Human information processing is characterized by bottlenecks that constrain throughput. These bottlenecks limit both what we can perceive and what we can act on in multitask settings. Although perceptual and response limitations are often attributed to independent information processing bottlenecks, it has recently been suggested that a common attentional limitation may be responsible for both. To date, however, evidence supporting the existence of such a “unified” bottleneck has been mixed. Here, we tested the unified bottleneck hypothesis using time-resolved fMRI. Experiment 1 isolated brain regions involved in the response selection bottleneck that limits speeded dual-task performance. These same brain regions were not only engaged by a perceptual encoding task in Experiment 2, their activity also tracked delays to a speeded decision-making task caused by concurrent perceptual encoding (Experiment 3). We conclude that a unified attentional bottleneck, including the inferior frontal junction, superior medial frontal cortex, and bilateral insula, temporally limits operations as diverse as perceptual encoding and decision-making.
“It's the Latency, Stupid”, (2001):
[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:]
- Fact One: Making more bandwidth is easy.
- Fact Two: Once you have bad latency you’re stuck with it.
- Fact Three: Current consumer devices have appallingly bad latency.
- 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.
“Web Bloat”, (2017-02-08):
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:
- 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.
- 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.
“Computer latency: 1977–2017”, (2017-12):
I’ve had this nagging feeling that the computers I use today feel slower than the computers I used as a kid. As a rule, I don’t trust this kind of feeling because human perception has been shown to be unreliable in empirical studies, so I carried around a high-speed camera and measured the response latency of devices I’ve run into in the past few months. These are tests of the latency between a keypress and the display of a character in a terminal (see appendix for more details)…If we look at overall results, the fastest machines are ancient. Newer machines are all over the place. Fancy gaming rigs with unusually high refresh-rate displays are almost competitive with machines from the late 70s and early 80s, but “normal” modern computers can’t compete with thirty to forty year old machines.
…Almost every computer and mobile device that people buy today is slower than common models of computers from the 70s and 80s. Low-latency gaming desktops and the iPad Pro can get into the same range as quick machines from thirty to forty years ago, but most off-the-shelf devices aren’t even close.
If we had to pick one root cause of latency bloat, we might say that it’s because of “complexity”. Of course, we all know that complexity is bad. If you’ve been to a non-academic non-enterprise tech conference in the past decade, there’s a good chance that there was at least one talk on how complexity is the root of all evil and we should aspire to reduce complexity.
Unfortunately, it’s a lot harder to remove complexity than to give a talk saying that we should remove complexity. A lot of the complexity buys us something, either directly or indirectly. When we looked at the input of a fancy modern keyboard vs. the Apple 2 keyboard, we saw that using a relatively powerful and expensive general purpose processor to handle keyboard inputs can be slower than dedicated logic for the keyboard, which would both be simpler and cheaper. However, using the processor gives people the ability to easily customize the keyboard, and also pushes the problem of “programming” the keyboard from hardware into software, which reduces the cost of making the keyboard. The more expensive chip increases the manufacturing cost, but considering how much of the cost of these small-batch artisanal keyboards is the design cost, it seems like a net win to trade manufacturing cost for ease of programming.
“Terminal Latency”, (2017-07-18):
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—terminal.app 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.
2001-demarco-peopleware-whymeasureperformance.pdf: “Peopleware: Why Measure Performance”, Tom DeMarco, Timothy Lister
“Programmer information needs after memory failure”, (2012-06-11):
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.
2013-elpus.pdf: “Is It the Music or Is It Selection Bias? A Nationwide Analysis of Music and Non-Music Students’ SAT Scores”, (2013-05-21; ):
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.
