Situational determinants of the relative difficulty of simultaneous and successive discrimination.

Abstract

Each of four groups of rats learned two consecutive problems in a two-choice discriminative situation. Two groups were trained under conditions designed to facilitate the perceptual analysis of each pair of stimuli into components; the two members of each pair were separated in space, and the animal was required to jump directly to one member of the pair on each trial. In the remaining two groups, training was designed to promote perception of each pair of stimuli as a whole (configuration); the two members of each pair were spatially contiguous and the animal had to jump to a window at the right or left of the pair. Under component conditions successive discrimination was more difficult than simultaneous both in the first and in the second of the two consecutive problems, although there was some tendency for the difference in difficulty to decline from the first problem to the second. Under configurational conditions the simultaneous discrimination was more difficult in the first of the two problems, but the difference disappeared in the second (due principally to a marked improvement in the performance of the simultaneous group). In both problems the successive discrimination was more difficult under configurational than under component conditions.