developingintelligence | October 29, 2007One of the more surprising findings to emerge from the intelligence literature is that an individual's ability to think in highly complex and abstract forms is related to speed in tasks as simple as "press the lighted button." Simple reaction time tasks like this have amazing predictive power for performance on much more elaborate tasks, leading some theorists to propose that such reaction time (RT) measures grossly index the integrity or speed of processing in a way that benefits all tasks.
Interestingly, the average speed on simple RT tasks is often not as predictive as other aspects of…
developingintelligence | October 17, 2007Several have criticized my post on handedness by pointing to evidence (or hearsay) that animals do have handedness. This evidence comes in several forms:
Anecdote: "My cat plays with its right paw"
Individual or Activity-Specific Cases: "Horses reliably pick one leg to lead their galloping" or "Chimps prefer to fish with their left hand"
Marginal asymmetry: "X chimps are right-handed for every Y left-handed chimps." [where X/Y
Let's be clear: handedness in humans is immensely asymmetric (9:1) at the population level, and holds across multiple tasks within individuals (most people are right-…
developingintelligence | October 17, 2007Cortical Column is a new blog by computational modeler and volleyball freak Brian Mingus - check out the interesting posts on "The Simulation Argument" and Deep Pressure Stimulation, which is argued to simulate deep brain stimulation of intralaminar thalamic nuclei - noninvasively!
developingintelligence | October 16, 2007Although most humans are right-handed, other animals don't seem to show a similar motoric asymmetry. As Corballis mentions in his 2003 BBS article, even the great apes - our closest relatives in the animal kingdom - tend not to show a right-hand preference unless raised in captivity, suggesting handedness is learned through imitation of caregivers. So why should humans be the only species to show clear manual asymmetry, 9:1 in favor of righties?
While manual asymmetry may be unique to humans, cerebral asymmetry is not. Corballis reviews how animals as diverse as frogs, birds, mice, rats,…
developingintelligence | October 3, 2007Ambiguity is a constant problem for any embodied cognitive agent with limited resources. Decisions need to be made, and their consequences understood, despite the probabilistic veil of uncertainty enveloping everything from sensory input to action execution. Clearly, there must be mechanisms for dealing with or resolving such ambiguity.
A nice sample domain for understanding ambiguity resolution is language, where problems of uncertainty have been long appreciated. The meaning of words in general (not to mention referents like "that" or "he") can be highly ambiguous (see "the gavagai…
developingintelligence | October 2, 2007Children are often thought to be imaginative and fanciful, not only in their perception of the world but also in the veridicality of their memories. It may therefore be surprising that a robust method for eliciting false memories in adults is actually ineffective in children. In fact, children even tend to show better performance than adults in terms of false recall in the DRM paradigm, a task in which a list of words must be remembered where every word in each list is strongly associated with a word that is not presented in each list. Adults tend to show a robust tendency to incorrectly…
developingintelligence | September 27, 2007Cognitive scientists are increasingly aware of how individual differences can confound experimental results. That is, differences in group means cannot always be interpreted clearly if, for example, only some subset of individuals in each group demonstrates the effect. Consequently, even the oldest paradigms in cognitive psychology are undergoing a revival with new mixed experimental/correlational methods.
Consider the Stroop effect, studied in detail since the 1930's, which is today understood as reflecting not merely the frequencies of color-word incongruity, but also a dynamic…
developingintelligence | September 26, 2007Infantile "amnesia" refers to the apparent absence or weakness of memories formed at ages younger than 3 or 4. Some evidence indicates that these early-life memories are not actually lost or forgotten, but are rather merely mislabeled or otherwise inaccessible to adult cognition. One potential reason for this inaccessibility is that adults tend to use language in encoding and retrieving memories, and this strategy may not be sufficient for retrieving memories formed in early-life, which may have been encoded before language is firmly entrenched in the developing brain. A recent study in…
developingintelligence | September 25, 2007Say you are writing an email when the phone rings. After the phone call, you return to finish the email. Are you slower to continue writing this email than you would be if you'd been doing something else prior to the phone call? In general, yes - at least according to the finding known as lag-2 repetition cost.
This idea has been tested in an experimental framework by having people perform three tasks (A, B and C) on the same set of stimuli. The critical question is whether you're slower to complete Task A if the previous trial order was A-B than if it was C-B. In general, you are slower…
developingintelligence | September 24, 2007What processes allow us to execute delayed intentions? This ability, known as prospective memory, is often considered to have two constituent parts: a prospective component which involves forming the intention and possibly maintaining it until action execution, and a retrospective component which involves retrieving this intention, if that intention is not successfully and continuously maintained until the moment of action execution.
These components can be easily illustrated. Imagine yourself in a situation where prospective memory is required: while at work, you realize that you need to…
developingintelligence | September 21, 2007The word "noise" comes from the latin nausea, meaning disgust or annoyance. But in the phenomenon known as stochastic resonance, noise can actually be a good thing: it can serve as a signal amplifier in thresholded systems.