Young children regularly engage in musical activities, but the effects of early music education on children’s cognitive development are unknown. While some studies have found associations between musical training in childhood and later nonmusical cognitive outcomes, few randomized controlled trials (RCTs) have been employed to assess causal effects of music lessons on child cognition and no clear pattern of results has emerged. We conducted two with preschool children investigating the cognitive effects of a brief series of music classes, as compared to a similar but non-musical form of arts instruction (visual arts classes, Experiment 1) or to a no-treatment control (Experiment 2). Consistent with typical preschool arts enrichment programs, parents attended classes with their children, participating in a variety of developmentally appropriate arts activities. After six weeks of class, we assessed children’s skills in four distinct cognitive areas in which older arts-trained students have been reported to excel: spatial-navigational reasoning, visual form analysis, numerical discrimination, and receptive vocabulary. We initially found that children from the music class showed greater spatial-navigational ability than did children from the visual arts class, while children from the visual arts class showed greater visual form analysis ability than children from the music class (Experiment 1). However, a partial replication attempt comparing music training to a no-treatment control failed to confirm these findings (Experiment 2), and the combined results of the two experiments were negative: overall, children provided with music classes performed no better than those with visual arts or no classes on any assessment. Our findings underscore the need for replication in , and suggest caution in interpreting the positive findings from past studies of cognitive effects of music instruction.
2007-gouzouasis.pdf: “The predictive relationship between achievement and participation in music and achievement in core Grade 12 academic subjects”, (2007-01-31; ):
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.
2004-costagiomi.pdf: “Effects of Three Years of Piano Instruction on Children’s Academic Achievement, School Performance and Self-Esteem”, (2004-04-01; ):
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.
1993-schneider.pdf: “Chess Expertise and Memory for Chess Positions in Children and Adults”, (1993-12-01; ):
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.
1969-jensen.pdf: “How Much Can We Boost IQ and Scholastic Achievement?”, (1969-05-01; ):
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.
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.
2010-schmeichel.pdf: “WM and Spontaneous ER_resubmission”, Joseph Weaver
2010-alloway.pdf: “Investigating the predictive roles of working memory and IQ in academic attainment”, Tracy Packiam Alloway, Ross G. Alloway
Intelligence quotient (IQ) is a standardized measure of human intellectual capacity that takes into account a wide range of cognitive skills. IQ is generally considered to be stable across the lifespan, with scores at one time point used to predict educational achievement and employment prospects in later years. Neuroimaging allows us to test whether unexpected longitudinal fluctuations in measured IQ are related to brain development. Here we show that verbal and non-verbal IQ can rise or fall in the teenage years, with these changes in performance validated by their close correlation with changes in local brain structure. A combination of structural and functional imaging showed that verbal IQ changed with grey matter in a region that was activated by speech, whereas non-verbal IQ changed with grey matter in a region that was activated by finger movements. By using longitudinal assessments of the same individuals, we obviated the many sources of variation in brain structure that confound cross-sectional studies. This allowed us to dissociate neural markers for the two types of IQ and to show that general verbal and non-verbal abilities are closely linked to the sensorimotor skills involved in learning. More generally, our results emphasize the possibility that an individual’s intellectual capacity relative to their peers can decrease or increase in the teenage years. This would be encouraging to those whose intellectual potential may improve, and would be a warning that early achievers may not maintain their potential.
2011-morrison.pdf: “Does working memory training work? The promise and challenges of enhancing cognition by training working memory”, (2010-11-17; ):
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]
“Generalizing From One Example”, (2009-04-28):
[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/prosospagnosia, 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.]
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.
Studies that examine the effects of exercise on children’s intelligence, cognition, or academic achievement were reviewed and results were discussed in light of (a) contemporary cognitive theory development directed toward exercise, (b) recent research demonstrating the salutary effects of exercise on adults’ cognitive functioning, and (c) studies conducted with animals that have linked physical activity to changes in neurological development and behavior. Similar to adults, exercise facilitates children’s executive function (i.e., processes required to select, organize, and properly initiate goal-directed actions). Exercise may prove to be a simple, yet important, method of enhancing those aspects of children’s mental functioning central to cognitive development.
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, N. F Krebs, K. M Hambidge
2013-kurzban.pdf: “An opportunity cost model of subjective effort and task performance”, (2013-12-04; ):
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.
