Psychophysical studies of shape with Fourier descriptor stimuli.

The Fourier descriptor (FD) method of shape representation provides a convenient description for the outlines of shapes. It can also be used to generate orthogonal patterns (FD stimuli) which are uniquely characterized by their frequency, amplitude, and phase. Psychophysical studies were conducted to assess threshold tuning properties and frequency specificity during adaptation to FD stimuli. The results suggest the operation of filters which are characterized by the parameter 'curvature frequency'.