Learning Set Formation in Slow Lorises (Nycticebus coucang)

Abstract

In primates, learning set formation has been reported in various simian species, but in only few prosimian species. The formation of visual discrimination learning set was tested on a nocturnal prosimian species, slow lorises (Nycticebus coucang). Their performance was higher than that of some New World monkeys. This confirmed the suggestion from the data on black lemurs (Lemur macaco) that there is an overlap between prosimians and simians in learning set ability.

Learning Set Formation in Common Tree Shrews (Tupaia glis)

“…The test problems were the same as in the experi ment on slow lorises [Ohta, 1983], They consisted of 197 pairs of two-dimensional patterns and 138 pairs of three-dimensional objects (made of 'junk' objects: toys, paper forms, urethane forms, etc. ).…”

“…The procedure of the simultaneous discrimination test with a noncorrection technique was also the same as that for lorises [Ohta, 1983]. Of 335 problems, 2 problems were used for habituation, 32 problems for a preliminary discrimination test, 300 problems for a discrimination test, and the last one for the complete learning test.…”

“…Follow ing the investigation of learning set forma tion in nocturnal slow lorises (Nycticebus coucang) [Ohta, 1983] and diurnal ring-tailed lemurs (Lemur catta) [Ohta et al, 1984], diurnal common tree shrews (Tupaia glis) were chosen as the third object for the inter specific comparison of learning set forma tion.…”

Learning Set Formation in Ring-Tailed Lemurs (Lemur catta)

“…The test apparatus was the same Wisconsin Gen eral Test Apparatus (WGTA) as used for the experi ment on slow loriscs [Ohta, 1983). During testing there was no light in the room except for a 100-watt white lamp fixed beneath the ceiling o f the test com partment.…”

“…Especial ly, the learning set performance is regarded to provide a reasonable measure of learning ability within the order of primates [Fobes and King, 1982]. One of the authors [Ohta, 1983] reported the learning set formation in nocturnal slow lorises (Nycticebus coucang), and the performance of them is higher than that of some New World monkeys. This con firmed the overlap between prosimians and simians suggested by the data on black le murs [Cooper, 1974], and also proposed the necessity of the interspecific comparison un der common experimental conditions.…”