2010-moe.pdf: “Beyond genetics in Mental Rotation Test performance”, Angelica Moè, Francesca Pazzaglia
“Putting brain training to the test”, (2010):
‘Brain training’, or the goal of improved cognitive function through the regular use of computerized tests, is a multimillion-pound industry, yet in our view scientific evidence to support its efficacy is lacking. Modest effects have been reported in some studies of older individuals and preschool children, and video-game players outperform non-players on some tests of visual attention. However, the widely held belief that commercially available computerized brain-training programs improve general cognitive function in the wider population in our opinion lacks empirical support. The central question is not whether performance on cognitive tests can be improved by training, but rather, whether those benefits transfer to other untrained tasks or lead to any general improvement in the level of cognitive functioning. Here we report the results of a six-week online study in which 11,430 participants trained several times each week on cognitive tasks designed to improve reasoning, memory, planning, visuospatial skills and attention. Although improvements were observed in every one of the cognitive tasks that were trained, no evidence was found for transfer effects to untrained tasks, even when those tasks were cognitively closely related.
A neural network underlying attentional control involves the anterior cingulate in addition to lateral prefrontal areas. An important development of this network occurs between 3 and 7 years of age. We have examined the efficiency of attentional networks across age and after 5 days of attention training (experimental group) compared with different types of no training (control groups) in 4-year-old and 6-year-old children. Strong improvement in executive attention and intelligence was found from ages 4 to 6 years. Both 4- and 6-year-olds showed more mature performance after the training than did the control groups. This finding applies to behavioral scores of the executive attention network as measured by the attention network test, event-related potentials recorded from the scalp during attention network test performance, and intelligence test scores. We also documented the role of the temperamental factor of effortful control and the DAT1 gene in individual differences in attention. Overall, our data suggest that the executive attention network appears to develop under strong genetic control, but that it is subject to educational interventions during development.
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.
2008-jaeggi-transfer.pdf: “Microsoft PowerPoint - Descriptive Data - Jaeggi et al 2008 - Reasoning.pptx”, Susanne Jaeggi
2009-qiu.pdf: “Study on Improving Fluid Intelligence through Cognitive Training System Based on Gabor Stimulus”, Feiyue Qiu, Qinqin Wei, Liying Zhao, Lifang Lin
Systematic reviews (SRs) of TCM have become increasingly popular in China and have been published in large numbers. This review provides the first examination of epidemiological characteristics of these SRs as well as compliance with the PRISMA and AMSTAR guidelines.
To examine epidemiological and reporting characteristics as well as methodological quality of SRs of TCM published in Chinese journals.
Four Chinese databases were searched (CBM, CSJD, CJFD and Wanfang Database) for SRs of TCM, from inception through Dec 2009. Data were extracted into Excel spreadsheets. The PRISMA and AMSTAR checklists were used to assess reporting characteristics and methodological quality, respectively.
A total of 369 SRs were identified, most (97.6%) of which used the terms systematic review or meta-analysis in the title. None of the reviews had been updated. Half (49.8%) were written by clinicians and nearly half (47.7%) were reported in specialty journals. The impact factors of 45.8% of the journals published in were zero. The most commonly treated conditions were diseases of the circulatory and digestive disease. Funding sources were not reported for any reviews. Most (68.8%) reported information about quality assessment, while less than half (43.6%) reported assessing for publication bias. Statistical mistakes appeared in one-third (29.3%) of reviews and most (91.9%) did not report on conflict of interest.
While many SRs of TCM interventions have been published in Chinese journals, the quality of these reviews is troubling. As a potential key source of information for clinicians and researchers, not only were many of these reviews incomplete, some contained mistakes or were misleading. Focusing on improving the quality of SRs of TCM, rather than continuing to publish them in great quantity, is urgently needed in order to increase the value of these studies.
