To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jecp.2006.01.002 Byline: Ramesh S. Bhatt (a), Angela Hayden (a), Andrea Reed (a), Evelin Bertin (b), Jane Joseph (a) Keywords: Infancy; Object perception; Part perception; Concavity discrimination; Boundary perception Abstract: Object parts are signaled by concave discontinuities in shape contours. In seven experiments, we examined whether 5- and 61/2-month-olds are sensitive to concavities as special aspects of contours. Infants of both ages detected discrepant concave elements amid convex distractors but failed to discriminate convex elements among concave distractors. This discrimination asymmetry is analogous to the finding that concave targets among convex distractors pop out for adults, whereas convex targets among concave distractors do not. Thus, during infancy, as during adulthood, concavities appear to be salient regions of shape contours. The current study also found that infants' detection of concavity is impaired if the contours that define concavity and convexity are not part of closed shapes. Thus, for infants, as for adults, concavities and convexities are defined more readily in the contours of closed shapes. Taken together, the results suggest that some basic aspects of part perception from shape contours are available by at least 5 months of age. Author Affiliation: (a) Department of Psychology, University of Kentucky, Lexington, KY 40506, USA (b) University of Zurich, CH-8057 Zurich, Switzerland Article History: Received 3 October 2005; Revised 19 January 2006