Local spatial distortion caused by simple geometrical figures

ABSTRACT

Dynamic distortion of the visual field has been shown to affect perceptual judgment of visual dimensions such as size, length, and distance. Here, we report four experiments demonstrating that the different aspects of a triangle differently influence judgments of distance. Specifically, when the base of the triangle faces the centre of the display, participants consistently underestimate and overestimate the distance of a small dot from the unmarked centre of the display relative to conditions in which the vertex of the triangle faces the centre. When the dot is close to the figure, the distance of the dot to the centre is underestimated. Conversely, when the dot is close to the figure, the distance to the centre is overestimated. The effect is replicated when the internal distances are equalized and when ellipses are used instead of triangles. These results support a ripple model of spatial distortion in which local curvature acts to attract or repel objects. In conclusion, we suggest some implications of our findings for theories of perceptual organization.

KEYWORDS:

• Visual space
• distortion
• Gestalt
• geometric figures
• perceptual grouping

Acknowledgements

The authors wish to thank the staff and students of the State Key Laboratory of Brain and Cognitive Sciences, Chinese Academy of Sciences, for their hospitality and logistical support. We would particularly like to thank Professor Lin Chen for making this research possible. We also thank Siyuan Hu, Wang Bo, and Venetia Harvey for their help in setting up and running the experiments and two anonymous reviewers for their helpful suggestions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. It should be noted that the current study investigated spatial relationships in the fronto-parallel plane and not in 3D space. Furthermore, it does not offer a view on the global geometry of visual space.

2. We cannot exclude the possibility that the reversal at 12 mm was caused by the relative inflation of the space in the base condition (see Figure 6A).

3. It is conceivable that the Müller-Lyer effect is caused by the spatial distortion described in the present study (Watson, 1978). However, a general treatment of this and other optical illusions is outside the scope of the paper.