Bias toward regular form in mental shape spaces

The distribution of figural "goodness" in 2 mental shape spaces, the space of triangles and the space of quadrilaterals, was examined. In Experiment 1 , participants were asked to rare the typicality of visually presented tria ngles and quadrilaterals (perceptual task). In Experiment 2, participants w ere asked to draw triangles and quadrilaterals by hand (production task). T he rated typicality of a particular shape and the probability that that sha pe was generated by participants were each plotted as a function of shape p arameters, yielding estimates of the subjective distribution of shape goodn ess in shape space. Compared with neutral distributions of random shapes in the same shape spaces, these distributions showed a marked bias toward reg ular forms (equilateral triangles and squares). Such psychologically modal shapes apparently represent ideal forms that maximize the perceptual prefer ence for regularity and symmetry.