| Abstract: | Proactive inhibition in the pigeon was studied using a delayed-color-matching-to-sample task, with and without presentation of stimuli prior to the sample. Interference theory predicts that, relative to control performance, the disruptive effects of a prior stimulus should increase over a retention interval, while decay theory predicts that such disruptive effects should decrease over time. Results supported decay theory when performance was at a low level and interference theory when performance was at a high level. With performance at an intermediate level, parallel functions were obtained, an outcome supporting neither theory. It was concluded that the results supporting interference and decay theories were artifactually produced by floor and ceilling effects, respectively, and it was suggested that the results of earlier experiments using the present paradigm may well have been influenced by similar artifacts. Inserting a nondisruptive stimulus between a prior disruptive stimulus and the sample virtually eliminated the disruptive effects of the prior stimulus when tested immediately, but not when tested after 1 sec. The results of the present experiments and related findings can best be explained by either a modified decay theory (Grant, D. S. Proactive interference in pigeon short-term memory. Journal of Experimental Psychology: Animal Behavior Processes 1975, 104, 207–220) or a modified temporal discrimination theory. |
