In Bruner's Information Hypothesis theory, Adaptation Level (A. L.) is used to acount for phenomena of assimilation. The present experiments were designed to test whether these phenomena were found under experimental conditions of lifted weight.
In Exp. 1, a lighter (about 200g) A. L. for white weights and a heavier (about 500g) A. L. for black weight were formed in a training series. Using Helson's comparative rating scales (Amer. J. Psychol. 1954, 321-326), subjects were required to make comparative judgments on five white weights (100, 150, 200, 250, 300g) with a white standard weight (200g), and then on five black weights (400, 450, 500, 550, 600g) with a black standard weight, five times for each weight. Then in a critical series, subjects were asked to make comparative judgments on a black standard weight (350g) with its white, subjectvely equal, weight which had been measured for each subject in a measuring series without visual cues. Likewise, a black, subjectively equal, weight was used with a white standard weight (350g). At the beginning of the critical series, an effect of contrast was found ; i. e., the black weight was judged lighter than the white one, and vice versa. But with an increas-ing number of judgments, the black weight tended to be judged heavier than the white one. (Fig 2)
In Exp. II, colors of the weights were changed, a heavier (about 500g) A. L. for white weights and a lighter (about 200g) A. L. for black weights were formed in a training series with the same provedure (except changed colors) as that of Exp. 1. In the critical series the black weight was generally judged heavier than the white. (Fig. 3)
In Exp. III, the natural tendency of lifted weight for different colors was ex-amined. Naive subjects with no experience of training series judged in critical series. It was found that the black weight was judged heavier than the white weight. (Fig. 4)
In Exp. IV, we examined whether subjectively equal weights would show any change under training series or with the lapse of time. After a training series subjects judged in a measuring series again. No differences were found between the results on the measuring series and those of the previous one except for one subject.
Assuming that we have the heavier A. L. for the black body than for the white one, the results in Exp. I could be explained in terms of contrast.
We must be careful in the application of the Adaptation-Level theory becouse there are phenomena of both constrast and assimilation which are phenomenally contradictory. But it is unknown what factors would determine the turning point from contrast to assimilation.
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