Infant perception of von Szily contours

• Published in: Journal of experimental child psychology Vol. 184; pp. 82 - 97
• Main Authors: Kavšek, Michael, Braun, Stephanie
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2019
• Subjects: Half-occlusions; Illusory contours; Infant vision; Perceptual development; Stereoscopic vision; Subjective contours; von Szily contours; Illusory contours; Half-occlusions; Subjective contours; Infant vision; Stereoscopic vision; Perceptual development; von Szily contours
• ISSN: 0022-0965; 1096-0457
• DOI: 10.1016/j.jecp.2019.04.001

•This is the first study to investigate infants’ perception of subjective von Szily contours.•In von Szily figures, stereoscopic cues define two overlapping surfaces.•Infants aged 4 and 5 months responded to the stereoscopic depth differences.•Infants 5 months of age displayed modal completion of the foreground surface.•Infants 5 and 7 months of age have developed some ability to conduct amodal completion of the background surface. This habituation–dishabituation study examined infants’ perception of subjective von Szily contours, the illusory effect of which is generated by horizontal disparity and half-occlusions. In these contours, a foreground surface appears to partially occlude a background surface. In Experiment 1, participants aged 4 and 5 months were habituated to a von Szily figure and were then tested for their ability to perceive the difference between the habituation figure and the same figure with reversed depth relations. The infants displayed significant novelty preferences during the posthabituation period. This observation indicates that 4- and 5-month-olds respond to the stereoscopically specified depth difference between the two surfaces of von Szily figures. In Experiment 2, participants aged 4 and 5 months were tested for the ability to conduct modal completion, that is, to perceive the surface that is stereoscopically shifted into the foreground as a whole. The infants were habituated to a von Szily figure and then examined for their ability to distinguish between complete and incomplete versions of the foreground surface. Longer looking at the incomplete posthabituation pattern indicates modal completion; the infants recognize the complete pattern as familiar and regard the incomplete pattern as novel. Similarly, Experiment 3 investigated whether infants aged 5 and 7 months amodally complete the background surface, that is, the surface that is partially covered by the foreground surface. Experiment 2 found modal completion in 5-month-olds. Experiment 3 established that 5- and 7-month-olds have developed some ability to conduct amodal completion. In sum, infants perceive the depth information in von Szily contours and conduct modal and amodal completion.