Abstract
The aim of this large-scale study was to find out which points along the contour of a shape are most salient and why. Many subjects (N=161) were asked to mark salient points on contour stimuli, derived from a large set of line drawings of everyday objects (N=260). The database of more than 200,000 marked points was analyzed extensively to test the hypothesis, first formulated by Attneave (1954), that curvature extrema are most salient. This hypothesis was confirmed by the data: Highly salient points are usually very close to strong curvature extrema (positive maxima and negative minima). However, perceptual saliency of points along the contour is determined by more factors than just local absolute curvature. This was confirmed by an extensive correlational analysis of perceptual saliency in relation to ten different stimulus factors. A point is more salient when the two line segments connecting it with its two neighboring salient points make a sharp turning angle and when the 2-D part defined by the triplet of salient points is less compact and sticks out more.
Article PDF
Similar content being viewed by others
References
Attneave, F. (1954). Some informational aspects of visual perception. Psychological Review, 61, 183–193.
De Winter, J., & Wagemans, J. (2004). Contour-based object identification and segmentation: Stimuli, norms and data, and software tools. Behavior Research Methods, Instruments, & Computers, 36, 604–624.
De Winter, J., & Wagemans, J. (2006). Segmentation of object outlines into parts: A large-scale integrative study. Cognition, 99, 275–325.
De Winter, J., & Wagemans, J. (in press). The awakening of Attneave’s sleeping cat: Identification of everyday objects on the basis of straightline versions of outlines. Perception.
Feldman, J., & Singh, M. (2005). Information along contours and object boundaries. Psychological Review, 112, 243–252.
Hoffman, D. D., & Richards, W. A. (1984). Parts of recognition. Cognition, 18, 65–96.
Hoffman, D. D., & Singh, M. (1997). Salience of visual parts. Cognition, 63, 29–78.
Kennedy, J. M., & Domander, R. (1985). Shape and contour: The points of maximum change are least useful for recognition. Perception, 14, 367–370.
Kennedy, J. M., Juricevic, I., & Bai, J. (2003). Line and borders of surfaces: Grouping and foreshortening. In H. Hecht, R. Schwartz, & M. Atherton (Eds.), Looking into pictures: An interdisciplinary approach to pictorial space (pp. 321–354). Cambridge, MA: MIT Press.
Koenderink, J. J. (1984). What does the occluding contour tell us about solid shape? Perception, 13, 321–330.
Koenderink, J. J., & van Doorn, A. J. (1976). The singularities of the visual mapping. Biological Cybernetics, 24, 51–59.
Koenderink, J. J., & van Doorn, A. J. (1982). The shape of smooth objects and the way contours end. Perception, 11, 129–137.
Norman, J. F., Phillips, F., & Ross, H. E. (2001). Information concentration along the boundary contours of naturally shaped solid objects. Perception, 30, 1285–1294.
Op de Beeck, H., Wagemans, J., & Vogels, R. (2001). Inferotemporal neurons represent low-dimensional configurations of parameterized shapes. Nature Neuroscience, 4, 1244–1252.
Op de Beeck, H., Wagemans, J., & Vogels, R. (2003). Asymmetries in stimulus comparisons by monkey and man. Current Biology, 13, 1803–1808.
Panis, S., De Winter, J., Vandekerckhove, J., & Wagemans, J. (in press). Identification of everyday objects on the basis of fragmented versions of outlines. Perception.
Panis, S., & Wagemans, J. (2007). Time-course contingencies in perceptual organization and identification of fragmented object outlines. Manuscript submitted for publication.
Pasupathy, A., & Connor, C. E. (1999). Responses to contour features in macaque area V4. Journal of Neurophysiology, 82, 2490–2502.
Pasupathy, A., & Connor, C. E. (2001). Shape representation in area V4: Position-specific tuning for boundary conformation. Journal of Neurophysiology, 86, 2505–2519.
Pasupathy, A., & Connor, C. E. (2002). Population coding of shape in area V4. Nature Neuroscience, 5, 1332–1338.
Resnikoff, H. L. (1989). The illusion of reality. New York: Springer.
Sabra, A. I. (1989). The optics of Ibn al-Haytham. London: Warburg Institute.
Snodgrass, J. G., & Vanderwart, M. (1980). A standardized set of 260 pictures: Norms for name agreement, image agreement, familiarity, and visual complexity. Journal of Experimental Psychology: Human Learning & Memory, 6, 174–215.
Vandekerckhove, J., Panis, S., & Wagemans, J. (2007). The concavity effect is a compound of local and global effects. Perception & Psychophysics, 69, 1253–1260.
Van Gool, L. J., Moons, T., Pauwels, E., & Wagemans, J. (1994). Invariance from the Euclidean geometer’s perspective. Perception, 23, 547–561.
Wagemans, J., De Winter, J., Op de Beeck, H., Ploeger, A., Beckers, T., & Vanroose, P. (in press). Identification of everyday objects on the basis of silhouette and outline versions. Perception.
Wagemans, J., Notebaert, W., & Boucart, M. (1998). Lorazepam but not diazepam impairs identification of pictures on the basis of specific contour fragments. Psychopharmacology, 138, 326–333.
Zusne, L. (1970). Visual perception of form. New York: Academic Press.
Author information
Authors and Affiliations
Corresponding author
Additional information
This research was supported by a research grant from the University Research Council (OT/00/007) and from the Fund for Scientific Research (FWO-Vlaanderen G.0189.02) to J.W.
After the first submission of the manuscript, Joeri De Winter died in a tragic accident.
Rights and permissions
About this article
Cite this article
De Winter, J., Wagemans, J. Perceptual saliency of points along the contour of everyday objects: A large-scale study. Perception & Psychophysics 70, 50–64 (2008). https://doi.org/10.3758/PP.70.1.50
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.3758/PP.70.1.50