Visual discrimination of flux-equated figures by cats with brain lesions.

Cats with various brain lesions were compared in their abilities to learn or relearn for food reward to a strict performance criterion a simple dark--light discrimination and 3 sets of discriminations between pairs of triangle equated for overall luminous flux. The results revealed a spectrum of deficits in visual learning by cats with different lesions and indicate: (1) cats with bilateral lesions of the superior colliculus-pretectum can learn dark-light and geometric figure discriminations in approximately the same number of training trials as unoperated cats or as cats with bilateral lesions of the lateral-posterolateral and splenial gyri; (2) cats with bilateral lesions of the superior colliculus-pretectum can learn to discriminate from a distance between geometric figures equated for overall luminous flux; (3) cats with bilateral lesions of the suprasylvian and ectosylvian gyri in addition to the lateral-posterolateral and splenial gyri require more training to learn both types of visual discriminations than unoperated cats or cats with lesions either of the superior colliculus-pretectum or of the lateral-posterolateral and splenial gyri; (4) cats require either an intact superior colliculus-pretectum or intact lateral-posterolateral and splenial gyri in order to discriminate between geometric figures; (5) cats with bilateral lesions of the posterior two-thirds--three-fourths of the neocortex and most of the superior colliculus-pretectum can learn a simple dark-light discrimination after prolonged training.