working memory was proposed.

60 undergraduates were randomly assigned to a group of training and an active control group; all the participants completed the same tasks in the same order before and after the training, the tasks included a long-term memory retrieval access task, an intelligence test, a switching task, a working memory updating task, a response inhibition task and an interference control task.

The statistics results indicate that cognitive training can improve long-term memory retrieval efficiency and has a transfer effect on working memory updating, interference control and switching ability, but not on response inhibition or intelligence.

This reveal the plasticity of long-term memory retrieval and its influence on working memory.

“The Role of Executive Functions in Socioeconomic Attainment Gaps: Results From a Randomized Controlled Trial”, Blakey et al 2020

2020-blakey.pdf: “The Role of Executive Functions in Socioeconomic Attainment Gaps: Results From a Randomized Controlled Trial”⁠, Emma Blakey, Danielle Matthews, Lucy Cragg, Jessica Buck, David Cameron, Ben Higgins, Lisa Pepper, Ellen Ridley et al (2020-02-06)

“Working Memory Training Does Not Enhance Older Adults' Cognitive Skills: A Comprehensive Meta-analysis”, Sala et al 2019

“Working memory training does not enhance older adults' cognitive skills: A comprehensive meta-analysis”⁠, Giovanni Sala, N. Deniz Aksayli, K. Semir Tatlidil, Yasuyuki Gondo, Fernand Gobet (2019-11; backlinks; similar):

  • Working memory (WM) training does not enhance older adults’ cognitive function.
  • The training slightly improves older adults’ performance in untrained memory tasks.
  • The same pattern of results is observed in younger adults.
  • The models exhibit a high degree of consistency; hence this literature is not noisy.

In the last two decades, considerable efforts have been devoted to finding a way to enhance cognitive function by cognitive training. To date, the attempt to boost broad cognitive functions in the general population has failed. However, it is still possible that some cognitive training regimens exert a positive influence on specific populations, such as older adults. In this meta-analytic review, we investigated the effects of working memory (WM) training on older adults’ cognitive skills. Three robust-variance-estimation meta-analyses (N = 2140, m = 43, and k = 698) were run to analyze the effects of the intervention on (a) the trained tasks, (b) near-transfer measures, and (c) far-transfer measures. While large effects were found for the trained tasks (g = 0.877), only modest (g = 0.274) and near-zero (g = 0.121) effects were obtained in the near-transfer and far-transfer meta-analyses, respectively. Publication-bias analysis provided adjusted estimates that were slightly lower. Moreover, when active control groups were implemented, the far-transfer effects were null (g = −0.008). Finally, the effects were highly consistent across studies (ie. low or null true heterogeneity), especially in the near-transfer and far-transfer models. While confirming the difficulty in obtaining transfer effects with cognitive training, these results corroborate recent empirical evidence suggesting that WM is not isomorphic with other fundamental cognitive skills such as fluid intelligence.

“The Cognitive Benefits of Learning Computer Programming: A Meta-analysis of Transfer Effects”, Scherer et al 2019

2019-scherer.pdf: “The cognitive benefits of learning computer programming: A meta-analysis of transfer effects”⁠, Ronny Scherer, Fazilat Siddiq, Bárbara Sánchez Viveros (2019-07-01; ; backlinks; similar):

Does computer programming teach students how to think? Learning to program computers has gained considerable popularity, and educational systems around the world are encouraging students in schools and even children in kindergartens to engage in programming activities. This popularity is based on the claim that learning computer programming improves cognitive skills, including creativity, reasoning, and mathematical skills.

In this meta-analysis, we tested this claim performing a 3-level, random-effects meta-analysis on a sample of 105 studies and 539 effect sizes. We found evidence for a moderate, overall transfer effect (g = 0.49, 95% CI [0.37, 0.61]) and identified a strong effect for near transfer (g = 0.75, 95% CI [0.39, 1.11]) and a moderate effect for far transfer (g = 0.47, 95% CI [0.35, 0.59]). Positive transfer to situations that required creative thinking, mathematical skills, and metacognition, followed by spatial skills and reasoning existed. School achievement and literacy, however, benefited the least from learning to program. Moderator analyses revealed statistically-significantly larger transfer effects for studies with untreated control groups than those with treated (active) control groups. Moreover, published studies exhibited larger effects than gray literature.

These findings shed light on the cognitive benefits associated with learning computer programming and contribute to the current debate surrounding the conceptualization of computer programming as a form of problem solving.

[Keywords: cognitive skills, computational thinking, computer programming, three-level meta-analysis, transfer of skills, passive control group inflation, publication bias]

Educational Impact and Implications Statement: In this meta-analysis, we tested the claim that learning how to program a computer improves cognitive skills even beyond programming. The results suggested that students who learned computer programming outperformed those who did not in programming skills and other cognitive skills, such as creative thinking, mathematical skills, metacognition, and reasoning. Learning computer programming has certain cognitive benefits for other domains.

Moderators: …Statistically-significantly higher effects occurred for published literature (g = 0.60, 95% CI [0.45, 0.75]) than for gray literature (g = 0.34, 95% CI[0.15, 0.52]; QM[1] = 4.67, p = 0.03).

Besides the publication status, only the type of treatment that control groups received (ie. treated vs. untreated) statistically-significantly explained Level 2 variance, QM(1) = 40.12, p < 0.001, R[^2^~2~]{.supsub} = 16.7%. More specifically, transfer effect sizes were statistically-significantly lower for studies including treated control groups (g = 0.16) than for studies including untreated control groups (g = 0.65). [0.65 / 0.16 = 400% bias].

Figure 2a: Funnel plot

“The Hype Cycle of Working Memory Training”, Redick 2019

“The Hype Cycle of Working Memory Training”⁠, Thomas S. Redick (2019-05-16; ; backlinks; similar):

Seventeen years and hundreds of studies after the first journal article on working memory training was published, evidence for the efficacy of working memory training is still wanting. Numerous studies show that individuals who repeatedly practice computerized working memory tasks improve on those tasks and closely related variants. Critically, although individual studies have shown improvements in untrained abilities and behaviors, systematic reviews of the broader literature show that studies producing large, positive findings are often those with the most methodological shortcomings. The current review discusses the past, present, and future status of working memory training, including consideration of factors that might influence working memory training and transfer efficacy.

“The Efficacy of Different Interventions to Foster Children’s Executive Function Skills: A Series of Meta-Analyses”, Takacs & Kassai 2019

2019-takacs.pdf: “The Efficacy of Different Interventions to Foster Children’s Executive Function Skills: A Series of Meta-Analyses”⁠, Zsofia K. Takacs, Reka Kassai (2019-01-01)

“Suggestion of Cognitive Enhancement Improves Emotion Regulation”, Long et al 2019

2019-long.pdf: “Suggestion of cognitive enhancement improves emotion regulation”⁠, Quanshan Long, Na Hu, Hanxiao Li, Yi Zhang, Jiajin Yuan, Antao Chen (2019-01-01; backlinks)

“A Meta-analysis of the Experimental Evidence on the Near-transfer and Far-transfer Effects among Children’s Executive Function Skills”, Kassai et al 2019

2019-kassai.pdf: “A meta-analysis of the experimental evidence on the near-transfer and far-transfer effects among children’s executive function skills”⁠, Reka Kassai, Judit Futo, Zsolt Demetrovics, Zsofia K. Takacs (2019; backlinks; similar):

In the present meta-analysis we examined the near-transfer and far-transfer effects of training components of children’s executive functions skills: working memory, inhibitory control, and cognitive flexibility.

We found a statistically-significant near-transfer effect (g⁺ = 0.44, k = 43, p < 0.001) showing that the interventions in the primary studies were successful in training the targeted components. However, we found no convincing evidence of far-transfer (g⁺ = 0.11, k = 17, p = 0.11). That is, training a component did not have a statistically-significant effect on the untrained components.

By showing the absence of benefits that generalize beyond the trained components, we question the practical relevance of training specific executive function skills in isolation. Furthermore, the present results might explain the absence of far-transfer effects of working memory training on academic skills (Melby-Lervåg & Hulme 2013⁠; Sala & Gobet 2017).

“Targeted Training: Converging Evidence against the Transferable Benefits of Online Brain Training on Cognitive Function”, Stojanoski et al 2018

2018-stojanoski.pdf: “Targeted training: Converging evidence against the transferable benefits of online brain training on cognitive function”⁠, Bobby Stojanoski, Kathleen M. Lyons, Alexandra A. A. Pearce, Adrian M. Owen (2018-01-01)

“Cognitive Training Does Not Enhance General Cognition”, Sala et al 2018

2018-sala.pdf: “Cognitive Training Does Not Enhance General Cognition”⁠, Giovanni Sala, Fern, Gobet (2018-01-01)

“Effects Of TDCS Dosage On Working Memory In Healthy Participants”, Nikolin et al 2017

“Effects Of tDCS Dosage On Working Memory In Healthy Participants”⁠, Stevan Nikolin, Donel Martin, Colleen K. Loo, Tjeerd W. Boonstra (2017-09-22; backlinks; similar):

Background: Transcranial direct current stimulation (tDCS) has been found to improve working memory (WM) performance in healthy participants following a single session. However, results are mixed and the overall effect size is small. Interpretation of these results is confounded by heterogeneous study designs, including differences in tDCS dose (current intensity) and sham conditions used.

Aims: We systematically investigated the effect of tDCS dose on working memory using behavioural and neurophysiological outcomes.

Methods: In a single-blind parallel group design, 100 participants were randomised across five groups to receive 15 minutes of bifrontal tDCS at different current intensities (2mA, 1mA, and three sham tDCS conditions at 0.034mA, 0.016mA, or 0mA). EEG activity was acquired while participants performed a WM task prior to, during, and following tDCS. Response time, accuracy and an event-related EEG component (P3) were evaluated.

Results: We found no statistically-significant differences in response time or performance accuracy between current intensities. The P3 amplitude was statistically-significantly lower in the 0mA condition compared to the 0.034mA, 1mA and 2mA tDCS conditions. Changes in WM accuracy were moderately correlated with changes in the P3 amplitude following tDCS compared to baseline levels (r = 0.34).

Conclusions: Working memory was not statistically-significantly altered by tDCS, regardless of dose. The P3 amplitude showed that stimulation at 1mA, 2mA and a sham condition (0.034mA) had biological effects, with the largest effect size for 1mA stimulation. These findings indicate higher sensitivity of neurophysiological outcomes to tDCS and suggests that sham stimulation previously considered inactive may alter neuronal function.

“Terminal Latency”, Luu 2017

“Terminal Latency”⁠, Dan Luu (2017-07-18; ; backlinks; similar):

These graphs show the distribution of latencies for each terminal. The y-axis has the latency in milliseconds. The x-axis is the percentile (eg. 50 means represents 50%-ile keypress ie. the median keypress). Measurements are with macOS unless otherwise stated. The graph on the left is when the machine is idle, and the graph on the right is under load. If we just look at median latencies, some setups don’t look too bad— and emacs-eshell are at roughly 5ms unloaded, small enough that many people wouldn’t notice. But most terminals (st, alacritty, hyper, and iterm2) are in the range where you might expect people to notice the additional latency even when the machine is idle. If we look at the tail when the machine is idle, say the 99.9%-ile latency, every terminal gets into the range where the additional latency ought to be perceptible, according to studies on user interaction. For reference, the internally generated keypress to GPU memory trip for some terminals is slower than the time it takes to send a packet from Boston to Seattle and back, about 70ms.

…Most terminals have enough latency that the user experience could be improved if the terminals concentrated more on latency and less on other features or other aspects of performance. However, when I search for terminal benchmarks, I find that terminal authors, if they benchmark anything, benchmark the speed of sinking stdout or memory usage at startup. This is unfortunate because most “low performance” terminals can already sink stdout many orders of magnitude faster than humans can keep up with, so further optimizing stdout throughput has a relatively small impact on actual user experience for most users. Likewise for reducing memory usage when an idle terminal uses 0.01% of the memory on my old and now quite low-end laptop. If you work on a terminal, perhaps consider relatively more latency and interactivity (eg. responsiveness to ^C) optimization and relatively less throughput and idle memory usage optimization.

