Abstract
The Ebbinghaus illusion is a geometric illusion based on a size-contrast between a central circle and surrounding circles. A central circle surrounded by small inducing circles is perceived as being larger than a central circle surrounded by large inducing circles. In the present study we investigated 5–8-month-old infants' perception of the Ebbinghaus illusion by using a preferential-looking paradigm.
A total of 26 Japanese infants aged 5–6 and 7–8 months participated in this study. Infants were shown the overestimated figure and the underestimated figure of the Ebbinghaus illusion side by side. If infants perceive the Ebbinghaus illusion, the central circle of the overestimated figure appears larger than that of the underestimated figure. Therefore, we hypothesized that infants would show a preference for the overestimated figure.
We measured infants' preference for the over estimated figure in the following three conditions: normal condition, flash condition, and annulus condition. In the normal condition, the overestimated figure and the underestimated figure were shown in static. In the flash condition,the central circles were flashed, so that they attract infants' attention. In the annulus condition, only the inducing circles were shown. Results showed that 5–6 and 7–8 month-old infants preferred the overestimated figure of the Ebbinghaus illusion only in the flash condition. These results suggest that infants' preference reflects their perception of the size illusion of the central circle, indicating a perception of the Ebbinghaus illusion by 5–8-month-old infants.
This research was supported by PRESTO (Japan Science and Technology Agency) and a Grant-in-Aid for Scientific Research (18300090, 20119002) from Japan Society for the Promotion of Science.