This phenomenon is not nearly as arcane as it sounds. The image above (borrowed from Stein, Gossen & Jones, 2005), clearly shows how two very weak signals can look very similar (top row), but with additional noise, the characteristics of these signals can be more easily dissociated (bottom row; now you can see one signal is generated by a sine, and one generated by…
developingintelligence | September 20, 2007Can information be directed to different networks in the brain depending on the "transmission frequency", like the channels on a TV? A 2006 Cerebral Cortex paper reveals that this may not be as absurd as it sounds.
A relatively new technique in cognitive neuroscience is the use of frequency tagging, where a stimulus (whether visual or auditory) is presented at a certain rapid frequency, perhaps onsetting and offsetting six times per second (6Hz). A second stimulus may be presented at 4.5Hz. The frequencies can then be detected in the brain using magnetic or electric methods (MEG or EEG),…
developingintelligence | September 19, 2007In the "motion standstill" illusion, a rapidly moving object is perceived as motionless, and yet not blurred. This means that color, depth, and shape are accurately processed while the motion system fails: in fact, subjects are no better at detecting the direction of motion than chance.
At slightly different frequencies than those which elicit standstill, subjects can even be below chance at guessing the direction of motion, indicating motion aliasing (also observed in the wagon wheel illusion).
One hypothesis about the mechanism driving this illusion is that the temporal frequency of…
developingintelligence | September 14, 2007The claim that language processing can be carried out by purely "general purpose" information processing mechanisms in the brain - rather than relying on language-specific module(s) - may seem contradicted by a slew of recent neuroimaging studies demonstrating what appears to be a visual "word form" area in the left fusiform gyrus of the temporal lobe. By all appearances, this region is highly specialized for word processing. But this evidence causes a predicament for more than just domain-generalists; those who advocate an evolved language module may also be challenged by these results,…
developingintelligence | September 10, 2007An article in last week's Nature describes a highly experimental - but also highly promising - new treatment for patients who have undergone massive traumatic brain injury.
These patients are typically left in a "minimally conscious" state, showing little to no responsiveness to verbal commands, and little capacity to interact socially.
Schiff and colleagues identified one such patient who, despite having been in this state for nearly 4 years, nonetheless showed largely intact large-scale cerebral networks for processing language (as identified through functional neuroimaging). The authors…
developingintelligence | August 27, 2007In the Dimensional Change Card sorting (DCCS) task, 3-year-olds can usually sort cards successfully by a first rule - whether by shape, color, size, etc. When asked to switch then to another rule, most 3-year-olds will perseverate by continuing to sort cards according to the first and now-irrelevant rule. This occurs even when the current rule is repeated every single time they're asked to sort a card! Children will even correctly repeat the name of the rule they should be using, and then proceed to actually sort the card by the old rule.
By age 4, however, most kids are able to…
developingintelligence | August 24, 2007A long story short...
My PhD advisor, a developmental psychologist, recently had her first baby - unfortunately, this baby was born with the long-segment form of Hirschsprung's Disease. This means that Max has only 25 cm of ganglionated intestine; to survive he needs to mainline fatty acids a couple times per day. Such complete IV nutrition is typically supplied in the form of Omega-6's, which are massively damaging to the liver.
This means nearly every baby with a short-gut is soon on a liver transplant list. (Needless to say, this treats the symptom, not the cause; intestinal transplants…
developingintelligence | August 16, 2007Steve Grand, author of "Creation: Life and How to Make It" as well as a principal designer behind the groundbreaking artificial life game "Creatures", was recently interviewed over at MLU.
It covers a smattering of topics: recent proposals for a completely synthetic lifeform; analog computation; advantages of embodiment (not what you think!); animal intelligence and imagination; future directions in computational neuroscience.
developingintelligence | August 13, 2007What are the effects of prolonged boredom, for example as experienced by 17 months of interplanetary travel? This is the question investigated by a new European Space Agency project in which 12 volunteers will be locked in an isolation tank for 500 days. (In the comments, A.R. points out that this is probably bad reporting by the BBC, as the project actually seems to involve an isolated living space rather than a true isolation tank).
An "isolation tank" is a dark, soundproof container of salt water heated to skin temperature which is intended to induce sensory deprivation - an absence of…
developingintelligence | August 7, 2007Having just returned from a 3 week vacation to purchase (and then move into) a new home, I am finally now able to get back to posting. Here's just a very small subset of the best in brain-blogging while I was away:
Fundamental limitations in predicting individual differences: the margin of error in predictive algorithms of individual behavior (as used, for example, by the UK Department of Health to determine whether an individual is fit for release from a psychiatric institution, and much more widely in marketing and finance) may be so high as to render some of these algorithms unusable.…