“Web Bloat”, Luu 2017

“Web Bloat”⁠, Dan Luu (2017-02-08; ; backlinks; similar):

A couple years ago, I took a road trip from Wisconsin to Washington and mostly stayed in rural hotels on the way. I expected the internet in rural areas too sparse to have cable internet to be slow, but I was still surprised that a large fraction of the web was inaccessible. Some blogs with lightweight styling were readable, as were pages by academics who hadn’t updated the styling on their website since 1995. But very few commercial websites were usable (other than Google). When I measured my connection, I found that the bandwidth was roughly comparable to what I got with a 56k modem in the 90s. The latency and packet loss were substantially worse than the average day on dialup: latency varied between 500ms and 1000ms and packet loss varied between 1% and 10%. Those numbers are comparable to what I’d see on dialup on a bad day.

Despite my connection being only a bit worse than it was in the 90s, the vast majority of the web wouldn’t load…When Microsoft looked at actual measured connection speeds, they found that half of Americans don’t have broadband speed. Heck, AOL had 2 million dial-up subscribers in 2015, just AOL alone. Outside of the U.S., there are even more people with slow connections. I recently chatted with Ben Kuhn, who spends a fair amount of time in Africa, about his internet connection:

I’ve seen ping latencies as bad as ~45 sec and packet loss as bad as 50% on a mobile hotspot in the evenings from Jijiga, Ethiopia. (I’m here now and currently I have 150ms ping with no packet loss but it’s 10am). There are some periods of the day where it ~never gets better than 10 sec and ~10% loss. The internet has gotten a lot better in the past ~year; it used to be that bad all the time except in the early mornings.

…Let’s load some websites that programmers might frequent with a variety of simulated connections to get data on page load times…The timeout for tests was 6 minutes; anything slower than that is listed as FAIL. Pages that failed to load are also listed as FAIL. A few things that jump out from the table are:

  1. A large fraction of the web is unusable on a bad connection. Even on a good (0% packet loss, no ping spike) dialup connection, some sites won’t load…If you were to look at the 90%-ile results, you’d see that most pages fail to load on dialup and the “Bad” and “😱” connections are hopeless for almost all sites.
  2. Some sites will use a lot of data!

…The flaw in the “page weight doesn’t matter because average speed is fast” [claim] is that if you average the connection of someone in my apartment building (which is wired for 1Gbps internet) and someone on 56k dialup, you get an average speed of 500 Mbps. That doesn’t mean the person on dialup is actually going to be able to load a 5MB website. The average speed of 3.9 Mbps comes from a 2014 Akamai report, but it’s just an average. If you look at Akamai’s 2016 report, you can find entire countries where more than 90% of IP addresses are slower than that!..”Use bcrypt” has become the mantra for a reasonable default if you’re not sure what to do when storing passwords. The web would be a nicer place if “use webpagetest” caught on in the same way. It’s not always the best tool for the job, but it sure beats the current defaults.

“Placebo Effects in Cognitive Training”, Foroughi et al 2016

2016-foroughi.pdf: “Placebo effects in cognitive training”⁠, Cyrus K. Foroughi, Samuel S. Monfort, Martin Paczynski, Patrick E. McKnight, P. M. Greenwood (2016-07-05; backlinks; similar):

Placebo effects pose problems for some intervention studies, particularly those with no clearly identified mechanism. Cognitive training falls into that category, and yet the role of placebos in cognitive interventions has not yet been critically evaluated. Here, we show clear evidence of placebo effects after a brief cognitive training routine that led to substantial fluid intelligence gains. Our goal is to emphasize the importance of ruling out alternative explanations before attributing the effect to interventions. Based on our findings, we recommend that researchers account for placebo effects before claiming treatment effects.

Although a large body of research shows that general cognitive ability is heritable and stable in young adults, there is recent evidence that fluid intelligence can be heightened with cognitive training. Many researchers, however, have questioned the methodology of the cognitive-training studies reporting improvements in fluid intelligence: specifically, the role of placebo effects. W

e designed a procedure to intentionally induce a placebo effect via overt recruitment in an effort to evaluate the role of placebo effects in fluid intelligence gains from cognitive training. Individuals who self-selected into the placebo group by responding to a suggestive flyer showed improvements after a single, 1-h session of cognitive training that equates to a 5-point to 10-point increase on a standard IQ test. Controls responding to a non-suggestive flyer showed no improvement.

These findings provide an alternative explanation for effects observed in the cognitive-training literature and the brain-training industry, revealing the need to account for confounds in future research.

…We also observed differences between groups for scores on the Theories of Intelligence scale, which measures beliefs regarding the malleability of intelligence (34). The participants in the placebo group reported substantially higher scores on this index compared with controls [B = 14.96, SE = 1.93, t(48) = 7.75, p < 0.0001, d = 2.15], indicating a greater confidence that intelligence is malleable. These findings indicate that our manipulation via recruitment flyer produced statistically-significantly different groups with regard to expectancy. We did not detect differences in Need for Cognition scores (41) [B = 0.56, SE = 5.67, t(48) = 0.10, p = 0.922] (Figure 3). Together, these results support the interpretation that participants self-selected into groups based on differing expectations.

“Effects of Anodal Transcranial Direct Current Stimulation on Working Memory: A Systematic Review and Meta-Analysis of Findings From Healthy and Neuropsychiatric Populations”, Hill et al 2016

2015-hill.pdf: “Effects of Anodal Transcranial Direct Current Stimulation on Working Memory: A Systematic Review and Meta-Analysis of Findings From Healthy and Neuropsychiatric Populations”⁠, Aron T. Hill, Paul B. Fitzgerald, Kate E. Hoy (2016-03; backlinks; similar):

  • We performed a meta-analysis investigating working memory (WM) enhancement with anodal tDCS (a-tDCS) in healthy and neuropsychiatric cohorts.
  • We examined both online and offline effects of stimulation.
  • We explored the role of current density and stimulation duration on WM performance.
  • Our results demonstrate mixed effects of a-tDCS on WM performance.
  • A-tDCS enhanced offline WM reaction times in healthy populations, with a trend towards improvement for accuracy, while online WM accuracy in neuropsychiatric populations was improved. No other statistically-significant results were obtained.
  • We provide limited evidence that higher current densities and longer stimulation durations might be more effective at modulating WM.

Background: Several studies have trialed anodal transcranial direct current stimulation (a-tDCS) for the enhancement of working memory (WM) in both healthy and neuropsychiatric populations. However, the efficacy of this technique remains to be clearly established.

Objective: This review provides a quantitative synthesis of the published literature investigating the effects of a-tDCS, compared to sham, on WM, as assessed using the n-back, Sternberg and digit-span tasks. We also separated results from tasks performed ‘online’ (during stimulation) and ‘offline’ (following stimulation). The secondary aim was to assess for any additional effects of current density and stimulation duration.

Methods: Comprehensive literature searches were performed using MEDLINE⁠, Embase⁠, PsycINFO⁠, CENTRAL and Scopus from July 1998 to June 2014.

Results: In healthy cohorts, a-tDCS produced a trend towards improvement for offline WM accuracy (p = 0.05) and a small, but statistically-significant improvement in reaction time (p = 0.04); however, no statistically-significant effects were observed for online tasks (accuracy [p = 0.29], reaction time [p = 0.42]). In the neuropsychiatric cohort, a-tDCS statistically-significantly improved accuracy for online (p = 0.003), but not offline (p = 0.87) tasks, and no effect was seen for either online (p = 0.20) or offline (p = 0.49) reaction times. Secondary analyses controlling for current density and stimulation duration provided limited support for the role of these factors in influencing a-tDCS efficacy.

Conclusions: This review provides some evidence of a beneficial effect of a-tDCS on WM performance. However, the small effect sizes obtained, coupled with non-significant effects on several analyses require cautious interpretation and highlight the need for future research aimed at investigating more optimised stimulation approaches.

[Keywords: transcranial direct current stimulation (tDCS), cognition, working memory, dorsolateral prefrontal cortex, psychiatry]

“Training and Transfer Effects of n-back Training for Brain-injured and Healthy Subjects”, Lindeløv et al 2016

2016-lindelov.pdf: “Training and transfer effects of n-back training for brain-injured and healthy subjects”⁠, Jonas Kristoffer Lindeløv, Jonas Olsen Dall, Casper Daniel Kristensen, Marie Holt Aagesen, Stine Almgren Olsen et al (2016-02-16; backlinks; similar):

Working memory impairments are prevalent among patients with acquired brain injury (ABI). Computerised training targeting working memory has been researched extensively using samples from healthy populations but this field remains isolated from similar research in ABI patients.

We report the results of an actively controlled randomised controlled trial in which 17 patients and 18 healthy subjects completed training on an n-back task.

The healthy group had superior improvements on both training tasks (SMD = 6.1 and 3.3) whereas the ABI group improved much less (SMD = 0.5 and 1.1). Neither group demonstrated transfer to untrained tasks.

We conclude that computerised training facilitates improvement of specific skills rather than high-level cognition in healthy and ABI subjects alike. The acquisition of these specific skills seems to be impaired by brain injury. The most effective use of computer-based cognitive training may be to make the task resemble the targeted behaviour(s) closely in order to exploit the stimulus-specificity of learning.

[Keywords: cognitive rehabilitation, n-back, cognitive transfer, computer]

“A Simultaneous Examination of Two Forms of Working Memory Training: Evidence for near Transfer Only”, Minear et al 2016

2016-minear.pdf: “A simultaneous examination of two forms of working memory training: Evidence for near transfer only”⁠, Meredith Minear, Faith Brasher, Claudia Brandt Guerrero, Mandy Brasher, Andrew Moore, Joshua Sukeena (2016-01-01; backlinks)

“Neural Correlates of Training and Transfer Effects in Working Memory in Older Adults”, Heinzel et al 2016

2016-heinzel.pdf: “Neural correlates of training and transfer effects in working memory in older adults”⁠, Stephan Heinzel, Robert C. Lorenz, Patricia Pelz, Andreas Heinz, Henrik Walter, Norbert Kathmann, Michael A. Rapp et al (2016-01-01; backlinks)

“3D Multiple Object Tracking Boosts Working Memory Span: Implications for Cognitive Training in Military Populations”, Vartanian et al 2016

2016-vartanian.pdf: “3D Multiple Object Tracking Boosts Working Memory Span: Implications for Cognitive Training in Military Populations”⁠, Oshin Vartanian, Lori Coady, Kristen Blackler (2016; backlinks; similar):

Recently, there has been much theoretical and applied interest in the prospects of cognitive training for improving cognition. NeuroTracker is a relatively recent training device for improving dynamic attention in athletes by training 3D multiple-object tracking skills.

We examined its effectiveness for improving working memory (WM) span in members of the Canadian Armed Forces (CAF) by randomly assigning participants to the experimental (NeuroTracker), active control (adaptive dual n-back task), or passive control (no contact) conditions. NeuroTracker training resulted in statistically-significant gains in verbal, visual, and matrix span. No gain was observed in the active or passive control group.

These results suggest that NeuroTracker could be an useful training tool for increasing WM span in military samples. Future studies could examine the effects of NeuroTracker training on militarily relevant performance measures that draw on WM span.

[Keywords: working memory, cognitive training, attention]

“Increased Training Complexity Reduces the Effectiveness of Brief Working Memory Training: Evidence from Short-term Single and Dual n-back Training Interventions”, Küper & Karbach 2015

2015-kuper.pdf: “Increased training complexity reduces the effectiveness of brief working memory training: evidence from short-term single and dual n-back training interventions”⁠, Kristina Küper, Julia Karbach (2015-12-07; backlinks; similar):

N-back training has recently come under intense scientific scrutiny due to reports of training-related improvements in general fluid intelligence⁠. As of yet, relatively little is known about the effects of short-term n-back training interventions, however.

