@article{oai:nagoya.repo.nii.ac.jp:00008312,
 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 = {When two center circles (CCs) of identical size are presented side by side either in Ebbinghaus (E) illusion or in Delboeuf (D) illusion, these CCs look different in their size by the varieties of size difference between the surrounding circles (SCs) and the CC in E illusion or the concentric outer circle (COC) and the CC in D illusion. The purpose of this study is to examine the underlying relationship between E and D illusions, which have a similar appearance, through the effects of repeated presentations of E illusion on the magnitudes of D illusion. The black stimulus figures were printed on white sheets of paper(211×298mm)and bound as a booklet for experimental and control groups (Exp: D→E→D; Cont: D→rest→D). The magnitudes of illusion (MIs) of the CCs (dia: 20mm) in E and D illusions were measured by using magnitude estimation. These illusions were observed from a distance of about 40cm. The size ratios of E illusion (REs) between the SCs and the CC in E illusion were 1/2, 1/1, and 2/1. In the case of D illusion, the following size ratios (RDs) between the COC and the CC were used; RD = 4/2, 5/2, 7/2, 9/2, and 11/2. Variations in the MIs of E illusion were investigated by repeated presentations of three kinds of the REs 50 times each at random. Each presentation lasted for 20 seconds during a 50-minute observation. Meanwhile, variations in the MIs of D illusion were explored twice for each RD at random (one session) in Pre-and Post-tests. Subjects, 18 university students, were assigned equally and randomly into experimental and control groups, respectively. The experimental group underwent two sessions with D illusion before (Pre-test) and after (Post-test) the presentation of E illusion (50min). On the other hand, the subjects in the control group carried out the Pre-test, then they read a book for 50 minutes, then finally they took the Post-test. This experiment has revealed the following results. (1)The MIs of E illusion showed no significant variations with repeated observation (Fig.1). These MIs of the REs (1/2, 1/1, and 2/1) keep almost the same level in contrast either to the decrease of the MIs (Coren & Girgus, 1974) or to the shift to overestimation (Day, 1974; Goto, 1987, 1990; Goto & Ohya, 1989; Tanaka, 1989). (2)The MIs of D illusion shifted from overestimation to underestimation as the RD between the COC and the CC increased (Fig.2). This trend was similar to those found by Morinaga(1935) and Ogasawara(1952). However, the transition (zero point) from overestimation to underestimation occurred when the RD was quite smaler than the RDs found in their experiments. In addition, the descending tendencies were different between the Pre-test and Post-test in the experimental group. Although the repeated observation of E illusion didn't result in any significant variation in the MIs, it was found for the first time that the repeated observation of E illusion exerted suppressive effects on the MIs of D illusion. (3) In E illusion, the MIs represented the characteristic variations as a function of the RE between the SCs and the CC (Fig.3). These variations reflected clear size contrast between the surrounding circles and the center circle as suggested in our previous studies (Goto, 1978, 1980 a,b,1981, 1987, 1990; Goto & Ohya, 1989). In conclusion, this experiment has verified again E illusion as the "illusion of size contrast" through the magnitude estimation in the booklet method. Though the MIs of E illusion showed no significant variations in the repeated observations, the MIs of D illusion after the repeated presentation of E illusion were smaller than those before the repetition. As these suppressive effects seem to extend to any other illusions with the same background, the mechanisms generating E and D illusions might have no direct relation to each other despite the apparent similarity of their stimulus arrangements.},
 pages = {75--85},
 title = {Ebbinghaus錯視の反復観察にもとづくDelboeuf錯視の錯視量変化に関する実験的研究―ブックレット法を用いての検討―},
 volume = {37},
 year = {1991}
}