2010-jaeggi.pdf: “The relationship between n-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
2012-studerluethi.pdf: “Influence of neuroticism and conscientiousness on working memory training outcome”, Barbara Studer-Luethi, Susanne M. Jaeggi, Martin Buschkuehl, Walter J. Perrig
2013-stephenson.pdf: “Improved matrix reasoning is limited to training on tasks with a visuospatial component”, Clayton L. Stephenson, Diane F. Halpern
2011-jaeggi-poster.pdf: “The Title of the Poster”
So-called ‘brain-training’ programs are a huge commercial success. However, empirical evidence regarding their effectiveness and generalizability remains equivocal. This study investigated whether brain-training (working memory [WM] training) improves cognitive functions beyond the training task (transfer effects), especially regarding the control of emotional material since it constitutes much of the information we process daily. Forty-five participants received WM training using either emotional or neutral material, or an undemanding control task. WM training, regardless of training material, led to transfer gains on another WM task and in fluid intelligence. However, only brain-training with emotional material yielded transferable gains to improved control over affective information on an emotional Stroop task. The data support the reality of transferable benefits of demanding WM training and suggest that transferable gains across to affective contexts require training with material congruent to those contexts. These findings constitute preliminary evidence that intensive cognitively demanding brain-training can improve not only our abstract problem-solving capacity, but also ameliorate cognitive control processes (e.g. decision-making) in our daily emotive environments.
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, Christine Stelzel
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-chuderski.pdf: “The broad factor of working memory is virtually isomorphic to fluid intelligence tested under time pressure”, Adam Chuderski
2010-seidler.pdf: “M-CASTL Synthesis Report”, SBA
Although long considered a natively endowed and fixed trait, working memory (WM) ability has recently been shown to improve with intensive training. What remains controversial and poorly understood, however, are the neural bases of these training effects and the extent to which WM training gains transfer to other cognitive tasks. Here we present evidence from human electrophysiology (EEG) and simultaneous transcranial magnetic stimulation and EEG that the transfer of WM training to other cognitive tasks is supported by changes in task-related effective connectivity in frontoparietal and parieto-occipital networks that are engaged by both the trained and transfer tasks. One consequence of this effect is greater efficiency of stimulus processing, as evidenced by changes in EEG indices of individual differences in short-term memory capacity and in visual search performance. Transfer to search-related activity provides evidence that something more fundamental than task-specific strategy or stimulus-specific representations has been learned. Furthermore, these patterns of training and transfer highlight the role of common neural systems in determining individual differences in aspects of visuospatial cognition.
Recent studies have reported improvements in a variety of cognitive functions following sole working memory (WM) training. In spite of the emergence of several successful training paradigms, the scope of transfer effects has remained mixed. This is most likely due to the heterogeneity of cognitive functions that have been measured and tasks that have been applied. In the present study, we approached this issue systematically by investigating transfer effects from WM training to different aspects of. Our training task was a demanding WM task that requires simultaneous performance of a visual and an auditory n-back task, while the transfer tasks tapped WM updating, coordination of the performance of multiple simultaneous tasks (i.e., dual-tasks) and sequential tasks (i.e., task switching), and the temporal distribution of attentional processing. Additionally, we examined whether WM training improves reasoning abilities; a hypothesis that has so far gained mixed support. Following training, participants showed improvements in the trained task as well as in the transfer WM updating task. As for the other , trained participants improved in a task switching situation and in attentional processing. There was no transfer to the dual-task situation or to reasoning skills. These results, therefore, confirm previous findings that WM can be trained, and additionally, they show that the training effects can generalize to various other tasks tapping on .
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.
2013-heinzel.pdf: “Working memory training improvements and gains in non–trained cognitive tasks in young and older adults”, (2013-05-02; ):
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,]
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.
2013-smith.pdf: “Exploring the effectiveness of commercial and custom-built games for cognitive training”, Shamus P. Smith, Marina Stibric, David Smithson
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-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, Scott A. Weems, Vanessa Smith, Steven Bobb, Michael F. Bunting, Michael R. Dougherty
2013-colom.pdf: “Adaptive n-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, Kenia Martínez, Miguel Burgaleta, M. A. Quiroga, Sherif Karama, Richard J. Haier, Paul M. Thompson, Susanne M. Jaeggi
“Transfer after Working Memory Updating Training”, (2015-09-01):
During the past decade, working memory training has attracted much interest. However, the training outcomes have varied between studies and methodological problems have hampered the interpretation of results. The current study examined transfer after working memory updating training by employing an extensive battery of pre-post cognitive measures with a focus on near transfer. Thirty-one healthy Finnish young adults were randomized into either a working memory training group or an active control group. The working memory training group practiced with three working memory tasks, while the control group trained with three commercial computer games with a low working memory load. The participants trained thrice a week for five weeks, with one training session lasting about 45 minutes. Compared to the control group, the working memory training group showed strongest transfer to an n-back task, followed by working memory updating, which in turn was followed by active working memory capacity. Our results support the view that working memory training produces near transfer effects, and that the degree of transfer depends on the cognitive overlap between the training and transfer measures.