In a pretest-training-posttest design, we compared brief dual and single n-back training regimen in terms of training gains and transfer effects relative to a passive control group.

Transfer effects indicated that, in the short-term, single n-back training may be the more effective training task: At the short training duration we employed, neither training group showed far transfer to specific task switch costs, Stroop inhibition costs or matrix reasoning indexing fluid intelligence. Yet, both types of training resulted in a reduction of general task switch costs indicating improved cognitive control during the sustained maintenance of competing task sets. Single but not dual n-back training additionally yielded near transfer to an untrained working memory updating task.

[Keywords: dual n-back training, single n-back training, short-term training, working memory training, transfer effects]

“The Effect of γ-tACS on Working Memory Performance in Healthy Controls”, Hoy et al 2015

2015-hoy.pdf: “The effect of γ-tACS on working memory performance in healthy controls”⁠, Kate E. Hoy, Neil Bailey, Sara Arnold, Kirstyn Windsor, Joshua John, Zafiris J. Daskalakis, Paul B. Fitzgerald et al (2015-01-01; ; backlinks)

“Are Adoption Gains on the G Factor? A Meta-analysis”, Nijenhuis et al 2015

2015-tenijenhuis.pdf: “Are adoption gains on the g factor? A meta-analysis”⁠, Jan te Nijenhuis, Birthe Jongeneel-Grimen, Elijah L. Armstrong (2015-01-01; ⁠, ; backlinks)

“The Environment in Raising Early Intelligence: A Meta-analysis of the Fadeout Effect”, Protzko 2015

2015-protzko.pdf: “The environment in raising early intelligence: A meta-analysis of the fadeout effect”⁠, John Protzko (2015-01-01; ; backlinks)

“Combining TDCS and Working Memory Training to Down Regulate State Rumination: A Single-Session Double Blind Sham-Controlled Trial”, Putter et al 2015

2015-putter.pdf: “Combining tDCS and Working Memory Training to Down Regulate State Rumination: A Single-Session Double Blind Sham-Controlled Trial”⁠, Laura M. S. De Putter, Marie-Anne Vanderhasselt, Chris Baeken, Rudi Raedt, Ernst H. W. Koster (2015-01-01; backlinks)

“Effects of Acute Transcranial Direct Current Stimulation in Hot and Cold Working Memory Tasks in Healthy and Depressed Subjects”, Moreno et al 2015

2015-moreno.pdf: “Effects of acute transcranial direct current stimulation in hot and cold working memory tasks in healthy and depressed subjects”⁠, Marina L. Moreno, Marie-Anne Vanderhasselt, Andre F. Carvalho, Adriano H. Moffa, Paulo A. Lotufo, Isabela M. Benseñor et al (2015-01-01; backlinks)

“A General Factor of Intelligence Fails to Account for Changes in Tests’ Scores After Cognitive Practice: A Longitudinal Multi-group Latent-variable Study”, Estrada et al 2015

2015-estrada.pdf: “A general factor of intelligence fails to account for changes in tests’ scores after cognitive practice: A longitudinal multi-group latent-variable study”⁠, Eduardo Estrada, Emilio Ferrer, Francisco J. Abad, Francisco J. Román, Roberto Colom (2015-01-01; backlinks)

“Fluid Intelligence and Working Memory Capacity: Is the Time for Working on Intelligence Problems Relevant for Explaining Their Large Relationship?”, Colom et al 2015

2015-colom.pdf: “Fluid intelligence and working memory capacity: Is the time for working on intelligence problems relevant for explaining their large relationship?”⁠, Roberto Colom, Jesús Privado, Luis F. García, Eduardo Estrada, Lara Cuevas, Pei-Chun Shih (2015-01-01; backlinks)

“The Broad Factor of Working Memory Is Virtually Isomorphic to Fluid Intelligence Tested under Time Pressure”, Chuderski 2015

2015-chuderski.pdf: “The broad factor of working memory is virtually isomorphic to fluid intelligence tested under time pressure”⁠, Adam Chuderski (2015-01-01; backlinks)

“Do We Really Become Smarter When Our Fluid-Intelligence Test Scores Improve?”, Hayes et al 2015

“Do We Really Become Smarter When Our Fluid-Intelligence Test Scores Improve?”⁠, Taylor R. Hayes, Alexander A. Petrov, Per B. Sederberg (2015; ; backlinks; similar):

Recent reports of training-induced gains on fluid intelligence tests have fueled an explosion of interest in cognitive training-now a billion-dollar industry. The interpretation of these results is questionable because score gains can be dominated by factors that play marginal roles in the scores themselves, and because intelligence gain is not the only possible explanation for the observed control-adjusted far transfer across tasks. Here we present novel evidence that the test score gains used to measure the efficacy of cognitive training may reflect strategy refinement instead of intelligence gains. A novel scanpath analysis of eye movement data from 35 participants solving Raven’s Advanced Progressive Matrices on two separate sessions indicated that 1⁄3rd of the variance of score gains could be attributed to test-taking strategy alone, as revealed by characteristic changes in eye-fixation patterns. When the strategic contaminant was partialled out, the residual score gains were no longer significant. These results are compatible with established theories of skill acquisition suggesting that procedural knowledge tacitly acquired during training can later be utilized at posttest. Our novel method and result both underline a reason to be wary of purported intelligence gains, but also provide a way forward for testing for them in the future.

“Computerized Cognitive Training in Cognitively Healthy Older Adults: A Systematic Review and Meta-Analysis of Effect Modifiers”, Lampit et al 2014

“Computerized Cognitive Training in Cognitively Healthy Older Adults: A Systematic Review and Meta-Analysis of Effect Modifiers”⁠, Amit Lampit, Harry Hallock, Michael Valenzuela (2014-09-29; backlinks; similar):

Background: New effective interventions to attenuate age-related cognitive decline are a global priority. Computerized cognitive training (CCT) is believed to be safe and can be inexpensive, but neither its efficacy in enhancing cognitive performance in healthy older adults nor the impact of design factors on such efficacy has been systematically analyzed. Our aim therefore was to quantitatively assess whether CCT programs can enhance cognition in healthy older adults, discriminate responsive from nonresponsive cognitive domains, and identify the most salient design factors.

Methods and Findings: We systematically searched MEDLINE⁠, Embase⁠, and PsycINFO for relevant studies from the databases’ inception to 9 July 2014. Eligible studies were randomized controlled trials investigating the effects of ≥4 h of CCT on performance in neuropsychological tests in older adults without dementia or other cognitive impairment. Fifty-two studies encompassing 4,885 participants were eligible. Intervention designs varied considerably, but after removal of one outlier, heterogeneity across studies was small (I2 = 29.92%). There was no systematic evidence of publication bias. The overall effect size (Hedges’ g⁠, random effects model) for CCT versus control was small and statistically-significant, g = 0.22 (95% CI 0.15 to 0.29). Small to moderate effect sizes were found for nonverbal memory, g = 0.24 (95% CI 0.09 to 0.38); verbal memory, g = 0.08 (95% CI 0.01 to 0.15); working memory (WM), g = 0.22 (95% CI 0.09 to 0.35); processing speed, g = 0.31 (95% CI 0.11 to 0.50); and visuospatial skills, g = 0.30 (95% CI 0.07 to 0.54). No statistically-significant effects were found for executive functions and attention. Moderator analyses revealed that home-based administration was ineffective compared to group-based training, and that more than three training sessions per week was ineffective versus three or fewer. There was no evidence for the effectiveness of WM training, and only weak evidence for sessions less than 30 min. These results are limited to healthy older adults, and do not address the durability of training effects.

Conclusions: CCT is modestly effective at improving cognitive performance in healthy older adults, but efficacy varies across cognitive domains and is largely determined by design choices. Unsupervised at-home training and training more than three times per week are specifically ineffective. Further research is required to enhance efficacy of the intervention.

“Are Headstart Gains on the G Factor? A Meta-analysis”, Nijenhuis et al 2014

2014-tenijenhuis.pdf: “Are Headstart gains on the g factor? A meta-analysis”⁠, Jan te Nijenhuis, Birthe Jongeneel-Grimen, Emil O. W. Kirkegaard (2014-01-01; ; backlinks)

“Transcranial Direct Current Stimulation Based Metaplasticity Protocols in Working Memory”, Carvalho et al 2014

2014-carvalho.pdf: “Transcranial Direct Current Stimulation Based Metaplasticity Protocols in Working Memory”⁠, Sandra Carvalho, Paulo S. Boggio, Óscar F. Gonçalves, Ana Rita Vigário, Marisa Faria, Soraia Silva, Gabriel Gaudencio do Rego et al (2014-01-01; backlinks)

“An Opportunity Cost Model of Subjective Effort and Task Performance”, Kurzban et al 2013-page-14

2013-kurzban.pdf#page=14: “An opportunity cost model of subjective effort and task performance”⁠, Robert Kurzban, Angela Duckworth, Joseph W. Kable, Justus Myers (2013-12-04; ⁠, ⁠, ⁠, ; backlinks):

Why does performing certain tasks cause the aversive experience of mental effort and concomitant deterioration in task performance? One explanation posits a physical resource that is depleted over time. We propose an alternative explanation that centers on mental representations of the costs and benefits associated with task performance. Specifically, certain computational mechanisms, especially those associated with executive function, can be deployed for only a limited number of simultaneous tasks at any given moment. Consequently, the deployment of these computational mechanisms carries an opportunity cost—that is, the next-best use to which these systems might be put. We argue that the phenomenology of effort can be understood as the felt output of these cost/​benefit computations. In turn, the subjective experience of effort motivates reduced deployment of these computational mechanisms in the service of the present task. These opportunity cost representations, then, together with other cost/​benefit calculations, determine effort expended and, everything else equal, result in performance reductions. In making our case for this position, we review alternative explanations for both the phenomenology of effort associated with these tasks and for performance reductions over time. Likewise, we review the broad range of relevant empirical results from across sub-disciplines, especially psychology and neuroscience. We hope that our proposal will help to build links among the diverse fields that have been addressing similar questions from different perspectives, and we emphasize ways in which alternative models might be empirically distinguished.

“An Opportunity Cost Model of Subjective Effort and Task Performance”, Kurzban et al 2013

2013-kurzban.pdf: “An opportunity cost model of subjective effort and task performance”⁠, Robert Kurzban, Angela Duckworth, Joseph W. Kable, Justus Myers (2013-12-04; ⁠, ⁠, ⁠, ; backlinks):

Why does performing certain tasks cause the aversive experience of mental effort and concomitant deterioration in task performance? One explanation posits a physical resource that is depleted over time. We propose an alternative explanation that centers on mental representations of the costs and benefits associated with task performance. Specifically, certain computational mechanisms, especially those associated with executive function, can be deployed for only a limited number of simultaneous tasks at any given moment. Consequently, the deployment of these computational mechanisms carries an opportunity cost—that is, the next-best use to which these systems might be put. We argue that the phenomenology of effort can be understood as the felt output of these cost/​benefit computations. In turn, the subjective experience of effort motivates reduced deployment of these computational mechanisms in the service of the present task. These opportunity cost representations, then, together with other cost/​benefit calculations, determine effort expended and, everything else equal, result in performance reductions. In making our case for this position, we review alternative explanations for both the phenomenology of effort associated with these tasks and for performance reductions over time. Likewise, we review the broad range of relevant empirical results from across sub-disciplines, especially psychology and neuroscience. We hope that our proposal will help to build links among the diverse fields that have been addressing similar questions from different perspectives, and we emphasize ways in which alternative models might be empirically distinguished.

