Role of Object-Contact Cues in Learning-Set Formation in Squirrel Monkeys

In studies of primate object discrimination learning it has been common procedure for animals to view and manually push aside the object of their choice on a given trial, thus permitcing access to the underlying food-well. Common household objeccs and toys have served as ready sources of varied stereometric objects with which to make long series of object discrimination problems characceristic of learning-set (LS) studies. The many dimensions of difference becween these objects make available co S a wide variery of cues for learning the discriminations. The objeccs of a given problem might differ not only with regard to a variety of visual cues, such as color, size, brightness, but with regard to a variety of cues arising from manual object concacr as well. The response of pushing aside objects might give rise co different kinesthetic cues according to the objects' sizes and configurations. Tactual sensations arising from couching the objects of one problem pair might be considerably unlike chose of the nexc pair. These rnacters gave rise to speculation as to the effect incurred upon LS formation as the cues normally arising from manual object contact are experimentally varied. The main question considered was: Given a series of discrimination problems in which visual discrimination of objects is possible, will the reduction of cues normally associated with manually contacting problem objeccs reduce rate of LS formation? It was predicted that it would reduce rate of LS formation, for reduction or exclusion of these cues would reduce the dimensions of object distinctiveness which could serve to permit reliable choices from trial to trial within a given problem.