Abstract
Observers often fail to detect the sudden image change when multiple distracters are presented in the scene (change blindness as a result of mudsplashes). In previous study (VSS2008), we found that a single small flash may induce the blindness for the shape change of a moving target. In this study, we investigated whether the relative movement on the retina in terms of tracking a moving fixation point would induce the blindness for the shape change in a stationary target. A white target and/or red fixation point (19.1 × 19.0 arc min) went upward or downward with a constant velocity (9.8 arc deg/s) along a linear course. A flash stimulus (1.6 × 0.3 arc deg) was presented at 5.5 arc deg from the fixation point in the same visual field with the target. In the half of trials, the target changed its horizontal length to 57.3 arc min at the moment of the flash. The distance between the fixation point and target was horizontally 2.6 arc deg and vertically 5.8 arc deg when the target changed its shape. For the moving target with stationary fixation point, observers frequently failed to detect the shape change, especially in the lower visual field. For the stationary target with moving fixation point, observers failed to detect the shape change while the frequency of the failure was lower than that for the moving target. For the stationary target with stationary fixation point, such a frequent fail in change detection was not obtained. These results suggest that the frequent failure to detect the shape change for the moving object involves the processing for the object movement in the object-centered coordination, which has anisotropy between lower and upper visual fields, and the processing for the movement in the retinal coordination, which does not has such an anisotropy.