See
erratum, July 2004, 82, 20.
Sargisson, R. J., & White, K. G. (2003).
The effect of reinforcer delays on the form of the forgetting function.
Journal of the Experimental Analysis of Behavior,
80, 77-94.
Pigeons were trained in a matching-to-sample procedure with
retention intervals of 0, 2, 4, 6, and 8 s mixed within each
session. In different conditions, reinforcement was delayed by 0,
1, 2, 4, 6, or 8 s from correct choice responses.
Discriminability decreased with increasing retention-interval
duration and with increasing reinforcer delay. Exponential
forgetting functions were fitted to discriminability measures
plotted as a function of retention interval. Initial
discriminability (intercept of the fitted functions) decreased
with increasing reinforcer delay. Rate of forgetting (slope of
the fitted functions) increased with reinforcer delay, suggesting
an interaction between the effects of reinforcer delay and
retention interval. The data were well described by multiplying
an exponential function describing the effects of retention
interval by a hyperbolic function describing the effect of
reinforcer delay. This description included an interaction term
that allowed for a greater effect of reinforcer delay at longer
retention intervals.
Key words: forgetting functions, reinforcer delay, retention
interval, delayed matching-to-sample, pigeon