Although some studies have shown that cognitive training can produce improvements to untrained cognitive domains (far transfer), many others fail to show these effects, especially when it comes to improving fluid intelligence. The current study was designed to overcome several limitations of previous training studies by incorporating training expectancy assessments, an active control group, and “Mind Frontiers,” a video game-based mobile program comprised of six adaptive, cognitively demanding training tasks that have been found to lead to increased scores in fluid intelligence (Gf) tests. We hypothesize that such integrated training may lead to broad improvements in cognitive abilities by targeting aspects of working memory, executive function, reasoning, and problem solving. Ninety participants completed 20 hour-and-a-half long training sessions over four to five weeks, 45 of whom played Mind Frontiers and 45 of whom completed visual search and change detection tasks (active control). After training, the Mind Frontiers group improved in working memory n-back tests, a composite measure of perceptual speed, and a composite measure of reaction time in reasoning tests. No training-related improvements were found in reasoning accuracy or other working memory tests, nor in composite measures of episodic memory, selective attention, divided attention, and multi-tasking. Perceived self-improvement in the tested abilities did not differ between groups. A general expectancy difference in problem-solving was observed between groups, but this perceived benefit did not correlate with training-related improvement. In summary, although these findings provide modest evidence regarding the efficacy of an integrated cognitive training program, more research is needed to determine the utility of Mind Frontiers as a cognitive training tool.
Enhancing cognitive ability is an attractive concept, particularly for middle-aged adults interested in maintaining cognitive functioning and preventing age-related declines. Computerized working memory training has been investigated as a safe method of cognitive enhancement in younger and older adults, although few studies have considered the potential impact of working memory training on middle-aged adults. This study investigated dual n-back working memory training in healthy adults aged 30–60. Fifty-seven adults completed measures of working memory, processing speed, and fluid intelligence before and after a 5-week web-based dual n-back or active control (processing speed) training program. Results: Repeated measures multivariate analysis offailed to identify improvements across the three cognitive composites, working memory, processing speed, and fluid intelligence, after training. Follow-up Bayesian analyses supported null findings for training effects for each individual composite. Findings suggest that dual n-back working memory training may not benefit working memory or fluid intelligence in healthy adults. Further investigation is necessary to clarify if other forms of working memory training may be beneficial, and what factors impact training-related benefits, should they occur, in this population.
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
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 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,, attention, learning disabilities]
Training working memory (WM) improves performance on untrained cognitive tasks and alters functional activity. However, WM training’s effects on gray matter morphology and a wide range of cognitive tasks are still unknown. We investigated this issue using voxel-based morphometry (VBM), various psychological measures, such as non-trained WM tasks and a creativity task, and intensive adaptive training of WM using mental calculations (IATWMMC), all of which are typical WM tasks. IATWMMC was associated with reduced regional gray matter volume in the bilateral fronto-parietal regions and the left superior temporal gyrus. It improved verbal letter span and complex arithmetic ability, but deteriorated creativity. These results confirm the training-induced plasticity in psychological mechanisms and the plasticity of gray matter structures in regions that have been assumed to be under strong genetic control.
2013-vartanian.pdf: “Working memory training is associated with lower prefrontal cortex activation in a divergent thinking task”, (2013-04-16; ):
- 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 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.
2010-colom.pdf: “Improvement in working memory is not related to increased intelligence scores”, Roberto Colom, Mª Ángeles Quiroga, Pei Chun Shih, Kenia Martínez, Miguel Burgaleta, Agustín Martínez-Molina, Francisco J. Román, Laura Requena, Isabel Ramírez
2009-karbach.pdf: “How useful is executive control training? Age differences in near and far transfer of task-switching training”, (2009-10-14; ):
Althoughcan 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. Three 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.
