マグニチュード推定法によるエビングハウス錯視と評価順序効果の検討

The Ebbinghaus illusion and the evaluation-order effect were investigate dby using the magnitude estimation method. One center circle and four surround circles constituted the Ebbinghaus figure.There were seven kinds of diameter for the circles. Seven single circles with the same diameters were used as control. Subjects judged the apparent size of constituent circles of the Ebbinghaus figures and those of single circles. 56 subjects were randomly stationed two estimation-order conditions (i.e.，order from the center circle to the surround circle，or order from the surround circle to the center circle). Estimation displacement (％) were calculated from the estimated values for the constituent circles and for the corresponding single circle. We will summarize the Ebbinghaus illusion and evaluation-order effect as following. (1) The estimation displacement calculated from the first judgement caught the Ebbinghaus illusion. (2) There was a difference at estimation displacement of the center circle with the dependence on the estimation order，and the evaluation-order effect appeared. (3) Estimation displacement calculated from the second judgment contained both the Ebbinghaus illusion and the evaluation-order effect. (4)The estimation displacement of the center circle was made to decrease the size contrast in the Ebbinghaus illusion. (5)The degree of the overestimation was bigger than that of the underestimation. (6) The four surround circles may become af rame of reference，be cause the evaluation-order effect appeared only in the center circle.