Developmental Psychology
developingintelligence | April 17, 2007Your body's bilateral symmetry statistically predicts your health, probability of schizotypy and depression, number of sexual partners, and resting metabolic rate (particularly if you are male). Bodily symmetry may reflect "developmental stability" - i.e., influences like disease, mutation and stress may cause a developmental divergence from DNA's symmetric blueprint. Not only do individuals differ in their environmental exposure to these things, but also in their sensitivity to them: a recent Intelligence article claims that "some individuals grow adaptive phenotypes under almost any…
developingintelligence | April 4, 2007"Instead of trying to produce a programme to simulate the adult mind, why not rather try to produce one which simulates the child's?" - Alan Turing (Computing Machinery, p456)
One of the defining features of childhood cognition is "behaving without thinking." Not surprisingly, developmental cognitive psychology has latched onto the idea of impulse control - and other processes putatively requiring inhibition - as a central explanatory construct, playing a role in attention deficit disorder, post-traumatic stress disorder and everything in between (including developmental trends in normal…
developingintelligence | March 23, 2007The past continuously besets our ability to act flexibly in the future; habits grow strong, automaticity takes over and the mind wanders. Before you know it, you've forgotten to stop for milk on your regular commute, neglected to go to your dentist appointment, or merely "lost track" of what you were doing. These kinds of things are often studied in cognitive control laboratories, usually in the context of a task where there is particularly strong "proactive interference" from previous habits (for example, the habit to read color-words instead of naming ink-colors in the Stroop task).
A…
developingintelligence | March 7, 2007According to artificial neural network models that implement lateral inhibition, activation and inhibition are two sides of the same coin. These models often assume that patterns of activation compete with one another. In other words, in a given space of neural tissue (or "layer" in network terms), some particular pattern will become most active. This pattern will effectively suppress the emergence of other patterns through lateral inhibition; other patterns are less likely to emerge if the current dominant pattern is very strongly represented.
This assumption of "competition for…
developingintelligence | March 1, 2007Cognitive theories of "executive function" vary greatly in the number of distinct cognitive processes they propose to subserve the goal-directed coordination of behavior. Some theories suggest that strong active maintenance of information, and a way of "updating" the information that is maintained, is sufficient to explain performance on executive function (EF) tasks, which typically require careful control over behavior. Other theories propose that a process of "inhibition," distinct from updating and maintenance, must also exist. And then there are those theories that propose yet other…
developingintelligence | February 22, 2007Children are famously bad at remembering to do things - for example, taking out the trash. What exactly is the developmental trajectory of the ability to remember and execute planned actions (known as prospective memory)? Although the effects of traumatic brain injury and old age on prospective memory are becoming elucidated, we have little idea how prospective memory comes to function in the first place. This is the topic covered by Kliegel & Jager's 2007 article in Cognitive Development.
Previous had suggested that even 2-year-olds might have some capacity for prospective memory,…
developingintelligence | February 21, 2007Findings in the laboratory do not always apply to the real-world - a myriad of factors can influence real-world phenomena, and scientists actively seek to eliminate many of them in their laboratories. But ecological validity can be particularly difficult to establish in cognitive science, where real-world levels of motivation, stress, and memory load can not always be practically (or ethically) simulated in the laboratory.
Ecological validity may be particularly important in tests of prospective memory - the ability to remember to perform a planned future action. One salient example: young…
developingintelligence | February 20, 2007In the middle of the work day, you realize you'll need to stop at a store on your way home from work. Your ability to actually do so, hours later, relies on what some psychologists call "prospective memory." Although prospective memory is clearly important for human intelligence, very little is known about how it works.
Clearly there are at least two kinds of prospective memory. In the example above, you may tell yourself "stop at the store" again and again until you pull into the store's parking lot - this is known as a vigilance or monitoring strategy. Or the store may simply catch your…
developingintelligence | February 1, 2007Yesterday I reviewed evidence showing that set switching (e.g., your ability to suddenly switch behaviors) and rule representation (your ability to represent rules in a game, for example), may be distinct processes, at least insofar as they may show distinct developmental trajectories and rely on distinct neural substrates. Today's post will review a new study from Developmental Neuropsychology that also aims to show distinct developmental trajectories for set switching and rule maintenance, and how these claims hold up to a deeper analysis.
