Interactions between symmetry and elongation in determining reference frames for object perception

Many theories of object recognition posit that objects are encoded with res pect to a perceptual frame of reference. Such theories assume that factors such as symmetry and elongation are critical for the assignment of an objec t's primary axis, and consequently for the extraction of an object's refere nce frame. The present experiments directly examined the relative roles pla yed by symmetry and elongation in the determination of an object's primary axis, and the extent to which symmetry and elongation interact with one ano ther. We found that observers use both symmetry and elongation in extractin g an object's primary axis, that the extent to which each cue dominates dep ends on its relative salience, and that symmetry and elongation are process ed interactively, rather than in encapsulated modules.