Two groups of cats were trained to make a visual discrimination between two patterns in a standard discrimination apparatus. Animals in Group I were trained until they reached a criterion level of 90% correct responding, had bilateral lesions made in the superior colliculi (SC), and were retrained. Animals in Group II had bilateral lesions made in the SC and were then trained on the visual discrimination task. While all animals in Group I relearned the discrimination to criterion in 60 trials or less, animals in Group II either failed to learn the problem or required more than 380 trials to reach criterion.