Infants’ responsiveness to half-occlusions in phantom stereograms

Abstract

The present natural preference study investigated infants 4 and 7 months of age for their ability to respond to phantom contoubrs, illusory surfaces generated by half-occlusions in a stereoscopic display consisting of a pair of parallel vertical lines. The left line in the half-image for the right eye and the right line in the half-image for the left eye have a gap in the middle. The visual system accounts for the binocular unmatched gaps by perceiving an illusory contour. Infants in the experimental condition were presented with a standard phantom stereogram displaying a phantom contour versus a non-standard phantom stereogram, the half-images of which were exchanged. This stereogram evokes the impression of two small separate illusory contours. In both stereograms, the gaps moved up and down. The participants aged 7 but not 4 months preferred looking at the standard phantom stereogram. A control condition supported the hypothesis that the infants 7 months of age in the experimental condition indeed responded to the coherent illusory surface instead of simply detecting differences in the geometric arrangement of the half-occlusions. The results hence indicate that infants are able to extract spatial information from monocular regions in a binocular display.