Abstract
Spatial discrimination reversal learning was explored for mice genetically selected for high brain weight and unselected controls with lower brain weights. Control-line Ss escaped from a water maze more rapidly, but high-line Ss made fewer errors and took less trials to reach criterion on the first reversal. Control-line Ss were unable to complete more than 1 reversal, while high-line Ss all completed at least 7 reversals. This positive relation between reversal learning and brain size is consistent with comparisons among species and experiments manipulating brain size by means of drugs or surgery.