cognitive neuroscience
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…
mixingmemory | June 19, 2008We already know that mirror neurons are responsible for social interaction (except when they're not), meaning, art, religion, sports, dinosaurs, sun spots, Marxism, post-it notes, freeze-dried fruit, Harleys, and and Firefox 3.0, so it's not at all surprising that we're now learning that they're responsible for sex as well. Oh, I know, I know, we'd already learned that mirror neurons were responsible for sexual orientation, as I mentioned like two years ago, but we're just now learning that they're responsible for all sex. But we should have known already, right?
Let's start with the sexual…
mixingmemory | June 18, 2008Blogs and the mainstream media have been filled with neuroscience news lately. First we learned that sarcasm happens in the brain, and then that sexual orientation is in the brain too. There was even an attempt (sarcastic, I hope) to account for sports fandom with mirror neurons (I've heard that the actual reason we like watching sports is because we have retinas(1)). Neuroscience is all the rage, man.
I haven't, however, seen much coverage of what I think is the coolest recent neuroscience finding. That finding was reported in a paper in the May 30 issue of Science, titled "Predicting Human…
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 27, 2008In this poster, Bastos, Mullen and colleagues show that they can analyze electrical oscillations on the scalp of human subjects and predict how quickly they will respond in a simple target detection task. They do this by an interesting method known as the Steady State Visual Evoked Potential (SSVEP), otherwise known as "frequency tagging": the basic idea is that visual stimuli can be flickered onscreen at various frequencies, and that those frequencies are detectable on the scalp - particularly if they are being actively attended.
When the frequency of the flickering stimulus is most strong…
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…
developingintelligence | May 12, 2008Time pervades our understanding of the world - we use it to coordinate our movements, to perceive motion, to plan our behaviors, and perhaps even to understand causality.
But it is an under-appreciated factor in cognition. Even in the domain of the well-understood visual system, few realize that neurons in visual cortex are tuned not only for sensitivity to visual input of particular orientations, but also tuned also to time - in terms of temporal contrast.
Johnston, Arnold and Nishida were able to manipulate this temporal tuning with a relatively simple method. The authors presented a…
developingintelligence | May 9, 2008Our ability to suppress unwanted thoughts and behaviors is thought to be related to a process known as "inhibition," whereby ventrolateral regions of prefrontal cortex (vlPFC) actively suppress inappropriate representations. A 2001 study by Sakagami et al. recorded firing data from neurons in the vlPFC to determine the exact mechanism by which this might occur.
The authors begin by noting that previous studies of vlPFC have found that a majority of neurons "responded to a stimulus that instructed execution, not suppression, of a behavioral response." This view is consistent with that of…
developingintelligence | May 8, 2008Does the resolution or precision of human memory change with its available capacity? In other words, can you remember fewer items with greater precision than you can remember more items?
Contradicting intuition, a new paper from yesterday's issue of Nature shows that all items are stored in memory with equal resolution, regardless of the number of items stored. Authors Zhang & Luck first showed that subjects are equally accurate in reporting the color of a memorized item regardless of the number of other items being maintained in memory. Specifically, when subjects were asked to…
developingintelligence | May 7, 2008Complex cognition can be predicted by remarkably simple tasks. For example, the speed with which you choose one of two possible responses can reliably predict IQ. Some theories propose that this relationship is due to differences in something called "processing speed," but more recent work has shown the effect is really due to the slowness of your slowest reaction times on such simple tasks. Known as the "worst performance rule," this can be revealed through various RT distribution decomposition techniques (e.g., "binning" of reaction times or ex-gaussian analysis).
A particular class of…
mixingmemory | May 4, 2008Then listen to this set of lectures from the 2007 Advanced Neuroimaging Summer School at UCLA.