Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Dr. M. Kay Malott

Second Advisor

Dr. Jack Michael

Third Advisor

Dr. Art Snapper


Prior studies found that separations between latencies correlated with differential stimuli in a multiple discrete trial procedure were attenuated with increased intertrial interval durations. In this study six pigeons served as subjects in two groups. The procedure for one group was a multiple DRO-FR chain schedule (Ratio Delay group) while in the other group a multiple DRO - response-initiated delay interval chain schedule (Time Delay group) was used. Results of this study are consistent with the Delay-reduction hypothesis of evocative effectiveness which predicts that with increasing initial link durations relative terminal link evocative effectiveness would decrease. Specifically, relative terminal link latency varied as a function of initial link durations as predicted by the Delay-reduction hypothesis. However, relative terminal link running rates varied as a function of initial link durations, as predicted, for only two subjects, both of the Time Delay group. Failure of the Ratio Delay terminal link running rates to vary as predicted are explained by the possible increased differential reinforcement of short interresponse times afforded by the longer terminal link FR. Implications discussed include the misuse of discrete trial terminology and the application of the Delay-reduction hypothesis to the analysis of behavioral contrast.

Access Setting

Dissertation-Open Access