developingintelligence | May 30, 2007While the "modal model of memory" is still widely taught and accepted as a general theory, an enormous amount of recent research has focused on how short-term memory enables higher cognitive processes like those involved in planning, goals, and executive functions. Yet this research has revealed surprisingly intricate links between short- and long-term memory. Increasingly, it appears that interactions among prefrontal areas (traditionally thought to be important for short-term memory) and medial temporal lobe areas (traditionally thought to be important for long-term memory) are important…
developingintelligence | May 29, 2007The capacity to use and manipulate symbols has been heralded as a uniquely human capacity (although we know at least a few cases where that seems untrue). The cognitive processes involved in symbol use have proven difficult to understand, perhaps because reductionist scientific methods seem to decompose this rich domain into a variety of smaller components, none of which seems to capture the most important or abstract characteristics of symbol use (as discussed previously).
So, it's important to specify how the simpler and better-understood aspects of symbol processing may interact and give…
developingintelligence | May 25, 2007Highlights from recent brain blogging:
First, a new edition of Encephalon.
Physicalism and Panpsychism - a book review by Jerry Fodor. Looks like a pretty nice book...
And here, Fodor explains mental representation to his aunt.
Silicon smackdown - an article in the June Scientific American talks about new algorithms for playing the ancient board game Go, one of the last quantitative arenas where humans are clearly superior to machines. Subscription only, sorry guys.
Whistle, Bark and Groan - with a dolphin accent?
Thinking Meat comments on a NYT article on the social construction of reality…
developingintelligence | May 24, 2007Many will agree that algebra is difficult to learn - it involves planning, problem-solving, the manipulation of symbols, and the application of abstract rules. Although it's tempting to imagine a specialized region of the brain for each of these processes, they may actually recruit roughly the same widely-distributed and general-purpose "task network" of brain regions. The individual contribution of each region has been, and continues to be, a matter of much debate.
However, the functional specialization of each brain region may be best understood as fulfilling a particular balance between…
developingintelligence | May 18, 2007Recent highlights from the best in brain blogging:
Who knew? These videos will tell you how the mind works (supposedly).
The origins of the old myth that we use only 10% of our "brain power".
A woman awakens from a coma with a reversed sense of directionality.
Restoring sight in the blind with lateral geniculate nucleus implants
"Do you, for some reason, fear the current and/or future increase of artificial intelligence?"
Questions about the utility of computational neuroscience
From Molecule to Mind: The Genetics of Brain Wiring
Dostoyevsky's case of epilepsy: "I gazed at him with fixed…
developingintelligence | May 17, 2007Prospective memory is "remembering to remember." Despite the pervasiveness of this requirement in real-life, we know surprisingly little about the topic. In their new book, McDaniel & Einstein provide a direly needed review of this fascinating new field, providing important information for researchers, clinicians, and laypeople alike on how basic cognitive science is coming to a "big picture" understanding of prospective memory.
In some ways, it's not so much a single topic as an amalgam of many different cognitive processes already studied in other domains. For example, prospective…
developingintelligence | May 16, 2007The analytic depth of cognitive neuroscience is, in many ways, a curse. Those aspects of high-level cognition most relevant to real-world applications are the least understood at a neurobiological level, and those mechanisms that are well-understood neurobiologically are too simple to inform real-world practices.
The explanatory gaps between these levels of analysis is a result of hyper-reductionism in science, itself rooted in a lasting preference (reverence?) for the simplistic and "parsimonious." But natural phenomena, like the emergence of behavior from the brain, are ultimately more…
developingintelligence | May 15, 2007It could be argued that any single level of scientific analysis is at once too simple (since there are always important emergent phenomena at higher levels) and also too complex (poorly-understood phenomena inevitably lurk at lower levels). If I wanted to kick the sacred cow of science again, as I did yesterday, I'd suggest that parsimony can be a misleading principle here too: whatever data is used to evaluate a theory may not include phenomena occurring at other levels of analysis that may be relevant to the theory. So inevitably, the simplest theory (i.e., the one with the fewest…
developingintelligence | May 14, 2007Theories with the fewest assumptions are often preferred to those positing more, a heuristic often called "Occam's razor." This kind of argument has been used on both sides of the creationism vs. evolution debate (is natural selection or divine creation the more parsimonious theory?) and in at least one reductio ad absurdum argument against religion. Simple theories have many advantages: they are often falsifiable or motivate various predictions, and can be easily communicated as well as widely understood.
But there are numerous reasons to suspect that this simple "theory of theories" is…
developingintelligence | May 9, 2007"Where is it, this present? It has melted in our grasp, fled ere we could touch it, gone in the instant of becoming." - William James, 1890
Extremely dangerous, traumatic, or surprising moments are often accompanied by reports that time seemed to "slow down" or "fly by." The perceptual basis of these subjective temporal distortions is unclear, but not for lack of trying: one recent experiment went so far as to drop subjects off a 400 foot tower while testing their ability to decipher a rapidly flashing string of numbers - a test of perceptual processing speed. Unfortunately, it didn't work…
developingintelligence | May 7, 2007Hemispatial neglect might be the most striking example of brain trauma's cognitive effects: patients with damage to right parietal regions appear unaware of the left half of space. For example, they'll often shave only the right side of their face, will only eat food from the right half of their plate, and when asked to copy a variety of drawings will include only their right half.
