ABSTRACT
Experimental and theoretical analyses of stimuli constitute the sine qua non of stimulus control research in the area of learning. According to traditional views of such situations, the elemental features of complex stimulus events compete for limited associative strength so that control by one element or stimulus dimension is gained at the expense of others. The functional stimulus may consist of patterns of change, relations among features, and so on—complex events whose invariant features are extracted from the flux comprised of seemingly more elemental events. Traditional views held that the proximal stimulus for visual perception consisted of a mosaic of light intensities on the retina from which the distal properties of the world were recovered through a reconstruction of sensory elements into a unified perceptual whole. The information about distance conveyed by a gradient of deformation provides a good example of a higher order "extended" stimulus.