2008-karbach.pdf: “CAC08_Karbach”, dast003
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
2002-klauer.pdf: “Inducing Inductive Reasoning: Does It Transfer to Fluid Intelligence?”, Klauer, K. J., et al.
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
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-parker.pdf: “Reduced misinformation effects following saccadic bilateral eye movements”, Andrew Parker, Sharon Buckley, Neil Dagnall
2009-rodriguezjimenez.pdf: “Differential dorsolateral prefrontal cortex activation during a verbal n-back task according to sensory modality”, (2009-12-14; ):
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]
“Fractionating Human Intelligence”, (2012-12-20):
- 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.
2009-agarwal.pdf: “The Age of Reason: Financial Decisions over the Life Cycle and Implications for Regulation”, (2009; ):
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.
2009-agarwal-slides.pdf: “Microsoft PowerPoint - Age of Reason”, decosta
Background: 100 years after the first description, Alzheimer’s disease is one of the most disabling and burdensome health conditions worldwide. We used the Delphi consensus method to determine dementia prevalence for each world region.
Methods: 12 international experts were provided with a systematic review of published studies on dementia and were asked to provide prevalence estimates for every WHO world region, for men and women combined, in 5-year age bands from 60 to 84 years, and for those aged 85 years and older. UN population estimates and projections were used to estimate numbers of people with dementia in 2001, 2020, and 2040. We estimated incidence rates from prevalence, remission, and mortality.
Findings: Evidence from well-planned, representative epidemiological surveys is scarce in many regions. We estimate that 24.3 million people have dementia today, with 4.6 million new cases of dementia every year (one new case every 7 seconds). The number of people affected will double every 20 years to 81.1 million by 2040. Most people with dementia live in developing countries (60% in 2001, rising to 71% by 2040). Rates of increase are not uniform; numbers in developed countries are forecast to increase by 100% between 2001 and 2040, but by more than 300% in India, China, and their south Asian and western Pacific neighbours.
Interpretation: We believe that the detailed estimates in this paper constitute the best currently available basis for policymaking, planning, and allocation of health and welfare resources.
Background: Cognitive impairment without dementia is associated with increased risk for disability, increased health care costs, and progression to dementia. There are no population-based prevalence estimates of this condition in the United States.
Objective: To estimate the prevalence of cognitive impairment without dementia in the United States and determine longitudinal cognitive and mortality outcomes.
Design: Longitudinal study from July 2001 to March 2005.
Setting: In-home assessment for cognitive impairment.
Participants: Participants in ADAMS (Aging, Demographics, and Memory Study) who were age 71 years or older drawn from the nationally representative HRS (Health and Retirement Study). Of 1770 selected individuals, 856 completed initial assessment, and of 241 selected individuals, 180 completed 16- to 18-month follow-up assessment.
Measurements: Assessments, including neuropsychological testing, neurologic examination, and clinical and medical history, were used to assign a diagnosis of normal cognition, cognitive impairment without dementia, or dementia. National prevalence rates were estimated by using a population-weighted sample.
Results: In 2002, an estimated 5.4 million people (22.2%) in the United States age 71 years or older had cognitive impairment without dementia. Prominent subtypes included prodromal Alzheimer disease (8.2%) and cerebrovascular disease (5.7%). Among participants who completed follow-up assessments, 11.7% with cognitive impairment without dementia progressed to dementia annually, whereas those with subtypes of prodromal Alzheimer disease and stroke progressed at annual rates of 17% to 20%. The annual death rate was 8% among those with cognitive impairment without dementia and almost 15% among those with cognitive impairment due to medical conditions.
Limitations: Only 56% of the nondeceased target sample completed the initial assessment. Population sampling weights were derived to adjust for at least some of the potential bias due to nonresponse and attrition.
Conclusion: Cognitive impairment without dementia is more prevalent in the United States than dementia, and its subtypes vary in prevalence and outcomes.
