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Orang-utans and chimpanzees can discriminate between two objects on the basis of tactile cues and select the one that matches a visually presented sample.

Six adult chimpanzees that had been reared for the first two years of life in restricted laboratory environments were inferior in cognitive skills to eight wild-born control subjects, as assessed by Transfer Index testing. Since both groups had shared the same cages and test experiences after three to four years of age, the role of early experience in cognitive development was underscored.Research with nonhuman primates on the question of whether or not early impoverished rearing might result in cognitive deficits has produced contradictory results and conclusions. Harlow and his associates (Harlow, Harlow, Schiltz, & Mohr, 1971; Harlow, Schiltz, & Harlow, 1969) have reported that totally isolated rhesus monkeys (Macaco, mulatto) were not inferior in learning compared to control monkeys raised in semisocial isolation. In contrast, Davenport and his associates (Davenport & Rogers, 1970) have reported that chimpanzees (Pan) raised in restricted, impoverished conditions were inferior to control, feral-born chimpanzees which had been maintained in social groups. Restrictedly reared chimpanzees appeared to be relatively less adaptive

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19 juvenile chimpanzees, most of them with extremely limited previous social and object experience, were housed together in 17 successive groupings of 3 animals: the 1st trio consisted of individuals A, B and C; the 2nd of B, C and D; the 3rd of C, D and E, and so on. Each such ‘social generation’ was tested with the same two toys. Initially both objects were avoided or approached with caution. In the 3rd trio, however, individual E habituated to one object and in the 5th trio individual F habituated to the other object. An enduring tradition of boldness and play then ensued for each object separately. The traditions were more stable across groups as a whole than within individuals.

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