Monkeys with lesions of the frontal granular cortex showed severe impairment of learning ability on problems requiring right-left alternation, up-down alternation or "go, no-go" respond or not respond type of response to a single stimulus object. Correct responses in the latter problem rose to above-chance levels, but only after a longer series of trials than were necessary for control animals. The experimenters suggest that some factor in addition to delay is needed to explain the impairment on delayed-response tasks shown by animals with frontal lesions. (PsycINFO Database Record (c) 2006 APA, all rights reserved)