Monkeys with thermocoagulation or kainic acid lesions of the pulvinar and unoperated control monkeys were tested in two tasks: pattern discrimination retention and color discrimination learning in which the stimuli were located at the response sites or were separated spatially from them (S-R separation). The monkeys with kainic acid pulvinar lesions were mildly impaired in retention of the pattern discrimination, but were unimpaired in the color discrimination tasks with or without the S-R separation. The monkeys with thermocoagulation lesions, like monkeys with superior colliculus lesions in a prior study, were severely impaired in performing one of the color discrimination tasks with S-R separation. These findings suggest that: (a) the inferior pulvinar, unlike the superior colliculus, does not contribute to the performance of discriminations involving S-R separation; and (b) corticotectal projections traversing the pulvinar and destroyed by the thermocoagulation lesions are crucial to the performance of discriminations involving S-R separation. The results of an earlier experiment also suggested that interruption of corticotectal fibers passing through the pulvinar impairs performance in another task sensitive to superior colliculus lesions--spatial localization of light flashes. Thus, corticotectal projections may be crucial for the contribution of the colliculus to performance in a variety of visual tasks.