Control of Response Initiation:
Mechanisms of Adaptation to Recent Experience
Michael C. Mozer, Sachiko Kinoshita, and Colin Davis
In most cognitive and motor tasks, speed-accuracy trade offs are
observed:
Individuals can respond slowly and accurately, or quickly yet be prone
to
errors. What sort of control mechanism governs the initiation of a
behavioral
response? A strong source of constraint on a theory of control comes
from
the finding that response time and accuracy depend on the recent
stimulus
environment: when stimuli can be characterize on an easy-hard dimension
(e.g., word frequency in a naming task), an easy item is responded to
more
slowly when intermixed with hard items than when presented among other
easy
items; likewise, hard items are responded to more quickly when
intermixed
with easy items. We propose a computational theory with three
components:
a model of temporal dynamics of information processing, a decision
criterion
specifying when a response should be initiated, and a mechanism of
adaptation
to the stimulus environment. Performance during the course of an
experimental
trial is cast in terms of a utility function that increases with
accuracy and
decreases with response time. We assume a decision criterion that
initiates
a response at the point in time that maximizes expected utility. We
posit
that the blocking effect arises because information concerning recent
trial
difficulty is incorporated into the utility estimate. We present
further
behavioral studies to validate predictions of the theory.
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