Home > Events > CogSci Colloqium: Randy Gallistel (Rutgers)

CogSci Colloqium: Randy Gallistel (Rutgers)

Time: 
Thursday, February 08, 2018 - 3:30 PM to 6:30 PM
Location: 
BPS 1208

Title: The Perception of Probability

Abstract: Human and non-human animals estimate the probabilities of events spread out in time. They do so on the basis of a record in memory of the sequence of events, not by the event-by-event updating of the estimate. The current estimate of the probability is the byproduct of the construction of a hierarchical stochastic model for the event sequence. The model enables efficient encoding of the sequence (minimizing memory demands) and it enables nearly optimal prediction (The Minimum Description Length Principle). The estimates are generally close to those of an ideal observer over the full range of probabilities. Changes are quickly detected. Human subjects, at least, have second thoughts about their most recently detected change, revising their opinion in the light of subsequent data, thereby retroactively correcting for the effects of garden path sequences on their model. Their detection of changes is affected by their estimate of the probability of such changes, as it should be. Thus, a sophisticated mechanism for the perception of probability joins the mechanisms for the perception of other abstractions, such as duration, distance, direction, and numerosity, as a foundational and evolutionarily ancient brain mechanism.

Bio: Charles Randy Gallistel is a Professor in the Center for Cognitive Science at Rutgers University. His research pursues a psychophysical approach to screening for memory malfunction in genetically manipulated mice. The purpose is to make possible a genetic attack on the problem of the physical (cellular and molecular) basis of memory by developing behavioral screening methods that distinguish between genetic defects in memory per se and genetic defects in the many processes that affect the extent and manner in which memory is manifest in behavior. Memory is the mechanism or mechanisms that carry information forward in time within nervous systems. His behavioral screens look for distortions and increased noise in simple quantitative memories like interval duration, distance and number. It is psychophysical in character in that it tests memory for the same simple quantity repeatedly (hundreds of times) and processes the results with the kind of elaborate statistical analysis employed in psychophysical work on sensory systems. As in sensory psychophysics, the goal is to extract from behavioral data quantitative properties of the underlying mechanisms. The experimental research grows out of my theoretical research on problem-specific (modular) information processing approaches to learning and memory.