“Creatine Cognition Meta-analysis”, Branwen 2013

Creatine: “Creatine Cognition Meta-analysis”⁠, Gwern Branwen (2013-09-06; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Does creatine increase cognitive performance? Maybe for vegetarians but probably not.

I attempt to meta-analyze conflicting studies about the cognitive benefits of creatine supplementation. The wide variety of psychological measures by uniformly small studies hampers any aggregation. 3 studies measured IQ and turn in a positive result, but suggestive of vegetarianism causing half the benefit. Discussions indicate that publication bias is at work. Given the variety of measures, small sample sizes, publication bias, possible moderators, and small-study biases, any future creatine studies should use the most standard measures of cognitive function like RAPM in a reasonably large pre-registered experiment.

“The Pervasive Problem With Placebos in Psychology: Why Active Control Groups Are Not Sufficient to Rule Out Placebo Effects”, Boot et al 2013

2013-boot.pdf: “The Pervasive Problem With Placebos in Psychology: Why Active Control Groups Are Not Sufficient to Rule Out Placebo Effects”⁠, Walter R. Boot, Daniel J. Simons, Cary Stothart, Cassie Stutts (2013-07-09; backlinks; similar):

To draw causal conclusions about the efficacy of a psychological intervention, researchers must compare the treatment condition with a control group that accounts for improvements caused by factors other than the treatment.

Using an active control helps to control for the possibility that improvement by the experimental group resulted from a placebo effect. Although active control groups are superior to “no-contact” controls, only when the active control group has the same expectation of improvement as the experimental group can we attribute differential improvements to the potency of the treatment. Despite the need to match expectations between treatment and control groups, almost no psychological interventions do so.

This failure to control for expectations is not a minor omission—it is a fundamental design flaw that potentially undermines any causal inference. We illustrate these principles with a detailed example from the video-game-training literature showing how the use of an active control group does not eliminate expectation differences. The problem permeates other interventions as well, including those targeting mental health, cognition, and educational achievement.

Fortunately, measuring expectations and adopting alternative experimental designs makes it possible to control for placebo effects, thereby increasing confidence in the causal efficacy of psychological interventions.

[Keywords: intervention design, research methods, placebo effect, demand characteristics]

“Failure of Working Memory Training to Enhance Cognition or Intelligence”, Thompson et al 2013

“Failure of Working Memory Training to Enhance Cognition or Intelligence”⁠, Todd W. Thompson, Michael L. Waskom, Keri-Lee A. Garel, Carlos Cardenas-Iniguez, Gretchen O. Reynolds et al (2013-05-22; backlinks; similar):

Fluid intelligence is important for successful functioning in the modern world, but much evidence suggests that fluid intelligence is largely immutable after childhood. Recently, however, researchers have reported gains in fluid intelligence after multiple sessions of adaptive working memory training in adults. The current study attempted to replicate and expand those results by administering a broad assessment of cognitive abilities and personality traits to young adults who underwent 20 sessions of an adaptive dual n-back working memory training program and comparing their post-training performance on those tests to a matched set of young adults who underwent 20 sessions of an adaptive attentional tracking program. Pre-training and post-training measurements of fluid intelligence, standardized intelligence tests, speed of processing, reading skills, and other tests of working memory were assessed. Both training groups exhibited substantial and specific improvements on the trained tasks that persisted for at least 6 months post-training, but no transfer of improvement was observed to any of the non-trained measurements when compared to a third untrained group serving as a passive control. These findings fail to support the idea that adaptive working memory training in healthy young adults enhances working memory capacity in non-trained tasks, fluid intelligence, or other measures of cognitive abilities.

“Is It the Music or Is It Selection Bias? A Nationwide Analysis of Music and Non-Music Students’ SAT Scores”, Elpus 2013

2013-elpus.pdf: “Is It the Music or Is It Selection Bias? A Nationwide Analysis of Music and Non-Music Students’ SAT Scores”⁠, Kenneth Elpus (2013-05-21; ⁠, ; backlinks; similar):

This study examined the college entrance examination scores of music and non-music students in the United States, drawing data from the restricted-use data set of the Education Longitudinal Study of 2002 (ELS), a nationally representative education study (n = 15,630) conducted by the National Center for Education Statistics. Analyses of high school transcript data from ELS showed that 1.127 million students (36.38% of the U.S. class of 2004) graduated high school having earned at least one course credit in music. Fixed-effects regression procedures were used to compare standardized test scores of these music students to their non-music peers while controlling for variables from the domains of demography, prior academic achievement, time use, and attitudes toward school. Results indicated that music students did not outperform non-music students on the SAT once these systematic differences had been statistically controlled. The obtained pattern of results remained consistent and robust through internal replications with another standardized math test and when disaggregating music students by type of music studied.

“Magnesium Self-Experiments”, Branwen 2013

Magnesium: “Magnesium Self-Experiments”⁠, Gwern Branwen (2013-05-13; ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

3 magnesium self-experiments on magnesium l-threonate and magnesium citrate.

Encouraged by TruBrain’s magnesium & my magnesium l-threonate use, I design and run a blind random self-experiment to see whether magnesium citrate supplementation would improve my mood or productivity. I collected ~200 days of data at two dose levels. The analysis finds that the net effect was negative, but a more detailed look shows time-varying effects with a large initial benefit negated by an increasingly-negative effect. Combined with my expectations, the long half-life, and the higher-than-intended dosage, I infer that I overdosed on the magnesium. To verify this, I will be running a followup experiment with a much smaller dose.

“Working Memory Training Improvements and Gains in Non-trained Cognitive Tasks in Young and Older Adults”, Heinzel et al 2013

2013-heinzel.pdf: “Working memory training improvements and gains in non-trained cognitive tasks in young and older adults”⁠, Stephan Heinzel, Stefanie Schulte, Johanna Onken, Quynh-Lam Duong, Thomas G. Riemer, Andreas Heinz, Norbert Kathmann et al (2013-05-02; backlinks; similar):

Previous studies on working memory training have indicated that transfer to non-trained tasks of other cognitive domains may be possible.

The aim of this study is to compare working memory training and transfer effects between younger and older adults (n = 60). A novel approach to adaptive n-back training (12 sessions) was implemented by varying the working memory load and the presentation speed. All participants completed a neuropsychological battery of tests before and after the training.

On average, younger training participants achieved difficulty level 12 after training, while older training participants only reached difficulty level 5. In younger participants, transfer to Verbal Fluency and Digit Symbol Substitution test was found. In older participants, we observed a transfer to Digit Span Forward, CERAD Delayed Recall, and Digit Symbol Substitution test.

Results suggest that working memory training may be a beneficial intervention for maintaining and improving cognitive functioning in old age.

[Keywords: aging, working memory, training, transfer, processing speed, executive functions]

“Working Memory Training Is Associated With Lower Prefrontal Cortex Activation in a Divergent Thinking Task”, Vartanian et al 2013

2013-vartanian.pdf: “Working memory training is associated with lower prefrontal cortex activation in a divergent thinking task”⁠, O. Vartanian, M.-E. Jobidon, F. Bouak, A. Nakashima, I. Smith, Q. Lam, B. Cheung (2013-04-16; backlinks; similar):

  • We examined the effects of working memory (WM) training on divergent thinking.
  • WM training led to improvements in WM capacity and fluid intelligence.
  • WM training did not improve divergent thinking performance.
  • WM training was correlated with lower prefrontal activation.
  • Gain in fluid intelligence mediated the effect of training on activation in the prefrontal cortex.

Working memory (WM) training has been shown to lead to improvements in WM capacity and fluid intelligence. Given that divergent thinking loads on WM and fluid intelligence, we tested the hypothesis that WM training would improve performance and moderate neural function in the Alternate Uses Task (AUT)—a classic test of divergent thinking.

We tested this hypothesis by administering the AUT in the functional magnetic resonance imaging scanner following a short regimen of WM training (experimental condition), or engagement in a choice reaction time task not expected to engage WM (active control condition). Participants in the experimental group exhibited statistically-significant improvement in performance in the WM task as a function of training, as well as a statistically-significant gain in fluid intelligence. Although the 2 groups did not differ in their performance on the AUT, activation was statistically-significantly lower in the experimental group in ventrolateral prefrontal and dorsolateral prefrontal cortices—two brain regions known to play dissociable and critical roles in divergent thinking. Furthermore, gain in fluid intelligence mediated the effect of training on brain activation in ventrolateral prefrontal cortex.

These results indicate that a short regimen of WM training is associated with lower prefrontal activation—a marker of neural efficiency—in divergent thinking.

“Is Working Memory Training Effective? A Meta-Analytic Review”, Melby-Lervåg & Hulme 2013

“Is Working Memory Training Effective? A Meta-Analytic Review”⁠, Monica Melby-Lervåg, Charles Hulme (2013-02; ; backlinks; similar):

It has been suggested that working memory training programs are effective both as treatments for attention-deficit/​hyperactivity disorder (ADHD) and other cognitive disorders in children and as a tool to improve cognitive ability and scholastic attainment in typically developing children and adults. However, effects across studies appear to be variable, and a systematic meta-analytic review was undertaken. To be included in the review, studies had to be randomized controlled trials or quasi-experiments without randomization, have a treatment, and have either a treated group or an untreated control group.

23 studies with 30 group comparisons met the criteria for inclusion. The studies included involved clinical samples and samples of typically developing children and adults. Meta-analyses indicated that the programs produced reliable short-term improvements in working memory skills. For verbal working memory, these near-transfer effects were not sustained at follow-up, whereas for visuospatial working memory, limited evidence suggested that such effects might be maintained. More importantly, there was no convincing evidence of the generalization of working memory training to other skills (nonverbal and verbal ability, inhibitory processes in attention, word decoding, and arithmetic).

The authors conclude that memory training programs appear to produce short-term, specific training effects that do not generalize. Possible limitations of the review (including age differences in the samples and the variety of different clinical conditions included) are noted. However, current findings cast doubt on both the clinical relevance of working memory training programs and their utility as methods of enhancing cognitive functioning in typically developing children and healthy adults.

[Keywords: working memory training, ADHD, attention, learning disabilities]

“Training Working Memory: Limits of Transfer”, Sprenger et al 2013

2013-sprenger.pdf: “Training working memory: Limits of transfer”⁠, Amber M. Sprenger, Sharona M. Atkins, Donald J. Bolger, J. Isaiah Harbison, Jared M. Novick, Jeffrey S. Chrabaszcz et al (2013-01-01; backlinks)

“Exploring the Effectiveness of Commercial and Custom-built Games for Cognitive Training”, Smith et al 2013

2013-smith.pdf: “Exploring the effectiveness of commercial and custom-built games for cognitive training”⁠, Shamus P. Smith, Marina Stibric, David Smithson (2013-01-01; backlinks)

“Do Programs Designed to Train Working Memory, Other Executive Functions, and Attention Benefit Children With ADHD? A Meta-analytic Review of Cognitive, Academic, and Behavioral Outcomes”, Rapport et al 2013

2013-rapport.pdf: “Do programs designed to train working memory, other executive functions, and attention benefit children with ADHD? A meta-analytic review of cognitive, academic, and behavioral outcomes”⁠, Mark D. Rapport, Sarah A. Orban, Michael J. Kofler, Lauren M. Friedman (2013-01-01; backlinks)

“Increased Parietal Activity After Training of Interference Control”, Oelhafen et al 2013

2013-oelhafen.pdf: “Increased parietal activity after training of interference control”⁠, Stephan Oelhafen, Aki Nikolaidis, Tullia Padovani, Daniela Blaser, Thomas Koenig, Walter J. Perrig (2013-01-01; backlinks)

“Adaptive n-back Training Does Not Improve Fluid Intelligence at the Construct Level: Gains on Individual Tests Suggest That Training May Enhance Visuospatial Processing”, Colom et al 2013

2013-colom.pdf: “Adaptive <em>n< / em>-back training does not improve fluid intelligence at the construct level: Gains on individual tests suggest that training may enhance visuospatial processing”⁠, Roberto Colom, Francisco J. Román, Francisco J. Abad, Pei Chun Shih, Jesús Privado, Manuel Froufe, Sergio Escorial et al (2013-01-01; backlinks)

“Fractionating Human Intelligence”, Hampshire et al 2012

“Fractionating Human Intelligence”⁠, Adam Hampshire, Roger R. Highfield, Beth L. Parkin, Adrian M. Owen (2012-12-20; ; backlinks; similar):


  • We propose that human intelligence is composed of multiple independent components
  • Each behavioral component is associated with a distinct functional brain network
  • The higher-order g factor is an artifact of tasks recruiting multiple networks
  • The components of intelligence dissociate when correlated with demographic variables

What makes one person more intellectually able than another? Can the entire distribution of human intelligence be accounted for by just one general factor? Is intelligence supported by a single neural system? Here, we provide a perspective on human intelligence that takes into account how general abilities or “factors” reflect the functional organization of the brain. By comparing factor models of individual differences in performance with factor models of brain functional organization, we demonstrate that different components of intelligence have their analogs in distinct brain networks. Using simulations based on neuroimaging data, we show that the higher-order factor g is accounted for by cognitive tasks co-recruiting multiple networks. Finally, we confirm the independence of these components of intelligence by dissociating them using questionnaire variables. We propose that intelligence is an emergent property of anatomically distinct cognitive systems, each of which has its own capacity.

