developingintelligence | July 14, 2008Most readers of this blog are probably familiar with "unilateral neglect," one of several behavioral manifestations of brain damage to the parietal lobe. Perhaps fewer readers are aware of other findings from unilateral neglect patients which are often omitted from classic descriptions of this syndrome.
First, the obligatory illustration of unilateral neglect; here's what happens when you ask a patient with right parietal lobe damage to copy a simple drawing of a clock and a flower:
Patients with this "unilateral" or "hemispatial" neglect are able to describe only those parts of a mental…
developingintelligence | July 8, 2008How would an ideal behavioral method for cognitive enhancement actually affect the brain? Perhaps cognitive enhancement would be accompanied by more activity in the prefrontal cortex, indicating more successful engagement of control - or perhaps by less, indicating more efficient processing? Perhaps it would be accompanied by a transition from prefrontal activation to parietal activation, suggesting more automatic processing of task information. Perhaps it would make representations in prefrontal cortex more abstract and generalizable, or perhaps it would cause representations there to…
developingintelligence | July 7, 2008Training high-level cognition or "executive function" is not always successful. Interestingly, some of the least robust training effects come from one of psychology's most robust paradigms - the Stroop task.
The Stroop task is simple to describe, but difficult to complete. In its simplest form, subjects must name the ink color in which a word is written but ignore potentially conflicting information from the meaning of the word itself. This typically results in three types of trials: neutral trials (where word meaning is irrelevant to the ink color"LOT"), incongruent trials (where word…
developingintelligence | July 2, 2008Klaus Oberauer has a fascinating paper from 2006 which seems to have been ignored by the cognitive training community. Oberaurer demonstrates how improper counterbalancing, ignorance of the power-law of practice, and confounds in the design of memory load tasks can substantially misconstrue the real effects of training on performance. This work has implications for the interpretation of improvements in n-back performance as a function of training, which has become a feature of several new websites in the wake of a study showing fluid intelligence is enhanced after n-back training.
In 2004,…
developingintelligence | July 2, 2008Self-selection refers to the fact that certain kinds of people may be drawn to certain kinds of lifestyles or practices (including participation in human research). When the effects of those lifestyles/practices are observed scientifically, they are confounded with myriad other factors which also characterize that group. For example, in the context of meditation studies, it is possible that meditation in the realm of 10-50,000 hours has beneficial effects, but is also difficult to prove the important factor is not all other characteristics of such avid meditators (for example, their…
developingintelligence | July 1, 2008How does meditation experience functionally change the brain, and what effects does this have on distractibility? These are the questions addressed in a 2006 PNAS article from Brefczynski-Lewis et al, who compare expert meditators (between 10,000 and 54,000 hours of meditation experience) with two age-matched novice groups, one paid to help control for any motivation-related differences between groups.
As compared to a resting condition, the neural correlates of meditation changed with experience according to a U-shaped function: those with the most and least meditation experience show…
developingintelligence | June 30, 2008Attention training through meditation can reduce the duration of the "attentional blink" - in which detection of a first rare target causes people to be unaware of a second target presented soon after the first - according to research by Slagter et al from PLoSBiology.
The attention blink effect is "attentional" because it only occurs when subjects actually detect the first target, and therefore reflects some kind of a refractory period for attentional orienting: consider it the duration of the "blink" of the mind's eye. You can try it here.
Slagter et al administered pre- and post-training…
developingintelligence | June 27, 2008As discussed earlier this week, meditation may be an alternative form of brain training - or "brain untraining" - that shows transfer to tasks requiring cognitive control. There have been a few updates to this fascinating line of research, not least of which is a fascinating paper by Amishi Jha and colleagues from the University of Pennsylvania. They showed that relative to a control group, meditation influences particular components of attention in ways that are compatible with beliefs long held in the meditation community.
In particular, Jha et al focus on mindfulness meditation, which is…
developingintelligence | June 25, 2008In a fascinating review of the cognitive neuroscience of attention, authors Raz and Buhle note that most research on attention focuses on defining situations in which it is no longer required to perform a task - in other words, the automatization of thought and behavior. Yet relatively few studies focus on whether thought and behavior can be de-automatized - or, as I might call it if I were asking for trouble, deprogrammed.
What would count as deprogramming? For example, consider the Stroop task, where subjects must name the ink color of each word in a list of color words (e.g., "red" might…
developingintelligence | June 17, 2008Kevin at IQ's Corner has blogged about a new paper in PNAS showing that "working memory" training can improve measures of fluid intelligence - a capacity long thought to be relatively insensitive to experience, and intricately tied to the most complex human cognitions like reasoning, planning, and abstraction in novel contexts.