Huizinga & van der Molen administered four…
developingintelligence | January 31, 2007Normal children - and adult patients with frontal damage - frequently have difficulty changing their responses to stimuli when the correct response changes. This difficulty is often considered an inability to switch between rules, but might result not so much from an inability to switch as from an inability to represent the stimuli as having two possible responses in the first place (i.e., to represent the stimuli as "bivalent"). Supporting this distinction is a new article in the Journal of Neuroscience that claims to distinguish the networks supporting "bivalent" representation from those…
developingintelligence | January 29, 2007If presented with a novel and a familiar object, infants strongly prefer to touch and look at novel objects. However, if these objects are then obscured - in the dark, or by an occluding screen - infants tend to reach more in the direction of the familiar objects. Some argue that the familiar objects are represented more strongly by neural networks, whereas the relatively weaker representations of novel objects are more likely to decay in the absence of sensory input, and thus less likely to motivate an infant's reach.
Similar mechanisms may exist in adults. A review of the literature…
developingintelligence | January 19, 2007Although even the youngest infants have some ability to remember the past, this ability increases in both its reliability and its "temporal extent" with age. Such differences could result from changes in any of memory's constituent processes, including encoding, consolidation, or retrieval. Although this week's posts have focused on the idea that source monitoring difficulties underlie the apparent loss of early memories (i.e., a difficulty in retrieval), Bauer's 2006 TICS review emphasizes emerging evidence that encoding and storage or consolidation are also to blame.
Bauer has argued that…
developingintelligence | January 18, 2007The media is currently blowing up with reports that a 27-year-old woman who disappeared in the forests of Cambodia has now been found, 18-20 years later (reports vary). She was spotted on January 13th by a villager who saw a "jungle person, sneaking in to steal his rice," and was subsequentely identified as Rochom P'ngieng by a scar on her arm.
Reports suggest that she does not speak the local language, although she does communicate with gestures: she pats her stomach to indicate she is hungry.
Her father said that she initially resisted the wearing of clothes and use of chopsticks, and…
developingintelligence | January 18, 2007Yesterday I outlined a few reasons to think that we may not actually forget all of our earliest memories; instead, they may merely be mislabeled due to a failure of source monitoring. According to a 2002 article by Drummey and Newcombe, a similar problem may underlie childhood amnesia - the fragmentary nature of autobiographical memory prior to age 6.
Failures of source monitoring are more frequent in patients with brain damage to the frontal cortex (and may be especially reliant on the right frontal lobe). Just like these frontal patients, preschool-aged children have a prefrontal cortex…
developingintelligence | January 17, 2007Freud famously suggested that infantile amnesia is an active suppression of early traumatic memories. However, a review of the modern cognitive literature suggests that at least in some ways, infantile amnesia may actually be a myth.
Perhaps the most intuitive explanation of infantile amnesia is simply that the infant's brain is not sufficiently developed to support episodic memory. However, substantial evidence argues against this view. For example, the same factors that affect episodic memory in adults also affect infant memory, including age, retention interval, context change,…
developingintelligence | January 16, 2007Suppose that "memory task A" shows marked improvement at 5 months, but "memory task B" doesn't show marked improvement until 9 months. Before we can make inferences about the development of memory, we need to understand how tasks A and B differentially strain the developing cognitive system.
Along these lines, Gross et al.'s 2002 Developmental Psychobiology article investigates the relationship of three different memory tasks in 6-month-old infants. The tasks are pretty representative of current behavioral work with human infants:
1) In the mobile conjugate reinforcement paradigm, infants…
developingintelligence | January 4, 2007There are many theories of how human behavior came to differ so profoundly from that of even our closest primate relatives - language, recursion, theory of mind, and enhanced working memory are just a few of the "critical components" that have been proposed as enabling human intelligence. A very different perspective, advocated by Tomasello and Carpenter, suggests that it is simply humans' extreme propensity for social interaction that is at the core of the evolution of human intelligence.
In their article, Tomasello and Carpenter focus on four effects of this social tendency, which they…
developingintelligence | January 3, 2007The prefrontal cortex is a major recipient of subcortical dopaminergic projections. Accordingly, almost all of the behavioral tasks that are known to critically depend on the prefrontal cortex are sensitive to dopamine levels. A curious exception is the Self Ordered Pointing task (SOPT), in which subjects must select each of 9 designs by pointing at each one once; after each selection, the locations of the designs are randomized. Therefore, in order to succeed at this task subjects must remember the designs themselves and not the locations to which they pointed.
The dorsolateral…
developingintelligence | January 2, 2007It seem reasonable that evolution might select for adaptive behaviors by increasing the relative size of particular brain regions that support those behaviors; for example, bats might have an enlarged auditory cortex since they navigate with echolocation. To some extent this does happen, but such differences are often apparent only after controlling for a much larger source of variance: changes in brain size that correlate with changes in body size - and the implications of this fact are wide-reaching.
As Barbara Finlay and coauthors wrote in this 2001 Behavioral and Brain Sciences article,…