The effects of retroactive and proactive interference on learning and memory in old and young rats.

The effects of interference on learning and memory in old and young rats were compared using a visual discrimination task. In Experiment I, discrimination training was followed by one of three interference treatments and finally by retesting on the discrimination task. There were no age differences in original learning but old rats were significantly impaired in remembering the visual discrimination when a high-interference treatment involving similar stimuli was introduced between original learning and retesting. In Experiment II, old rats were impaired on discrimination learning when the high-interference treatment was administered before discrimination training. Analysis of response patterns showed that the exaggerated susceptibility of old rats to interference effects resulted in a general behavioral inflexibility similar to that observed in young adult rats with damage to the hippocampal region.