Additivity of cues in conditional discrimination learning by rhesus monkeys.

Abstract

Four rhesus monkeys, trained to criterion on 90 conditional discrimination and discrimination reversal problems, were required to select 1 of 2 dissimilar geometrical forms in one context, and the other form in a 2nd context. The relevant cues for the correct choice were differences in (a) orientation of forms in horixontal and vertical planes, (b) color of forms, or (c) both color and orientation. 30 problems were learned under each condition. Monkeys solved discrimination problems with 2 cues more rapidly than those with only 1 cue. Multiple cues did not facilitate reversal learning. Sophisticated monkeys solve conditional discrimination and reversal problems with much greater facility than has generally been assumed, i.e., with fewer than 5 errors to criterion.