An Advantage for Smooth Compared With Angular Contours in the Speed of Processing Shape

Bertamini, Marco and Palumbo, Letizia and Redies, Christoph (2019) An Advantage for Smooth Compared With Angular Contours in the Speed of Processing Shape. Journal of Experimental Psychology: Human Perception and Performance. ISSN 1939-1277

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Curvature along a contour is important for shape perception, and a special role may be played by points
of maxima (extrema) along the contour. Angles are discontinuities in curvature, a special case at one
extreme of the curvature continuum. We report 4 studies using abstract shapes and comparing polygons
(curvature discontinuities at the vertices) and a smoothed version of polygons (no vertices). Polygons are
simpler and are defined by a small set of vertices, whereas smoothed shapes have a continuous curvature
change along the contour. Angles have also been discussed as an early signal of threat and danger, and
on that basis, one may predict faster responses to polygons. However, curved shapes are more typical of
the natural environment in which the visual system has evolved. For a detection task, we found faster
responses to smooth shapes, not mediated by complexity (Experiment 1). We then tested 3 orthogonal
shape tasks: comparison between shapes (detection of repetition; Experiment 2a), comparison after a
rotation (Experiment 2b), and detection of bilateral symmetry (Experiment 3). In all tasks, responses for
smoothed stimuli were faster; there was also an interaction with type of response: Trials with smooth
shapes were faster when a positive response was produced. Overall, there was evidence that smooth
shapes with continuous change in curvature along the contour are processed more efficiently, and they
tend to be classified as targets. We discuss this in relation to shape analysis and to the preference for
smoothed over angular shapes.

Item Type: Article
Additional Information and Comments: Copyright 2019 American Psychological Association. This article may not exactly replicate the final version published in the APA journal. It is not the copy of record. The final, published version is available at
Keywords: perception, visual preference, curvature, complexity
Faculty / Department: Faculty of Science > Psychology
Depositing User: Letizia Palumbo
Date Deposited: 08 Aug 2019 08:21
Last Modified: 08 Aug 2019 08:21

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