Fall 2001

Tuesdays 12:15  Goldwater 604

(Supported in part by the Systems Science and Engineering Research Center)

Seminar Schedule: <http://math.la.asu.edu/~tom/cognition/math+cogsched.html>

Our next meeting of the Mathematics and Cognition seminar will take place on
Tuesday, September 25, at 12:15 PM in GWC 604.    Our speaker will be Professor
Dr. Peter Killeen of the Department of Psychology, who will speak on the topic:

"Pavlov vs. Skinner: Sudden Death on the Nile"

Abstract.
Hungry pigeons were fed periodically, with food always signaled by the onset of a
key light. Measured responses to thekey aborted the scheduled feeding. Response
probability remained above zero for most subjects, inconsistent with Skinnerian
conditioning. A simple model of Pavlovian conditioning was ruled out by the data
of 7 of 8 subjects, which provided evidence for persistence in the behavior of pecking
or non-pecking. Hazard functions seemed to support the persistence model, but were
invalidated by a drift in baserates. Two methods for isolating changes in probabilities
from base probabilities converged on an estimate of 0.5 to 2% increase in probabilities
of a peck after a trial with a peck,and a quiet after a trial with a quiet. A statistical technique
originating in the study of watersheds by Abu Nil, the rescaled range analyses, verified
the tendency for pecking and non-pecking to persist. The analysis provided an index of
that persistence, the Hurst exponent H, that covaried with the other measures of persistence.
The measured values of H ruled out Markov models, and provided some evidence for a
basic model of persistence modulated by learning.