1999-fratiglioni.pdf: “Drugs and Aging 15: 365-375, Nov 1999”, Fratiglioni L, De Ronchi D, Ag;auuero-Torres H
The subjective sense of future time plays an essential role in human motivation. Gradually, time left becomes a better predictor than chronological age for a range of cognitive, emotional, and motivational variables. Socioemotional selectivity theory maintains that constraints on time horizons shift motivational priorities in such a way that the regulation of emotional states becomes more important than other types of goals. This motivational shift occurs with age but also appears in other contexts (for example, geographical relocations, illnesses, and war) that limit subjective future time.
Cross-sectional age differences in the Big Five personality traits were investigated using 2 large datasets from Great Britain and Germany: the British Household Panel Study (BHPS; N > or = 14,039) and the German Socio-Economic Panel Study (GSEOP; N > or = 20,852). Participants, who ranged in age from 16 to the mid-80s, completed a 15-item version of the Big Five Inventory (e.g., John & Srivastava, 1999) in either 2005 or 2006. The observed age trends were generally consistent across both datasets. Extraversion and Openness were negatively associated with age, whereas Agreeableness was positively associated with age. Average levels of were highest for participants in middle age. The only exception was Neuroticism, which was slightly negatively associated with age in the BHPS and slightly positively associated with age in the GSEOP. Neither gender nor education level were consistent moderators of age differences in the Big Five.
2007-danigelis.pdf: “Population Aging, Intracohort Aging, and Sociopolitical Attitudes”, (2007-10-01; ):
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 thatintracohort 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 present study investigated whether an intervention aimed to increase cognitive ability in older adults also changes the personality trait of openness to experience. Older adults completed a 16-week program in inductive reasoning training supplemented by weekly crossword and Sudoku puzzles. Changes in openness to experience were modeled across four assessments over 30 weeks using latent growth curve models. Results indicate that participants in the intervention condition increased in the trait of openness compared with a waitlist control group. The study is one of the first to demonstrate that personality traits can change through nonpsychopharmocological interventions.
Previous research suggests that, in reaction time (RT) measures of episodic memory retrieval, the unique effects of adult age are relatively small compared to the effects aging shares with more elementary abilities such as perceptual speed. Little is known, however, regarding the mechanisms of perceptual speed. We used diffusion tensor imaging (DTI) to test the hypothesis that white matter integrity, as indexed by fractional anisotropy (FA), serves as one mechanism of perceptual slowing in episodic memory retrieval. Results indicated that declines in FA in the pericallosal frontal region and in the genu of the corpus callosum, but not in other regions, mediated the relationship between perceptual speed and episodic retrieval RT. This relation held, though to a different degree, for both hits and correct rejections. These findings suggest that white matter integrity in prefrontal regions is one mechanism underlying the relation between individual differences in perceptual speed and episodic retrieval.
Cross-sectional comparisons have consistently revealed that increased age is associated with lower levels of cognitive performance, even in the range from 18 to 60 years of age. However, the validity of cross-sectional comparisons of cognitive functioning in young and middle-aged adults has been questioned because of the discrepant age trends found in longitudinal and cross-sectional analyses. The results of the current project suggest that a major factor contributing to the discrepancy is the masking of age-related declines in longitudinal comparisons by large positive effects associated withtest experience. Results from three methods of estimating retest effects in this project, together with results from studies comparing non-human animals raised in constant environments and from studies examining neurobiological variables not susceptible to retest effects, converge on a conclusion that some aspects of age-related cognitive decline begin in healthy educated adults when they are in their 20s and 30s.
