Age differences in aversively motivated visual discrimination learning and retention in male Sprague-Dawley rats

Rats 3, 7, 12, and 24.5 mo. old were trained to an 11/12 correct initial response criterion on a shock-motivated light-dark discrimination. Eight days later they were retrained to the same criterion. Original learning and relearning rates were not correlated, but both decreased linearly with increasing age. Ray and Barrett (1973) recently reported that, while year-old rats made fewer avoidances than younger animals on a shock-motivated discrimination, they appeared to have learned equally well, since there were no differences in number of correct initial responses. They suggested that avoidance scores may reflect performance factors and that learning decrements with age might not occur if the correct initial response measure were used. The present study demonstrates that this is not the case; when rats as old as 24.5 mo. are tested there are clear age-related deficits in number of correct initial responses.