Local spatial distortion caused by simple geometrical figures

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.