As you can tell from these examples, right parietal cortex is particularly important for our understanding of space. Although left parietal cortex may be involved in similar computations, the right-sided region…
developingintelligence | May 3, 2007In his famous essay, Thomas Nagel suggested that science's reductionist methods can never provide a complete understanding of the "subjective qualities" of consciousness. To illustrate this problem, he wrote that there was "no reason to suppose that" we would ever be able to comprehend what it's like to be a bat - because we can't truly understand the subjective experience of, for example, echolocation.
Ironically, scientific advances in "sensory substitution" technology have demonstrated that it's possible to simulate (or stimulate) one modality (sight, hearing, touch) with sensory data…
developingintelligence | May 2, 2007What neural mechanisms underlie "fluid intelligence," the ability to reason and solve novel problems? This is the question addressed by Gray et al. in Nature Neuroscience. The authors begin by suggesting that fluid intelligence (aka, gF) is related to both attentional control and active maintenance of information in the face of ongoing processing (i.e., working memory). Each of these concepts, in turn, has been associated with the functioning of the lateral prefrontal cortex - a region that has been massively expanded in humans compared to even our closest evolutionary relatives.
To…
developingintelligence | April 27, 2007Early neuropsychology research indicated that long-term memory and short-term memory were separable - in other words, long-term memory could be impaired by damage to the hippocampus without any corresponding deficits in short-term memory. However, this idea has come under scrutiny in recent years. Neuroimaging technology has demonstrated that the same network of brain regions is active in both long-term and short-term memory tasks, suggesting that these regions may interact more than previously assumed. As noted in Speer, Jacoby & Braver's 2003 article, estimates of either type of…
developingintelligence | April 26, 2007People are remarkably bad at switching tasks - and research focusing on this fact has isolated a network of brain regions that are involved in task-switching (I'll call it the "frontal task network" for short). One of the stranger findings to emerge from this literature is the fact that we're actually worse at switching to a more natural or well-practiced task after having performed a less natural one.
One potential explanation for this "switch cost asymmetry" is that the task network may recognize the potential for errors when performing the unnatural task, and therefore "help it along"…
developingintelligence | April 25, 2007A lack of clear definitions for terms like "intelligence" and "consciousness" plagues any serious discussion of those concepts. A recent article by Seth, Baars & Edelman argues for a core set of 17 properties that are characteristic of consciousness, and could be used in the "diagnosis" of consciousness in humans and other animals.
Property 1: "Irregular" patterns of brain activity
Electrical oscillations occuring between 20 and 70 times per second are common in awake humans, but epilepsy, sleep, anesthesia and some forms of brain damage are accompanied by the dominance of highly regular…
developingintelligence | April 24, 2007Ever heard that "you're born with all the brain cells you'll ever have"? It turns out that could be a good thing - if it were true. A new study shows that at least in some circumstances, neurogenesis actually impairs memory performance.
To understand why this might be the case, consider that adults are constantly generating new neurons in a long-term memory structure - the hippocampus. This region requires a large number of neurons to store episodic memories accumulated over a lifetime (and understandably so!). Similarly, to be able to store experiences that may have occurred very…
developingintelligence | April 20, 2007Have you ever momentarily forgotten the name of a specific place, or person, despite being able to recall many things about the name (for example the first few letters, or the number of syllables)? Chances are, if you've experienced this "tip-of-the-tongue" phenomenon, you've also had the word spontaneously occur to you minutes or hours later. One explanation for this fascinating failure of memory is retrieval-induced forgetting, in which the retrieval of closely related concepts and words actually competes with the word or concept you intended to retrieve (discussed previously). The…
developingintelligence | April 19, 2007Children are famously bad at considering the future consequences of their actions, but some evidence suggests this criticism is slightly off-the-mark: they may not even comprehend "time" in the same way adults do. A variety of findings from multiple lines of research tentatively support this surprising claim about the limitations of children's cognition.
Based on the delay of gratification literature, we know that children will reliably choose "less now" rather than "more later" - even at relatively short delays. Children may not be able to adequately represent the value of a future reward…
developingintelligence | April 18, 2007What better way to start out than some cool visual illusions known as hybrid images.
It's a short jump from visual illusions to mass delusions.
Is the benefit of exercise a similar mass delusion, a kind of population-level placebo effect?
How do we turn perception into action? It may involve binding between the brain's dorsal and ventral visual processing streams.
A new NSF-funded center for understanding the temporal dynamics of learning.
The mystery of sleep, at Slate.
Propranolol, the amnesia drug: one step closer to eternal sunshine.
Nicotine as a memory (and attention) enhancer? Don't…