“A Potential Spatial Working Memory Training Task to Improve Both Episodic Memory and Fluid Intelligence”, Rudebeck et al 2012

“A Potential Spatial Working Memory Training Task to Improve Both Episodic Memory and Fluid Intelligence”⁠, Sarah R. Rudebeck, Daniel Bor, Angharad Ormond, Jill X. O’Reilly, Andy C. H. Lee (2012-10-23; backlinks; similar):

One current challenge in cognitive training is to create a training regime that benefits multiple cognitive domains, including episodic memory, without relying on a large battery of tasks, which can be time-consuming and difficult to learn. By giving careful consideration to the neural correlates underlying episodic and working memory, we devised a computerized working memory training task in which neurologically healthy participants were required to monitor and detect repetitions in two streams of spatial information (spatial location and scene identity) presented simultaneously (ie. a dual n-back paradigm).

Participants’ episodic memory abilities were assessed before and after training using two object and scene recognition memory tasks incorporating memory confidence judgments. Furthermore, to determine the generalizability of the effects of training, we also assessed fluid intelligence using a matrix reasoning task.

By examining the difference between pre-training and post-training performance (ie. gain scores), we found that the trainers, compared to non-trainers, exhibited a statistically-significant improvement in fluid intelligence after 20 days. Interestingly, pre-training fluid intelligence performance, but not training task improvement, was a statistically-significant predictor of post-training fluid intelligence improvement, with lower pre-training fluid intelligence associated with greater post-training gain. Crucially, trainers who improved the most on the training task also showed an improvement in recognition memory as captured by d-prime scores and estimates of recollection and familiarity memory. Training task improvement was a statistically-significant predictor of gains in recognition and familiarity memory performance, with greater training improvement leading to more marked gains. In contrast, lower pre-training recollection memory scores, and not training task improvement, led to greater recollection memory performance after training.

Our findings demonstrate that practice on a single working memory task can potentially improve aspects of both episodic memory and fluid intelligence, and that an extensive training regime with multiple tasks may not be necessary.

“Programmer Information Needs After Memory Failure”, Parnin & Rugaber 2012

“Programmer information needs after memory failure”⁠, Chris Parnin, Spencer Rugaber (2012-06-11; backlinks; similar):

Despite its vast capacity and associative powers, the human brain does not deal well with interruptions. Particularly in situations where information density is high, such as during a programming task, recovering from an interruption requires extensive time and effort. Although modern program development environments have begun to recognize this problem, none of these tools take into account the brain’s structure and limitations.

In this paper, we present a conceptual framework for understanding the strengths and weaknesses of human memory, particularly with respect to it ability to deal with work interruptions. The framework explains empirical results obtained from experiments in which programmers were interrupted while working.

Based on the framework, we discuss programmer information needs that development tools must satisfy and suggest several memory aids such tools could provide. We also describe our prototype implementation of these memory aids.

“Dual N-Back Meta-Analysis”, Branwen 2012

DNB-meta-analysis: “Dual n-Back Meta-Analysis”⁠, Gwern Branwen (2012-05-20; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Does DNB increase IQ? What factors affect the studies? Probably not: gains are driven by studies with weakest methodology like apathetic control groups.

I meta-analyze the >19 studies up to 2016 which measure IQ after an n-back intervention, finding (over all studies) a net gain (medium-sized) on the post-training IQ tests.

The size of this increase on IQ test score correlates highly with the methodological concern of whether a study used active or passive control groups⁠. This indicates that the medium effect size is due to methodological problems and that n-back training does not increase subjects’ underlying fluid intelligence but the gains are due to the motivational effect of passive control groups (who did not train on anything) not trying as hard as the n-back-trained experimental groups on the post-tests. The remaining studies using active control groups find a small positive effect (but this may be due to matrix-test-specific training, undetected publication bias, smaller motivational effects, etc.)

I also investigate several other n-back claims, criticisms, and indicators of bias, finding:

“Iodine and Adult IQ Meta-analysis”, Branwen 2012

Iodine: “Iodine and Adult IQ meta-analysis”⁠, Gwern Branwen (2012-02-29; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Iodine improves IQ in fetuses; adults as well? A meta-analysis of relevant studies says no.

Iodization is one of the great success stories of public health intervention: iodizing salt costs pennies per ton, but as demonstrated in randomized & natural experiments, prevents goiters, cretinism, and can boost population IQs by a fraction of a standard deviation in the most iodine-deficient populations.

These experiments are typically done on pregnant women, and results suggest that the benefits of iodization diminish throughout the trimesters of a pregnancy. So does iodization benefit normal healthy adults, potentially even ones in relatively iodine-sufficient Western countries?

Compiling existing post-natal iodization studies which use cognitive tests, I find that—outliers aside—the benefit appears to be nearly zero, and so likely it does not help normal healthy adults, particularly in Western adults.

“Intelligence: New Findings and Theoretical Developments”, Nisbett et al 2012

“Intelligence: New Findings and Theoretical Developments”⁠, Richard E. Nisbett, Joshua Aronson, Clancy Blair, William Dickens, James Flynn, Diane F. Halpern, Eric Turkheimer et al (2012-01-02; ; backlinks; similar):

We review new findings and new theoretical developments in the field of intelligence. New findings include the following: (a) Heritability of IQ varies statistically-significantly by social class. (b) Almost no genetic polymorphisms have been discovered that are consistently associated with variation in IQ in the normal range. (c) Much has been learned about the biological underpinnings of intelligence. (d) “Crystallized” and “fluid” IQ are quite different aspects of intelligence at both the behavioral and biological levels. (e) The importance of the environment for IQ is established by the 12-point to 18-point increase in IQ when children are adopted from working-class to middle-class homes. (f) Even when improvements in IQ produced by the most effective early childhood interventions fail to persist, there can be very marked effects on academic achievement and life outcomes. (g) In most developed countries studied, gains on IQ tests have continued, and they are beginning in the developing world. (h) Sex differences in aspects of intelligence are due partly to identifiable biological factors and partly to socialization factors. (1) The IQ gap between Blacks and Whites has been reduced by 0.33 SD in recent years. We report theorizing concerning (a) the relationship between working memory and intelligence, (b) the apparent contradiction between strong heritability effects on IQ and strong secular effects on IQ, (c) whether a general intelligence factor could arise from initially largely independent cognitive skills, (d) the relation between self-regulation and cognitive skills, and (e) the effects of stress on intelligence.

“Effects of Working Memory Training on Functional Connectivity and Cerebral Blood Flow during Rest”, Takeuchi et al 2012

2012-takeuchi.pdf: “Effects of working memory training on functional connectivity and cerebral blood flow during rest”⁠, Hikaru Takeuchi, Yasuyuki Taki, Rui Nouchi, Hiroshi Hashizume, Atsushi Sekiguchi, Yuka Kotozaki, Seishu Nakagawa et al (2012-01-01; backlinks)

“Influence of Neuroticism and Conscientiousness on Working Memory Training Outcome”, Studer-Luethi et al 2012

2012-studerluethi.pdf: “Influence of neuroticism and conscientiousness on working memory training outcome”⁠, Barbara Studer-Luethi, Susanne M. Jaeggi, Martin Buschkuehl, Walter J. Perrig (2012-01-01; backlinks)

“The Contribution of Working Memory to Fluid Reasoning: Capacity, Control, or Both?”, Chuderski & Necka 2012

2012-chuderski.pdf: “The contribution of working memory to fluid reasoning: Capacity, control, or both?”⁠, Adam Chuderski, Edward Necka (2012; ; backlinks; similar):

Fluid reasoning shares a large part of its variance with working memory capacity (WMC). The literature on working memory (WM) suggests that the capacity of the focus of attention responsible for simultaneous maintenance and integration of information within WM, as well as the effectiveness of executive control exerted over WM, determines individual variation in both WMC and reasoning.

In 6 experiments, we used a modified n-back task to test the amount of variance in reasoning that is accounted for by each of these 2 theoretical constructs. The capacity of the focus accounted for up to 62% of variance in fluid reasoning, while the recognition of stimuli encoded outside of the focus was not related to reasoning ability. Executive control, measured as the ability to reject distractors identical to targets but presented in improper contexts, accounted for up to 13% of reasoning variance.

Multiple analyses indicated that capacity and control predicted non-overlapping amounts of variance in reasoning.

[Keywords: working memory, attentional capacity, executive control, fluid reasoning, n-back task]

“Differential Effects of Reasoning and Speed Training in Children”, Mackey et al 2011

2011-mackey.pdf: “Differential effects of reasoning and speed training in children”⁠, Allyson P. Mackey, Susanna S. Hill, Susan I. Stone, Silvia A. Bunge (2011-11-23; backlinks; similar):

The goal of this study was to determine whether intensive training can ameliorate cognitive skills in children.

Children aged 7 to 9 from low socioeconomic backgrounds participated in one of 2 cognitive training programs for 60 minutes/​day and 2 days/​week, for a total of 8 weeks. Both training programs consisted of commercially available computerized and non-computerized games. Reasoning training emphasized planning and relational integration; speed training emphasized rapid visual detection and rapid motor responses. Standard assessments of reasoning ability—the Test of Non-Verbal Intelligence (TONI-3) and cognitive speed (Coding B from WISC IV)—were administered to all children before and after training. Neither group was exposed to these standardized tests during training.

Children in the reasoning group improved substantially on TONI (Cohen’s d = 1.51), exhibiting an average increase of 10 points in Performance IQ, but did not improve on Coding. By contrast, children in the speed group improved substantially on Coding (d = 1.15), but did not improve on TONI.

Counter to widespread belief, these results indicate that both fluid reasoning and processing speed are modifiable by training.

