| Abstract: | The retention performance of independent groups of rats was examined at various intervals following one-trial passive avoidance training. Performance was good in the 30-sec, 15-min, 12-hr, 24-hr, and 36-hr group, while retention was significantly poorer between these peaks. Control experiments appear to rule out strictly performance factors related to footshock. These results suggest that some rhythmic internal (physiological) state of the organism may be a relevant condition for optimal retrieval—a state-dependent hypothesis. |
