Odum, A. L., Shahan, T. A, & Nevin, J. A. (2005).
Resistance to change of forgetting functions and response rates.
Journal of the Experimental Analysis of Behavior, 84, 65-75.
This experiment examined the effects of reinforcement probability on resistance
to change of remembering and response rate. Pigeons responded on a two-
component multiple schedule in which completion of a variable-interval 20-s
schedule produced delayed matching-to-sample trials in both components. Each
session included four delays (0.1 s, 2 s, 4 s, and 8 s) between sample
termination and presentation of comparison stimuli in both components. The two
components differed in the probability of reinforcement arranged for correct
matches (i.e., rich, p = .9; lean, p = .1). Response rates during the variable-
interval portion of the procedure were higher in the rich component during
baseline and more resistant to the disruptive effects of intercomponent food and
extinction. Forgetting functions were constructed by examining matching accuracy
as a function of delay duration. Baseline accuracy was higher in the rich
component than in the lean component as measured by differences in the y-
intercept of the forgetting functions (i.e., initial discrimination), rather
than from differences in the slope of the forgetting function (i.e., rate of
forgetting). Intercomponent food increased the rate of forgetting relatively
more in the lean component than in the rich component, but initial
discrimination was not systematically affected. Extinction reduced initial
discrimination relatively more in the lean component than in the rich component,
but did not systematically affect rate of forgetting. These results are
consistent with our previous data suggesting that, as for response rate,
accuracy and resistance to change of discriminating are positively related to
rate of reinforcement. These data also suggest that the disruptability of
remembering depends on the conditions of reinforcement, but the way in which
remembering is disrupted depends on the nature of the disruptor.
Key words: delayed matching to sample, forgetting functions, reinforcer
probability, resistance to change, key peck, pigeons