“The Effect of Cognitive Training on Recall Range and Speed of Information Processing in the Working Memory of Dyslexic and Skilled Readers”, Shiran & Breznitz 2011

2011-shiran.pdf: “The effect of cognitive training on recall range and speed of information processing in the working memory of dyslexic and skilled readers”⁠, Amir Shiran, Zvia Breznitz (2011-01-01; backlinks)

“The Efficacy and Psychophysiological Correlates of Dual-attention Tasks in Eye Movement Desensitization and Reprocessing (EMDR)”, Schubert et al 2011

2011-schubert.pdf: “The efficacy and psychophysiological correlates of dual-attention tasks in eye movement desensitization and reprocessing (EMDR)”⁠, Sarah J. Schubert, Christopher W. Lee, Peter D. Drummond (2011-01-01; backlinks)

“The Title of the Poster”

2011-jaeggi-poster.pdf: “The Title of the Poster” (2011-01-01; backlinks)

“Improving Working Memory: the Effect of Combining Cognitive Activity and Anodal Transcranial Direct Current Stimulation to the Left Dorsolateral Prefrontal Cortex”, Andrews et al 2011

2011-andrews.pdf: “Improving working memory: the effect of combining cognitive activity and anodal transcranial direct current stimulation to the left dorsolateral prefrontal cortex”⁠, Sophie C. Andrews, Kate E. Hoy, Peter G. Enticott, Zafiris J. Daskalakis, Paul B. Fitzgerald (2011-01-01; backlinks)

“Remember the Future: Working Memory Training Decreases Delay Discounting among Stimulant Addicts”, Bickel et al 2011

“Remember the future: working memory training decreases delay discounting among stimulant addicts”⁠, Bickel, Warren K. Yi, Richard Landes, Reid D. Hill, Paul F. Baxter, Carole (2011; backlinks; similar):

Excessive discounting of future rewards has been observed in a variety of disorders and has been linked both to valuation of the past and to memory of past events. To explore the functionality of discounting and memory, we examined whether training of working memory would result in less discounting of future rewards.

In this study, 27 adults in treatment for stimulant use were randomly assigned to receive either working memory training or control training according to a yoked experimental design. Measures of delay discounting and several other cognitive behaviors were assessed pre-training and posttraining. Rates of discounting of delayed rewards were statistically-significantly reduced among those who received memory training but were unchanged among those who received control training; other cognitive assessments were not affected by memory training. Discount rates were positively correlated with memory training performance measures.

To our knowledge, this is the first study demonstrating that neurocognitive training on working memory decreases delay discounting. These results offer further evidence of a functional relationship between delay discounting and working memory.

“Does Working Memory Training Work? The Promise and Challenges of Enhancing Cognition by Training Working Memory”, Morrison & Chein 2010

2011-morrison.pdf: “Does working memory training work? The promise and challenges of enhancing cognition by training working memory”⁠, Alexandra B. Morrison, Jason M. Chein (2010-11-17; backlinks; similar):

A growing body of literature shows that one’s working memory (WM) capacity can be expanded through targeted training. Given the established relationship between WM and higher cognition, these successful training studies have led to speculation that WM training may yield broad cognitive benefits. This review considers the current state of the emerging WM training literature, and details both its successes and limitations.

We identify 2 distinct approaches to WM training, ‘strategy training’ and ‘core training’, and highlight both the theoretical and practical motivations that guide each approach. Training-related increases in WM capacity have been successfully demonstrated across a wide range of subject populations, but different training techniques seem to produce differential impacts upon the broader landscape of cognitive abilities. In particular, core WM training studies seem to produce more far-reaching transfer effects, likely because they target domain-general mechanisms of WM. The results of individual studies encourage optimism regarding the value of WM training as a tool for general cognitive enhancement.

However, we discuss several limitations that should be addressed before the field endorses the value of this approach.

[Keywords: cognitive training, transfer, cognitive control, fluid intelligence]

“The Replication Crisis: Flaws in Mainstream Science”, Branwen 2010

Replication: “The Replication Crisis: Flaws in Mainstream Science”⁠, Gwern Branwen (2010-10-27; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

2013 discussion of how systemic biases in science, particularly medicine and psychology, have resulted in a research literature filled with false positives and exaggerated effects, called ‘the Replication Crisis’.

Long-standing problems in standard scientific methodology have exploded as the “Replication Crisis”: the discovery that many results in fields as diverse as psychology, economics, medicine, biology, and sociology are in fact false or quantitatively highly inaccurately measured. I cover here a handful of the issues and publications on this large, important, and rapidly developing topic up to about 2013, at which point the Replication Crisis became too large a topic to cover more than cursorily. (A compilation of some additional links are provided for post-2013 developments.)

The crisis is caused by methods & publishing procedures which interpret random noise as important results, far too small datasets, selective analysis by an analyst trying to reach expected/​desired results, publication bias, poor implementation of existing best-practices, nontrivial levels of research fraud, software errors, philosophical beliefs among researchers that false positives are acceptable, neglect of known confounding like genetics, and skewed incentives (financial & professional) to publish ‘hot’ results.

Thus, any individual piece of research typically establishes little. Scientific validation comes not from small p-values, but from discovering a regular feature of the world which disinterested third parties can discover with straightforward research done independently on new data with new procedures—replication.

“The Concurrent Validity of the N-back Task As a Working Memory Measure”, Jaeggi et al 2010b

2010-jaeggi-2.pdf: “The concurrent validity of the N-back task as a working memory measure”⁠, Susanne M. Jaeggi, Martin Buschkuehl, Walter J. Perrig, Beat Meier (2010-04-19; ; backlinks):

The n-back task is used extensively in literature as a working-memory (WM) paradigm and it is increasingly used as a measure of individual differences. However, not much is known about the psychometric properties of this task and the current study aims to shed more light on this issue.

We first review the current literature on the psychometric properties of the n-back task.

With 3 experiments using task variants with different stimuli and load levels, we then investigate the nature of the n-back task by investigating its relationship to WM, and its role as an inter-individual difference measure.

Consistent with previous literature, our data suggest that the n-back task is not a useful measure of individual differences in WM, partly because of its insufficient reliability. Nevertheless, the task seems to be useful for experimental research in WM and also well predicts inter-individual differences in other higher cognitive functions, such as fluid intelligence⁠, especially when used at higher levels of load.

[Keywords: validity, reliability, inter-individual differences, intelligence, executive functions]

“Nootropics”, Branwen 2010

Nootropics: “Nootropics”⁠, Gwern Branwen (2010-01-02; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar)

“Mindfulness Meditation Improves Cognition: Evidence of Brief Mental Training”, Zeidan et al 2010

2010-zeidan.pdf: “Mindfulness meditation improves cognition: Evidence of brief mental training”⁠, Fadel Zeidan, Susan K. Johnson, Bruce J. Diamond, Zhanna David, Paula Goolkasian (2010-01-01; backlinks)

“M-CASTL Synthesis Report”, SBA 2010

2010-seidler.pdf: “M-CASTL Synthesis Report”⁠, SBA (2010-01-01; backlinks)

“WM and Spontaneous ER_resubmission”, Weaver 2010

2010-schmeichel.pdf: “WM and Spontaneous ER_resubmission”⁠, Joseph Weaver (2010-01-01; backlinks)

“Beyond Genetics in Mental Rotation Test Performance”, Moè & Pazzaglia 2010

2010-moe.pdf: “Beyond genetics in Mental Rotation Test performance”⁠, Angelica Moè, Francesca Pazzaglia (2010-01-01; backlinks)

“The Relationship between n-back Performance and Matrix Reasoning — Implications for Training and Transfer”, Jaeggi et al 2010

2010-jaeggi.pdf: “The relationship between <em>n< / em>-back performance and matrix reasoning — implications for training and transfer”⁠, Susanne M. Jaeggi, Barbara Studer-Luethi, Martin Buschkuehl, Yi-Fen Su, John Jonides, Walter J. Perrig et al (2010-01-01; backlinks)

“Investigating the Predictive Roles of Working Memory and IQ in Academic Attainment”, Alloway & Alloway 2010

2010-alloway.pdf: “Investigating the predictive roles of working memory and IQ in academic attainment”⁠, Tracy Packiam Alloway, Ross G. Alloway (2010-01-01; backlinks)

“Influence of Age on Practice Effects in Longitudinal Neurocognitive Change”, Salthouse 2010

“Influence of Age on Practice Effects in Longitudinal Neurocognitive Change”⁠, Timothy A. Salthouse (2010; ; backlinks; similar):

Longitudinal comparisons of neurocognitive functioning often reveal stability or age-related increases in performance among adults under about 60 years of age. Because nearly monotonic declines with increasing age are typically evident in cross-sectional comparisons, there is a discrepancy in the inferred age trends based on the two types of comparisons. The current research investigated the role of practice effects in longitudinal comparisons on the discrepancy.

Method: Longitudinal data over an average interval of 2.5 years were available on five abilities (ie. reasoning, spatial visualization, episodic memory, perceptual speed, vocabulary) in a sample of 1,616 adults ranging from 18 to over 80 years of age. Practice effects were estimated from comparisons of the performance of people of the same age tested for either the first or second time, after adjusting for the possibility of selective attrition.

Results: Increased age was associated with statistically-significantly more negative longitudinal changes with each ability. All of the estimated practice effects were positive, but they varied in magnitude across neurocognitive abilities and as a function of age. After adjusting for practice effects the longitudinal changes were less positive at younger ages and slightly less negative at older ages.

Conclusions: It was concluded that some, but not all, of the discrepancy between cross-sectional and longitudinal age trends in neurocognitive functioning is attributable to practice effects positively biasing the longitudinal trends. These results suggest that the neurobiological substrates of neurocognitive functioning may change across different periods in adulthood.

“Adolescent Sleep and Fluid Intelligence Performance”, Johnston et al 2010

“Adolescent sleep and fluid intelligence performance”⁠, Anna Johnston, Michael Gradisar, Hayley Dohnt, Michael Billows, Stephanie McCappin (2010; ; backlinks; similar):

Fluid intelligence involves novel problem-solving and may be susceptible to poor sleep. This study examined relationships between adolescent sleep, fluid intelligence, and academic achievement. Participants were 217 adolescents (42% male) aged 13 to 18 years (mean age, 14.9 years; SD = 1.0) in grades 9–11. Fluid intelligence was predicted to mediate the relationship between adolescent sleep and academic achievement. Students completed online questionnaires of self-reported sleep, fluid intelligence (Letter Sets and Number Series), and self-reported grades. Total sleep time was not statistically-significantly related to fluid intelligence nor academic achievement (both p > 0.05); however, sleep difficulty (eg. difficulty initiating sleep, unrefreshing sleep) was related to both (p < 0.05). The strength of the relationship between sleep difficulty and grades was reduced when fluid intelligence was introduced into the model; however, the z-score was not statistically-significant to confirm mediation.Nevertheless, fluid intelligence is a cognitive ability integral in academic achievement, and in this study has been shown it to be susceptible to sleep impairments (but not duration) in adolescents.

“Differential Dorsolateral Prefrontal Cortex Activation during a Verbal n-back Task according to Sensory Modality”, Rodriguez-Jimenez et al 2009

2009-rodriguezjimenez.pdf: “Differential dorsolateral prefrontal cortex activation during a verbal n-back task according to sensory modality”⁠, Roberto Rodriguez-Jimenez, Cesar Avila, Cristina Garcia-Navarro, Alexandra Bagney, Ana Martinez de Aragon et al (2009-12-14; backlinks; similar):

Functional neuroimaging studies carried out on healthy volunteers while performing different n-back tasks have shown a common pattern of bilateral frontoparietal activation, especially of the dorsolateral prefrontal cortex (DLPFC). Our objective was to use functional magnetic resonance imaging (fMRI) to compare the pattern of brain activation while performing two similar n-back tasks which differed in their presentation modality. Thirteen healthy volunteers completed a verbal 2-back task presenting auditory stimuli, and a similar 2-back task presenting visual stimuli. A conjunction analysis showed bilateral activation of frontoparietal areas including the DLPFC. The left DLPFC and the superior temporal gyrus showed a greater activation in the auditory than in the visual condition, whereas posterior brain regions and the anterior cingulate showed a greater activation during the visual than during the auditory task. Thus, brain areas involved in the visual and auditory versions of the n-back task showed an important overlap between them, reflecting the supramodal characteristics of working memory. However, the differences found between the two modalities should be considered in order to select the most appropriate task for future clinical studies.

