Effects of prior and interpolated learning on retention in pigeons.

Abstract

A discrimination situation was developed for pigeons which would permit the investigation of retention problems in the animal laboratory. Changes in Retroactive and Proactive Inhibition (RI and PI) were studied as a function of the length of the retention interval (1, 10, or 30 days). A 5-key discrete-trial situation was employed in which a task was defined by the key color that was associated with reinforcement. Comparison of the number of correct responses made by the various groups on Day 1 of relearning permits the following conclusions (a) Retroactive Inhibition was very prominent at all retention intervals. (b) The RI Ss relearning after a 30-day interval performed better than those relearning after a 1- or 10-day interval. (c) Ss learning and additional task prior to the task to be recalled made as many correct responses during the retention test as did control Ss. That is, no Proactive Inhibition was evident. (d) Both PI and control Ss relearning after a 30-day interval performed more poorly at recall than did those Ss relearning after a 1- or 10-day interval[long dash]a trend opposite to that shown by the Ss in the RI condition. A supplementary experiment showed that even when the number of prior tasks was increased from 1 to 2, no PI was evident after a 30-day interval[long dash]the only interval tested under this special interference condition.