Analysis of “Color-Form Cue Problem” in Japanese Monkey (Macaca fuscata yakui). I. Oddity Problem

Abstract

This experiment was designed to test the relative efficiency of color and form as cue with which Japanese monkeys can learn oddity problems.In the training periods, 4 Japanese monkeys were trained on 3-position oddity problems using stimuli shown in Fig. 1 and Table 1 with a modified WGTA. Six kinds of stimuli were used and they were divided into 3 groups of 2. Combinations and permutations of stimuli of 3 groups provided 18 different spatial configurations, which were randomly presented 4 times a day. A correction method was used. After criterion (more than 80% correct responses, 2 successive days) had been attained, monkeys were subjected to color-form cue dominance test on ambiguous oddity problems.In the test periods, each S received 96 trials a day for 6 days. A test trial was inserted every 4th trial. On a test trial, an ambiguous stimulus was substituted for one of the identical stimuli and it yielded two separate solutions arrived at by using two independent cue dimensions. For example, from left to right the stimulus objects might be a red ball, a red ball and a blue green cross on an original training trial, one of the red balls was changed to a blue green ball (ambiguous stimulus) on a test trial. A food reward would be obtained either by a color choice (red ball) or by a form choice (blue green cross) (1, 2, 3 in Fig. 3). On ambiguous oddity problems, there are 72 possible stimulus configurations, one third of which were randomly presented a day for 3 days. And the same procedure was duplicated.The learning processes of 4 Japanese monkeys on simple 3-position oddity problems are illustrated in Fig. 2. Results of testing support the previous findings that color is a more effective cue than form for macaque monkeys to solve oddity problems.Subsequently monkeys were given simple 3-position oddity problems which consist of the possible combinations of unidimensional stimuli shown in Fig. 1. Color-oddity problem and form-oddity problem were randomly presented 72 trials a day for 3 days. In this test, the transfer effect to these problems from previous oddity training was observed (Fig. 2, Table 3), and it was found again that in these simple oddity situations color cue is more dominant than form cue.