Effects of Delboeuf Illusion on Pointing Performance

Abstract

It is not widely known that visual illusions that cause misrecognition with regard to the perception of length or width of figures affect human behavior. Thus, we investigate the influence of the Delboeuf illusion on pointing performance in this study. If the control circle of the Delboeuf illusion, which is the central circle of the Delboeuf illusion figure, is surrounded by a slightly larger circle, it is perceived to be larger than its actual size. On the contrary, if the control circle is surrounded by a much larger circle, it is perceived to be smaller than its actual size. Therefore, the Delboeuf illusion figure affects the perception of circle sizes and can also affect the movement time of pointing movements. The result indicates that there is no significant difference in the movement time and the error rate among three tasks---two tasks with the Delboeuf illusion and the other task without the Delboeuf illusion. Moreover, Fitts' law showed sufficient fits for all conditions. From these results, it can be said that the participants conducted the trials with the Delboeuf illusion as same as the trial without the Delboeuf illusion. This is because the participants saw the circles of the Delboeuf illusion at once in the questionnaire, but they saw the circles one by one during the trials so the illusion magnitude was difference between trials and a questionnaire.