[Keywords: fMRI⁠, Working memory, n-back task, Auditory, Visual, DLPFC]

“How Useful Is Executive Control Training? Age Differences in near and Far Transfer of Task-switching Training”, Karbach & Kray 2009

2009-karbach.pdf: “How useful is executive control training? Age differences in near and far transfer of task-switching training”⁠, Julia Karbach, Jutta Kray (2009-10-14; backlinks; similar):

Although executive functions can be improved by training, little is known about the extent to which these training-related benefits can be transferred to other tasks, or whether this transfer can be modulated by the type of training.

This study investigated lifespan changes in near transfer of task-switching training to structurally similar tasks and its modulation by verbal self-instructions and variable training, as well as far transfer to structurally dissimilar ‘executive’ tasks and fluid intelligence.

3 age groups (8–10; 18–26; 62–76 years of age) were examined in a pretest-training-posttest design.

We found near transfer of task-switching training in all age groups, especially in children and older adults. Near transfer was enhanced in adults and impaired in children when training tasks were variable. We also found substantial far transfer to other executive tasks and fluid intelligence in all age groups, pointing to the transfer of relatively general executive control abilities after training.

“Generalizing From One Example”, Alexander 2009

“Generalizing From One Example”⁠, Scott Alexander (2009-04-28; ⁠, ⁠, ⁠, ; backlinks; similar):

[Alexander defines the “typical mind fallacy”: everyone reasons about their mental experiences as if they are universal. People with vivid visual imagery assume everyone can see things in “the mind’s eye” while ‘aphantasics’ assume that this is simply a poetic metaphor; people with color-blindness wonder why other people get so worked up about various shades of gray, and people with anosmia are puzzled by the focus on flowers etc. Further examples include maladaptive daydreaming, pain insensitivity, the prevalence of visual & auditory hallucinations in mentally-healthy individuals like ‘scintillating scotoma’, misophonia⁠, hearing voices⁠, inner monologues, facial self-awareness, trypophobia⁠, Severely Deficient Autobiographical Memory⁠, hypermnesia, ASMR⁠, face blindness/​prosopagnosia⁠, musical anhedonia⁠, ‘the call of the void’/​intrusive thoughts⁠, hypnagogia⁠, the nasal dilation cycle

This phenomenon for visual imagery was discovered only recently by Francis Galton⁠, who asked if the interminable debate between philosophers/​psychologists like Berkeley or Behaviorists like Skinner, where neither could accept that there was (or was not) visual imagery, was because both were right—some people have extremely vivid mental imagery, while others have none at all. He simply circulated a survey and asked. Turned out, most people do but some don’t.

The typical mind fallacy may explain many interpersonal conflicts and differences in advice: we underappreciate the sheer cognitive diversity of mankind, because we only have access to our limited personal anecdote, and people typically do not discuss all their differences because they don’t realize they exist nor have a vocabulary/​name.]

“Dual N-Back FAQ”, Branwen 2009

DNB-FAQ: “Dual n-Back FAQ”⁠, Gwern Branwen (2009-03-25; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

A compendium of DNB, WM, IQ information up to 2015.

Between 2008 and 2011, I collected a number of anecdotal reports about the effects of n-backing; there are many other anecdotes out there, but the following are a good representation—for what they’re worth.

“Spaced Repetition for Efficient Learning”, Branwen 2009

Spaced-repetition: “Spaced Repetition for Efficient Learning”⁠, Gwern Branwen (2009-03-11; ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Efficient memorization using the spacing effect: literature review of widespread applicability, tips on use & what it’s good for.

Spaced repetition is a centuries-old psychological technique for efficient memorization & practice of skills where instead of attempting to memorize by ‘cramming’, memorization can be done far more efficiently by instead spacing out each review, with increasing durations as one learns the item, with the scheduling done by software. Because of the greater efficiency of its slow but steady approach, spaced repetition can scale to memorizing hundreds of thousands of items (while crammed items are almost immediately forgotten) and is especially useful for foreign languages & medical studies.

I review what this technique is useful for, some of the large research literature on it and the testing effect (up to ~2013, primarily), the available software tools and use patterns, and miscellaneous ideas & observations on it.

“Zinc Status and Cognitive Function of Pregnant Women in Southern Ethiopia”, Stoecker et al 2009

2009-stoecker.pdf: “Zinc status and cognitive function of pregnant women in Southern Ethiopia”⁠, B J. Stoecker, Y. Abebe, L. Hubbs-Tait, T. S Kennedy, R. S Gibson, I. Arbide, A. Teshome, J. Westcott et al (2009-01-01; backlinks)

“Study on Improving Fluid Intelligence through Cognitive Training System Based on Gabor Stimulus”, Qiu et al 2009

2009-qiu.pdf: “Study on Improving Fluid Intelligence through Cognitive Training System Based on Gabor Stimulus”⁠, Feiyue Qiu, Qinqin Wei, Liying Zhao, Lifang Lin (2009-01-01; backlinks)

“Reduced Misinformation Effects following Saccadic Bilateral Eye Movements”, Parker et al 2009

2009-parker.pdf: “Reduced misinformation effects following saccadic bilateral eye movements”⁠, Andrew Parker, Sharon Buckley, Neil Dagnall (2009-01-01; backlinks)

“Horizontal Saccadic Eye Movements Enhance the Retrieval of Landmark Shape and Location Information”, Brunyé et al 2009

2009-brunye.pdf: “Horizontal saccadic eye movements enhance the retrieval of landmark shape and location information”⁠, Tad T. Brunyé, Caroline R. Mahoney, Jason S. Augustyn, Holly A. Taylor (2009-01-01; backlinks)

“Conducting the Train of Thought: Working Memory Capacity, Goal Neglect, and Mind Wandering in an Executive-control Task”, McVay & Kane 2009

“Conducting the train of thought: working memory capacity, goal neglect, and mind wandering in an executive-control task”⁠, Jennifer C. McVay, Michael J. Kane (2009; backlinks; similar):

On the basis of the executive-attention theory of working memory capacity (WMC; eg. M. J. Kane, A. R. A. Conway, D. Z. Hambrick, & R. W. Engle, 2007), the authors tested the relations among WMC, mind wandering, and goal neglect in a sustained attention to response task (SART; a go/​no-go task). In 3 SART versions, making conceptual versus perceptual processing demands, subjects periodically indicated their thought content when probed following rare no-go targets. SART processing demands did not affect mind-wandering rates, but mind-wandering rates varied with WMC and predicted goal-neglect errors in the task; furthermore, mind-wandering rates partially mediated the WMC-SART relation, indicating that WMC-related differences in goal neglect were due, in part, to variation in the control of conscious thought.

“The Age of Reason: Financial Decisions over the Life Cycle and Implications for Regulation”, Agarwal et al 2009

2009-agarwal.pdf: “The Age of Reason: Financial Decisions over the Life Cycle and Implications for Regulation”⁠, Sumit Agarwal, John C. Driscoll, Xavier Gabaix, David Laibson (2009; ; backlinks; similar):

Many consumers make poor financial choices, and older adults are particularly vulnerable to such errors. About half of the population between ages 80 and 89 have a medical diagnosis of substantial cognitive impairment. We study life-cycle patterns in financial mistakes using a proprietary database with information on 10 types of credit transactions. Financial mistakes include suboptimal use of credit card balance transfer offers and excess interest rate and fee payments. In a cross section of prime borrowers, middle-aged adults made fewer financial mistakes than either younger or older adults. We conclude that financial mistakes follow a U-shaped pattern, with the cost-minimizing performance occurring around age 53. We analyze nine regulatory strategies that may help individuals avoid financial mistakes. We discuss laissez-faire, disclosure, nudges, financial “driver’s licenses”, advance directives, fiduciaries, asset safe harbors, and ex post and ex ante regulatory oversight. Finally, we pose seven questions for future research on cognitive limitations and associated policy responses.

“Melatonin”, Branwen 2008

Melatonin: “Melatonin”⁠, Gwern Branwen (2008-12-19; ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Melatonin improves sleep, & sleep is valuable

I discuss melatonin’s effects on sleep & its safety with research up to 2015; I segue into the general benefits of sleep and the severely disrupted sleep of the modern Western world, the cost of melatonin use and the benefit (eg. enforcing regular bedtimes), followed by a basic cost-benefit analysis of melatonin concluding that the net profit is large enough to be worth giving it a try barring unusual conditions or very pessimistic safety estimates.

“Transfer of Learning After Updating Training Mediated by the Striatum”, Dahlin et al 2008

2008-dahlin.pdf: “Transfer of Learning After Updating Training Mediated by the Striatum”⁠, Erika Dahlin, Anna Stigsdotter Neely, Anne Larsson, Lars Bäckman, Lars Nyberg (2008-06-13; ; backlinks; similar):

Process-specific training can improve performance on untrained tasks, but the magnitude of gain is variable and often there is no transfer at all.

We demonstrate transfer to a 3-back test of working memory after 5 weeks of training in updating. The transfer effect was based on a joint training-related activity increase for the criterion (letter memory) and transfer tasks in a striatal region that also was recruited pretraining. No transfer was observed to a task that did not engage updating and striatal regions, and age-related striatal changes imposed constraints on transfer.

These findings indicate that transfer can occur if the criterion and transfer tasks engage specific overlapping processing components and brain regions.

“Common and Unique Components of Inhibition and Working Memory: An FMRI, Within-subjects Investigation”, McNab et al 2008

“Common and unique components of inhibition and working memory: An fMRI, within-subjects investigation”⁠, Fiona McNab, Gaelle Leroux, Fredrik Strand, Lisa Thorell, Sissela Bergman, Torkel Klingberg (2008-05-16; backlinks; similar):

Behavioural findings indicate that the core executive functions of inhibition and working memory are closely linked, and neuroimaging studies indicate overlap between their neural correlates. There has not, however, been a comprehensive study, including several inhibition tasks and several working memory tasks, performed by the same subjects. In the present study, 11 healthy adult subjects completed separate blocks of 3 inhibition tasks (a stop task, a go/​no-go task and a flanker task), and 2 working memory tasks (one spatial and one verbal). Activation common to all 5 tasks was identified in the right inferior frontal gyrus, and, at a lower threshold, also the right middle frontal gyrus and right parietal regions (BA 40 and BA 7). Left inferior frontal regions of interest (ROIs) showed a statistically-significant conjunction between all tasks except the flanker task. The present study could not pinpoint the specific function of each common region, but the parietal region identified here has previously been consistently related to working memory storage and the right inferior frontal gyrus has been associated with inhibition in both lesion and imaging studies. These results support the notion that inhibitory and working memory tasks involve common neural components, which may provide a neural basis for the interrelationship between the two systems.

“CAC08_Karbach”, dast003 2008

2008-karbach.pdf: “CAC08_Karbach”⁠, dast003 (2008-01-01; backlinks)

“Population Aging, Intracohort Aging, and Sociopolitical Attitudes”, Danigelis et al 2007

2007-danigelis.pdf: “Population Aging, Intracohort Aging, and Sociopolitical Attitudes”⁠, Nicholas L. Danigelis, Melissa Hardy, Stephen J. Cutler (2007-10-01; backlinks; similar):

Prevailing stereotypes of older people hold that their attitudes are inflexible or that aging tends to promote increasing conservatism in sociopolitical outlook. In spite of mounting scientific evidence demonstrating that learning, adaptation, and reassessment are behaviors in which older people can and do engage, the stereotype persists.

We use U.S. General Social Survey (GSS) data from 25 surveys between 1972 and 2004 to formally assess the magnitude and direction of changes in attitudes that occur within cohorts at different stages of the life course. We decompose changes in sociopolitical attitudes into the proportions attributable to cohort succession and intracohort aging for three categories of items: attitudes toward historically subordinate groups, civil liberties, and privacy.

We find that statistically-significant intracohort change in attitudes occurs in cohorts-in-later-stages (age 60 and older) as well as cohorts-in-earlier-stages (ages 18 to 39), that the change for cohorts-in-later-stages is frequently greater than that for cohorts-in-earlier-stages, and that the direction of change is most often toward increased tolerance rather than increased conservatism.