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
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, Felipe Fregni, Jorge Leite
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, Andre R. Brunoni
An increasing concern affecting a growing aging population is working memory (WM) decline. Consequently, there is great interest in improving or stabilizing WM, which drives expanded use of brain training exercises. Such regimens generally result in temporary WM benefits to the trained tasks but minimal transfer of benefit to untrained tasks. Pairing training with neurostimulation may stabilize or improve WM performance by enhancing plasticity and strengthening WM-related cortical networks. We tested this possibility in healthy older adults. Participants received 10 sessions of sham (control) or active (anodal, 1.5 mA) tDCS to the right prefrontal, parietal, or prefrontal/parietal (alternating) cortices. After ten minutes of sham or active tDCS, participants performed verbal and visual WM training tasks. On the first, tenth, and follow-up sessions, participants performed transfer WM tasks including the spatial 2-back, Stroop, and tasks. The results demonstrated that all groups benefited from WM training, as expected. However, at follow-up 1-month after training ended, only the participants in the active tDCS groups maintained significant improvement. Importantly, this pattern was observed for both trained and transfer tasks. These results demonstrate that tDCS-linked WM training can provide long-term benefits in maintaining cognitive training benefits and extending them to untrained tasks.
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-hoy.pdf: “The effect of Î³-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
Transcranial direct current stimulation (tDCS) has been put forward as a non-pharmacological alternative for alleviating cognitive decline in old age. Although results have shown some promise, little is known about the optimal stimulation parameters for modulation in the cognitive domain. In this study, the effects of tDCS over the dorsolateral prefrontal cortex (dlPFC) on working memory performance were investigated in thirty older adults. An N-back task assessed working memory before, during and after anodal tDCS at a current strength of 1 mA and 2 mA, in addition to sham stimulation. The study used a single-blind, cross-over design. The results revealed no statistically-significant effect of tDCS on accuracy or response times during or after stimulation, for any of the current strengths. These results suggest that a single session of tDCS over the dlPFC is unlikely to improve working memory, as assessed by an N-back task, in old age.
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 tDCS conditions. Changes in WM accuracy were moderately correlated with changes in the P3 amplitude following tDCS compared to baseline levels (r = 0.34).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
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.
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”, (2016-03; ):
- We performed a (WM) enhancement with anodal tDCS (a-tDCS) in healthy and neuropsychiatric cohorts. investigating working memory
- 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 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 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, PsychINFO, 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 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]
2010-zeidan.pdf: “Mindfulness meditation improves cognition: Evidence of brief mental training”, Fadel Zeidan, Susan K. Johnson, Bruce J. Diamond, Zhanna David, Paula Goolkasian
The information processing capacity of the human mind is limited, as is evidenced by the so-called “attentional-blink” deficit: When two targets (T1 and T2) embedded in a rapid stream of events are presented in close temporal proximity, the second target is often not seen. This deficit is believed to result from competition between the two targets for limited attentional resources. Here we show, using performance in an attentional-blink task and scalp-recorded brain potentials, that meditation, or mental training, affects the distribution of limited brain resources. Three months of intensive mental training resulted in a smaller attentional blink and reduced brain-resource allocation to the first target, as reflected by a smaller T1-elicited P3b, a brain-potential index of resource allocation. Furthermore, those individuals that showed the largest decrease in brain-resource allocation to T1 generally showed the greatest reduction in attentional-blink size. These observations provide novel support for the view that the ability to accurately identify T2 depends upon the efficient deployment of resources to T1. The results also demonstrate that mental training can result in increased control over the distribution of limited brain resources. Our study supports the idea that plasticity in brain and mental function exists throughout life and illustrates the usefulness of systematic mental training in the study of the human mind.
Meditation includes the mental training of attention, which involves the selection of goal-relevant information from the array of inputs that bombard our sensory systems. One of the major limitations of the attentional system concerns the ability to process two temporally close, task-relevant stimuli. When the second of two target stimuli is presented within a half second of the first one in a rapid sequence of events, it is often not detected. This so-called “attentional-blink” deficit is thought to result from competition between stimuli for limited attentional resources. We measured the effects of intense meditation on performance and scalp-recorded brain potentials in an attentional-blink task. We found that three months of intensive meditation reduced brain-resource allocation to the first target, enabling practitioners to more often detect the second target with no compromise in their ability to detect the first target. These findings demonstrate that meditative training can improve performance on a novel task that requires the trained attentional abilities.
Intensive training in Vipassana meditation enhances one’s ability to allocate attention efficiently in order to detect visual targets accurately. Behavioral and event-related potential evidence for a causal link between behavioral training and brain plasticity in adults is shown.