@article{oai:nagoya.repo.nii.ac.jp:00008318,
 author = {後藤, 倬男 and GOTO, Takuo},
 journal = {名古屋大学文学部研究論集　哲学},
 month = {Mar},
 note = {The purpose of this study was to examine the effects of the stimulus conditions on the magnitude of illusion (MI) by using Baldwin illusion (BI) which has similar figure constellation to Ebbinghaus illusion (EI), as shown in Fig.1. The MI in the size of a center circle (CC) was measured under the following two kinds of stimulus-condition: (1) the size ratio (R;R=1/4, 1/2, 1/1, 3/2, 2/1, 3/1,and 4/1) of the surrounding circles (SCs) to the CC, and (2) the distance (D) between the SCs and the CC (D=5.3, 10.6, 21.3, and 42.5mm). Two personal computers (NEC: PC-9801XA) were used for presenting 29 standard stimuli (SS: 7 size ratios×4 distances＋1 control stimulus) and a comparison stimulus (CS) to the subjects located 115 cm away from the display. Twentyfive subjects, students with normal vision, were instructed to compare the apparent size of the SS presented randomly at the center of one display (NEC: N-5923) with that of the CS (a single circle) presented on the another display (NEC: N-5923). The size of the CS was changed through the method of limits. Each subject was exposed to the SS and CS in the order of L (SS:left,CS: right)- R(SS:right, CS:left) and vice verse. This study revealed the two distinct results as follows. First, the MIs showed the characteristic variations as a function of the size ratio between the SCs and the CC (Fig.2). These variations, having clear maximum in underestimation, reflected the size contrast between the SCs and the CC within the limited range of the size ratio (1/2～3/2) between these two figure segments as suggested in our previous studies (Goto, 1978, 1980a, 1981, 1987, 1991;Goto & Ohya, 1989). On the other hand, the MIs showed a nearly parallel shift to the overestimation as the distances between the SCs and CC decreased. This tendency seemed to indicate the cohesive interaction between the SCs and the CC (Coren & Girgus, 1974, 1978; Girgus,et al., 1972). However, the size ratios having the maximum MI in underestimation were different from each other according to the distances between the SCs and the CC. Consequently, the size contrast between the SCs and the CC may be more significant than the cohesive force in the BI as well as in the EI. Then, as shown in Fig.3, the above tendencies were differentiated into two groups of subjects by using cluster analysis. The simple decrease of overestimation (increase of underestimation) and parallel MI's difference by the distances between the SCs and the CC were more dominant in Group Ⅰ(subject:14). While, decrease of underestimation after the maximum was more dominant in Group Ⅱ(11), and there was no effects of the D in this group. However, this tendency was different from that observed in our previous study (Goto & Hanari, 1991). Consequently, the other factors might be introduced in place of the abovementioned cohesive factor. The differences of the apparent depth in each figure segments (circles) of the SSs and CC were reported by the subjects. Systematic difference in observation may be adopted differentially by the above two groups for judging the depth of these segment circles. This third factor as a mechanism of BI and EI may be introduced to explain the above different tendencies in the MI variations owing to the different observing ways between two groups.},
 pages = {111--122},
 title = {Baldwin錯視の刺激条件に関する一考察},
 volume = {38},
 year = {1992}
}