These findings are discussed within the context of population aging and development.

“The Predictive Relationship between Achievement and Participation in Music and Achievement in Core Grade 12 Academic Subjects”, Gouzouasis et al 2007

2007-gouzouasis.pdf: “The predictive relationship between achievement and participation in music and achievement in core Grade 12 academic subjects”⁠, Peter Gouzouasis, Martin Guhn, Nand Kishor (2007-01-31; ; backlinks; similar):

The relationship between musical training and general intellectual capacity as well as academic achievement has been discussed in numerous contexts.

In our study, we examined the relationship between participation and achievement in music and achievement in academic courses, based on data from 3 consecutive British Columbia student cohorts.

Across the 3 cohorts, we consistently found that music participation was associated with generally higher academic achievement, and that Grade 11 music course scores predicted Grade 12 academic achievement scores in linear regression analyses.

Our results support the notion that the time dedicated to music participation does not impede, but rather goes hand in hand with or even fosters academic excellence in other ‘core’ subjects.

[Super-confounded, of course, and randomized musical training does not do anything.]

“Effects of Three Years of Piano Instruction on Children’s Academic Achievement, School Performance and Self-Esteem”, Costa-Giomi 2004

2004-costagiomi.pdf: “Effects of Three Years of Piano Instruction on Children’s Academic Achievement, School Performance and Self-Esteem”⁠, Eugenia Costa-Giomi (2004-04-01; ; backlinks; similar):

This study of the effects of three years of piano instruction is based on a sample of 117 fourth-grade children attending public schools in Montreal. The children had never participated in formal music instruction, did not have a piano at home, and their annual family income was below $40,000 Can. Children in the experimental group (n = 63) received individual piano lessons weekly for three years and were given an acoustic piano at no cost to their families. Children in the control group (n = 54) did not participate in formal music instruction. Participants were administered tests of self-esteem, academic achievement, cognitive abilities, musical abilities, and motor proficiency at the beginning of the project and throughout the three years of piano instruction. The results indicated that piano instruction had a positive effect on children’s self-esteem and school music marks but did not affect their academic achievement in math and language as measured by standardized tests and school report cards.

“Inducing Inductive Reasoning: Does It Transfer to Fluid Intelligence?”, Klauer & J. 2002

2002-klauer.pdf: “Inducing Inductive Reasoning: Does It Transfer to Fluid Intelligence?”⁠, Klauer, K. J. (2002-01-01; backlinks)

“Peopleware: Why Measure Performance”, DeMarco & Lister 2001

2001-demarco-peopleware-whymeasureperformance.pdf: “Peopleware: Why Measure Performance”⁠, Tom DeMarco, Timothy Lister (2001-01-01; ; backlinks)

“It’s the Latency, Stupid”, Cheshire 2001

“It’s the Latency, Stupid”⁠, Stuart Cheshire (2001; ; backlinks; similar):

[Seminal essay explaining why the rollout of “broadband” home connections to replace 56k dialups had not improved regular WWW browsing as much as people expected: while broadband had greater throughput, it had similar (or worse) latency.

Because much of the wallclock time of any Internet connection is spent setting up and negotiating with the other end, and not that much is spent on the raw transfer of large numbers of bytes, the speedup is far smaller than one would expect by dividing the respective bandwidths.

Further, while bandwidth/​throughput is easy to improve by adding more or higher-quality connections and can be patched elsewhere in the system by adding parallelism or upgrading parts or investing in data compression, the latency-afflicted steps are stubbornly serial, any time lost is physically impossible to retrieve, and many steps are inherently limited by the speed of light—more capacious connections quickly run into Amdahl’s law⁠, where the difficult-to-improve serial latency-bound steps dominate the overall task. As Cheshire summarizes it:]

  1. Fact One: Making more bandwidth is easy.
  2. Fact Two: Once you have bad latency you’re stuck with it.
  3. Fact Three: Current consumer devices have appallingly bad latency.
  4. Fact Four: Making limited bandwidth go further is easy.

…That’s the problem with communications devices today. Manufacturers say “speed” when they mean “capacity”. The other problem is that as far as the end-user is concerned, the thing they want to do is transfer large files quicker. It may seem to make sense that a high-capacity slow link might be the best thing for the job. What the end-user doesn’t see is that in order to manage that file transfer, their computer is sending dozens of little control messages back and forth. The thing that makes computer communication different from television is interactivity, and interactivity depends on all those little back-and-forth messages.

The phrase “high-capacity slow link” that I used above probably looked very odd to you. Even to me it looks odd. We’ve been used to wrong thinking for so long that correct thinking looks odd now. How can a high-capacity link be a slow link? High-capacity means fast, right? It’s odd how that’s not true in other areas. If someone talks about a “high-capacity” oil tanker, do you immediately assume it’s a very fast ship? I doubt it. If someone talks about a “large-capacity” truck, do you immediately assume it’s faster than a small sports car?

We have to start making that distinction again in communications. When someone tells us that a modem has a speed of 28.8 kbit/​sec we have to remember that 28.8 kbit/​sec is its capacity, not its speed. Speed is a measure of distance divided by time, and ‘bits’ is not a measure of distance.

I don’t know how communications came to be this way. Everyone knows that when you buy a hard disk you should check what its seek time is. The maximum transfer rate is something you might also be concerned with, but the seek time is definitely more important. Why does no one think to ask what a modem’s ‘seek time’ is? The latency is exactly the same thing. It’s the minimum time between asking for a piece of data and getting it, just like the seek time of a disk, and it’s just as important.


2000-fishbain.pdf: “PME00042” (2000-01-01; ; backlinks)

“Drugs and Aging 15: 365-375, Nov 1999”, L et al 1999

1999-fratiglioni.pdf: “Drugs and Aging 15: 365-375, Nov 1999”⁠, Fratiglioni L, De Ronchi D, Ag;auuero-Torres H (1999-01-01; backlinks)

“Inductive Reasoning in Third Grade: Intervention Promises and Constraints”, Hamers et al 1998

1998-hamers.pdf: “Inductive Reasoning in Third Grade: Intervention Promises and Constraints”⁠, J. H. M. Hamers, E. de Koning, K. Sijtsma (1998-04; ; backlinks; similar):

The results of 2 evaluation studies with respect to a programme for enhancing inductive reasoning ability of third grade students are presented. The programme is a classroom version of the German programme Denktraining für Kinder 1 (“Cognitive training for children”; Klauer 1989).

In the first formative evaluation study, 2 experimental groups with 30 students in total and one control group with 9 students were involved. Observations during the lessons, and teachers’ reports showed that teachers were able to implement the programme. Both experimental groups statistically-significantly outperformed the control group on a posttest immediately after the programme and on a follow-up test 3 1⁄2 months later. Further analyses of the data revealed tentative evidence of the superiority of a direct teaching method.

In the second summative evaluation study, the same programme was applied to a larger sample (experimental groups: n = 99 in total; and control groups: n = 232 in total) of third grade students. On the basis of Study 1, the programme instructions were slightly changed. The experimental groups scored statistically-significantly higher on a posttest 3 months after completion of the programme.

“The Efficacy of Psychological, Educational, and Behavioral Treatment: Confirmation from Meta-Analysis”, Lipsey & Wilson 1993

1993-lipsey.pdf: “The Efficacy of Psychological, Educational, and Behavioral Treatment: Confirmation from Meta-Analysis”⁠, Mark W. Lipsey, David B. Wilson (1993-12-01; ⁠, ⁠, ⁠, ; backlinks; similar):

Conventional reviews of research on the efficacy of psychological, educational, and behavioral treatments often find considerable variation in outcome among studies and, as a consequence, fail to reach firm conclusions about the overall effectiveness of the interventions in question. In contrast, meta-analysis reviews show a strong, dramatic pattern of positive overall effects that cannot readily be explained as artifacts of meta-analytic technique or generalized placebo effects. Moreover, the effects are not so small that they can be dismissed as lacking practical or clinical-significance. Although meta-analysis has limitations, there are good reasons to believe that its results are more credible than those of conventional reviews and to conclude that well-developed psychological, educational, and behavioral treatment is generally efficacious.

“Chess Expertise and Memory for Chess Positions in Children and Adults”, Schneider et al 1993

1993-schneider.pdf: “Chess Expertise and Memory for Chess Positions in Children and Adults”⁠, Wolfgang Schneider, Hans Gruber, Andreas Gold, Klaus Opwis (1993-12-01; ; backlinks; similar):

This paper presents a replication and extension of Chi′s (1978) classic study on chess expertise [“Knowledge structures and memory development”]. A major outcome of Chi′s research was that although adult novices had a better memory span than child experts, the children showed better memory for chess positions than the adults.

The major goal of this study was to explore the effects of the following task characteristics on memory performance: (1) Familiarity with the constellation of chess pieces (ie. meaningful versus random positions) and (2) familiarity with both the geometrical structure of the board and the form and color of chess pieces.

The tasks presented to the four groups of subjects (ie. child experts and novices, adult experts and novices) included memory for meaningful and random chess positions as well as memory for the location of wooden pieces of different forms on a board geometrically structured by circles, triangles, rhombuses, etc. (control task 1). Further, a digit span memory task was given (control task 2). The major assumption was that the superiority of experts should be greatest for the meaningful chess positions, somewhat reduced but still statistically-significant for the random positions, and nonsignificant for the board control task.

Only age effects were expected for the digit span task. The results conformed to this pattern, showing that each type of knowledge contributed to the experts′ superior memory span for chess positions.

“How Much Can We Boost IQ and Scholastic Achievement?”, Jensen 1969

1969-jensen.pdf: “How Much Can We Boost IQ and Scholastic Achievement?”⁠, Arthur R. Jensen (1969-05-01; ⁠, ⁠, ; backlinks; similar):

Arthur Jensen argues that the failure of recent compensatory education efforts to produce lasting effects on children’s IQ and achievement suggests that the premises on which these efforts have been based should be reexamined. He begins by questioning a central notion upon which these and other educational programs have recently been based: that IQ differences are almost entirely a result of environmental differences and the cultural bias of IQ tests. After tracing the history of IQ tests, Jensen carefully defines the concept of IQ, pointing out that it appears as a common factor in all tests that have been devised thus far to tap higher mental processes. Having defined the concept of intelligence and related it to other forms of mental ability, Jensen employs an analysis of variance model to explain how IQ can be separated into genetic and environmental components. He then discusses the concept of “heritability”, a statistical tool for assessing the degree to which individual differences in a trait like intelligence can be accounted for by genetic factors. He analyzes several lines of evidence which suggest that the heritability of intelligence is quite high (ie. genetic factors are much more important than environmental factors in producing IQ differences). After arguing that environmental factors are not nearly as important in determining IQ as are genetic factors, Jensen proceeds to analyze the environmental influences which may be most critical in determining IQ. He concludes that prenatal influences may well contribute the largest environmental influence on IQ. He then discusses evidence which suggests that social class and racial variations in intelligence cannot be accounted for by differences in environment but must be attributed partially to genetic differences. After he has discussed the influence on the distribution of IQ in a society on its functioning, Jensen examines in detail the results of educational programs for young children, and finds that the changes in IQ produced by these programs are generally small. A basic conclusion of Jensen’s discussion of the influence of environment on IQ is that environment acts as a “threshold variable.” Extreme environmental deprivation can keep the child from performing up to his genetic potential, but an enriched educational program cannot push the child above that potential. Finally, Jensen examines other mental abilities that might be capitalized on in an educational program, discussing recent findings on diverse patterns of mental abilities between ethnic groups and his own studies of associative learning abilities that are independent of social class. He concludes that educational attempts to boost IQ have been misdirected and that the educational process should focus on teaching much more specific skills. He argues that this will be accomplished most effectively if educational methods are developed which are based on other mental abilities besides IQ.