cognitive neuroscience
developingintelligence | October 3, 2008What if training ourselves on one task yielded improvements in all other tasks we perform? This is the promise of the cognitive training movement, which is increasingly showing that such "far transfer" of training is indeed possible, while short of being "universal transfer." Interestingly, this phenomenon might be most likely to occur for some of the most abstract and challenging cognitive functions.
New evidence for this claim comes from an in-press article at Psychological Science, by Persson & Reuter-Lorenz. The authors used several tasks which have been shown to engage the left…
developingintelligence | September 15, 2008Much has been written about the nonspatial functions of the parietal lobe, but these nonspatial functions are rarely evaluated as to whether they are also nonmotoric or reflect some covert form of spatial attention. Establishing whether the parietal lobe has truly nonmotoric and nonspatial functions is essential for understanding why parietal cortex appears to be involved in so many different tasks. Here I've attempted to evaluate whether the parietal lobe truly has nonspatial, and perhaps also nonmotoric functions by reviewing the relevant literature...
Magnitude processing - the size…
developingintelligence | September 12, 2008Much evidence supports the idea that parietal cortex is involved in the simple maintenance of information, such as in object permanence paradigms (also here) and other tasks. This evidence is part of the justification for the "parietofrontal integration theory", which suggests that parietal areas work in concert with prefrontal regions of the brain to accomplish the maintenance and manipulation of information. Orthodoxy holds the prefrontal cortex is more involved than parietal cortex in information manipulation (eg).
However, some have suggested that the spatial transformations…
developingintelligence | September 3, 2008Visual perception is constantly challenged by visual occlusion: objects in our environment constantly obscure one another, and seem to "disappear" when in fact they are nonetheless present.
Young infants begin to demonstrate a basic understanding of "object permanence" at some point during the first six months of life. On more complex tasks, understanding of object permanence is not observed until months later, as in Piaget's A-Not-B task. Even in these more demanding tasks, however, some understanding of object permanence can be revealed by the direction in which children gaze: kids will…
developingintelligence | September 2, 2008An absence of evidence is not itself evidence for the absence of a particular effect. This simple problem - generally known as the problem of null effects - yields many difficulties in cognitive science, making it relatively easier to parcellate cognitive and neural processes into ever-finer detail than to show when two processes are identical. Recently, this problem has emerged for the wonder child of cognitive science, functional magnetic resonance imaging (fMRI). The problem in this case is how to determine whether two tasks recruit at least one of the same areas of the brain in the…
developingintelligence | August 29, 2008Is it possible to form and execute motor intentions without being aware of when those intentions were formed? Precisely this pattern was observed by among (ha!) patients with parietal damage, as reported by Sirigu et al. They showed that patients with parietal damage are specifically impaired at estimating the time they formed the intention to commit a voluntary action, although they are unimpaired on other visual and temporal aspects to the task relative to healthy controls and to patients with cerebellar damage.
The authors argue that intentions formed in prefrontal cortex may be used…
developingintelligence | August 28, 2008Ideally, our real-world behavior is strongly determined by our context, for the simple reason that some behaviors are only appropriate in some situations (e.g., eating during an internal context of hunger, or using slang during an external context of casual interaction).
Context-inappropriate behavior is often seen as a failure of cognitive control (e.g., continuing to eat when no longer hungry, or using a common slang phrase in a formal setting).
This perspective is called "context processing," based on work pioneered by Todd Braver, Dianna Barch, Jon Cohen, and others. This framework is…
developingintelligence | August 27, 2008Parietal cortex is critical for the maintenance of object information over delays. This is true both in tests of working memory (e.g., 1, 2 and 3) as well as simple visual manipulations involving the occlusion of visible objects.
A great example is this study by Olson et al., who demonstrated that neurons in human intraparietal sulcus (IPS) and middle temporal (MT) cortex increased their activity in response to objects which disappeared due to occlusion (i.e., they were hidden behind another object) relative to those which simply disappeared without an occluder. This was particularly…
developingintelligence | August 26, 2008Andersen et al discuss both the attentional and intentional aspects to the function of the intraparietal sulcus. What's the distinction between attention and intention?
First, let's talk about attention. The modal view, based on the biased competition model of Desimone and Duncan, and the Miller & Cohen model presented yesterday, is probably that prefrontal regions actively bias particular spatial locations, as represented in parietal cortex, in accord with the current task or goal.
However, some evidence apparently conflicts with this modal view: Anderson et al. review two studies…
developingintelligence | August 25, 2008People often use the concept "hand-eye coordination" without appreciating its neural basis. Evidence collected by Andersen & colleagues over the past ten years indicates that different areas of parietal cortex are recruited to represent targets which require different effectors, all using a common eye-based coordinate system. Thus these areas are precisely those which contribute to "hand-eye coordination."
In a 1999 issue of Science, Batista, Buneao, Snyder & Andersen reported that 84% of neurons recorded from the "parietal reach region" of 3 macaques showed a peculiar pattern of…
developingintelligence | August 25, 2008In their already-classic 2001 article, Miller & Cohen use a "train track" metaphor to illustrate the function of prefrontal cortex. The idea is that myriad learned associations interconnect sensory representations with motor commands (metaphorically, these are the "train tracks"). The important associations will change depending on the animal's current task (these are the "switching stations" which allow crossover between the train tracks). Thus, the role of prefrontal cortex is to bias activity in the brain (the "train") to undergo the sensory-motor transformations which are task- and…
developingintelligence | July 15, 2008To enhance any system, one first needs to identify its capacity-limiting factor(s). Human cognition is a highly complex and multiply constrained system, consisting of both independent and interdependent capacity-limitations. These "bottlenecks" in cognition are reviewed below as a coherent framework for understanding the plethora of cognitive training paradigms which are currently associated with enhancements of working memory, executive function and fluid intelligence (1,2, 3, 4, 5, 6, 7, 8, 9,
10, c.f. 11, 12, 13).
By far, the most common complaint about limitations in cognition is…
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…