From: m.usher@psychology.bbk.ac.uk
Date: Fri Feb 02 2001 - 08:06:40 MST
The following article, to appear in PSYCHOLOGICAL REVIEW, can be now
accessed in electronic format from the following web-sites:
www.psyc.bbk.ac.uk/staff/mu/homepage/LCAC/LCAM.ps.gz (gunziped postscript)
www.psyc.bbk.ac.uk/staff/mu/homepage/LCAC/LCAM.pdf (pdf-file)
The article may be relevant to people that are interested in the
use of simple neural mechanisms (in particular neural decay,
recurrent excitation and lateral inhibition) for developing models of
choice and response latency that approximate stochastic diffusion or
random-walk models often used to generate response time distributions
in choice tasks. The article also shows how the model is fit to behavioral
data and how one can optimize the model parameters to account for
individual patterns of behavior.
On the Time Course of Perceptual Choice:
The Leaky Competing Accumulator Model
Marius Usher James L. McClelland
Department of Psychology Carnegie Mellon University and the
Birkbeck College Center for the Neural Basis of Cognition
E-mail: m.usher@bbk.ac.uk E-mail: mcclelland+@cmu.edu
Abstract
The time course of perceptual choice is discussed in a model
based on gradual and stochastic accumulation of information in
non-linear decision units with leakage (or decay of activation) and
competition through lateral inhibition. In special cases, the model
becomes equivalent to a classical diffusion process, but leakage and
mutual inhibition work together to address several challenges to
existing diffusion, random-walk, and accumulator models. The model
provides a good account of data from choice tasks using both
time-controlled (e.g., deadline or response signal) and standard
reaction time paradigms and its overall adequacy compares favorably
with that of other approaches. An experimental paradigm that
explicitly controls the timing of information supporting different
choice alternatives provides further support. The model captures
flexible choice behavior regardless of the number of alternatives,
accounting for the linear slowing of reaction time as a function of
the log of the number of alternatives (Hick's law) and explains a
complex pattern of visual and contextual priming effects in visual
word identification.
M. Usher
Reader in Psychology
Birkbeck College, Univ. of London
Tel: 44-207-631 6201
FAX: 44-207-631 6312
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