Jaeggi et al., posit that no empirical evidence shows "computer games enhance anything beyond task-specific performance and selective visuospatial attention" (which must bother our friends at Lumosity & SharpBrains - sigh), and highlight the concern that by "…
developingintelligence | June 16, 2008In a recent issue of Science, Dahlin et al report the results of an executive function training paradigm focused on the process of mental updating. "Updating" is thought to be one of the core executive functions (as determined through confirmatory factor analysis), is thought to rely on the striatum (as determined through computational neural network modeling), and provides the dynamic gating capacity to working memory which may allow for "perceptual filtering" in which some items are attended and others ignored (as confirmed with neuroimaging).
24 subjects matched for age, education,…
developingintelligence | June 13, 2008Children can be notoriously constrained to the present, but a fascinating article in JEP:HPP by Vallesi & Shallice shows exactly how strong that constraint can be: in a study with 4-11 year-olds, they show that only children older than about 5 years will take advantage of additional time provided for them to prepare for a simple task.
Among adults, this finding is part of the literature on "foreperiod phenomena." Classically, this refers to the finding that reaction times are disproportionately faster with longer intervals between a warning stimulus and an "imperative" stimulus (e.g…
developingintelligence | June 12, 2008Could something be perceived if there is no sensory system which is dedicated to it? For everyone except parapsychologists, the obvious answer is no - but this raises questions about the ability to perceive short temporal intervals, for which there appears to be no dedicated sensory system.
In their newly in-press TICS article, Ivry and Schlerf review the state of the art in cognitive modeling of time perception - perhaps the most basic form of perception which has no sensory system dedicated to it.
Ivry and Schlerf review the attractive qualities of time perception modules, such as the…
developingintelligence | June 9, 2008Working memory - the ability to hold information "in mind" in the face of environmental interference - has traditionally been associated with the prefrontal cortices (PFC), based primarily on data from monkeys. High resolution functional imaging (such as fMRI) have revealed that PFC is just one part of a larger working memory network, notably including the parietal cortex, which has long been the focus of research in the visual domain, and is primarily thought to carry out spatial computations.
What role might such spatial computations have in working memory? Wendelken, Bunge & Carter…
developingintelligence | June 6, 2008A variety of new cognitive neuroscience shows how our ability to ignore distractions - to "perceptually filter", in a sense - is based on a ventral attentional network, is related to working memory, and may be involved in putative inhibitory tasks.
First, a little background. In 2004, Vogel & Machizawa showed that some people may appear to have a lower working memory capacity merely because they are unable to filter distractions from their environment. The authors found a particular wave of electrical activity on the scalp - over the parietal cortex - which corresponded to subjects'…
developingintelligence | May 23, 2008The organization of the human prefrontal cortex (PFC) is a lasting mystery in cognitive neuroscience, but not for lack of answers - the issue is deciding among them, since all seem to characterize prefrontal function in very different but apparently equally-valid ways. If this mystery were resolved, it could revolutionize cognitive neuroscience and neuropsychology as well as education and artificial intelligence - prefrontal cortex is crucial for the most high-level cognitive abilities we know of, including the executive functions, but no existing theory of intelligence specifies the exact…
developingintelligence | May 22, 2008"It has attained a certain mystique in the physical and biological sciences because it manages to be both rare and ubiquitous. Examples [...] are found in quasar luminosity, tide and river height, traffic flow, and human heartbeat..." (Gilden & Hannock)
Since the mid-90s, a small group of cognitive psychologists have turned their attention to variability in human performance which cannot be explained by existing theories and appears not to be affected by experimental manipulations. "One-over-f" or "pink" noise refers to one way in which human performance across time correlates with…
developingintelligence | May 21, 2008New research from Wharton and the Carlson School shows that a methodologically-appealing measure of impulsivity - hyperbolic discounting rate - may actually reflect a systematic "skew" in the way people perceive time.
Previous work has shown that people tend to decreasingly discount the usefulness or appeal of a reward with increasing delays; that is, a reward provided now is more appealing than a reward provided 1 week or 1 month from now, but that change in appeal is nonlinear (hyperbolic) across time. In other words, people prefer to behave impatiently now, but prefer to act more and…
developingintelligence | May 14, 2008In 2001, Yamamoto and Kitazawa showed that the perception of temporal order can be reversed when subjects cross their hands. Subjects closed their eyes and had their hands mechanically touched in quick succession (with stimuli separated in time by a variable amount - from 1500 ms to 0 ms). Subjects were asked to raise the finger of the hand that was first stimulated. The results showed that subjects were accurate in reporting the temporal order of these stimuli when separated by as little as 70ms - but when their arms were crossed, subjects showed a tendency to reverse the temporal order…
developingintelligence | May 13, 2008Your ability to control thought and behavior relative to your peers - a set of capacities known as "executive functions" - is almost entirely genetic in origin, according to a newly in-press paper from Friedman et al. Over 560 twins completed tests to measure fundamental components of these executive functions, and the results were analyzed in terms of how similar identical twins performed to one another relative to fraternal twins (all twins in the study were reared together). Astonishingly, the results show that the variance common to all executive functions is correlated roughly twice as…