Visual and haptic perception of three-dimensional solid forms

Subjects sorted 24 solid forms into groups on the basis of perceived similarity of shape, and rated each on a series of physical attributes under either visual or haptic conditions. Multidimensional scaling analyses within each condition produced highly similar two-dimensional solutions. Both first dimensions were related to size judgments, and both second dimensions were related to shape judgments. Correlations between haptic and visual attribute ratings were high, and the between-attribute correlational structures within each condition were also very similar. The findings are discussed in terms of Gibson's notion of partial perceptual invariances.