Abstract
This study investigated 5-, 6- and 7-month-old infants' perception of the corridor illusion (n = 20 to 24 in each age group). The two older age groups were tested under monocular and binocular conditions and the youngest group viewed the displays binocularly. After 4 habituation trials, infants viewed two displays, presented side by side, during 8 test trials. In each display, the image of an object moved back and forth along a pictorial corridor. For adult observers, linear perspective created the impression that the objects approached and receded in depth. In the “constant size” display, changes in the object's image size were consistent with those of a constant sized object moving in depth: image size decreased as the object appeared to move farther away and increased as it appeared to move closer. In the “varying size” display, changes in image size were consistent with those of an object that became larger as it receded and smaller as it approached: image size increased as the object appeared to move farther away and decreased as it appeared to move closer. The infants in all age groups exhibited significant looking preferences for the varying size display. This preference could not have been based on retinal image size, because the same image sizes were shown in the two displays. The infants apparently perceived that the object in the varying size display changed in size as it moved, while the object in the constant size display remained the same size. Viewing conditions had no effect in any age group. This suggests that size may have been perceived on the basis of relational information rather than perceived change in depth. The results do suggest that 5- to 7-month-old infants perceive the corridor illusion and can achieve size constancy in pictorial displays.