The proposed research evaluates the role of several perceptual mechanisms in the processing of multidimensional stimuli. Based on a model of how perceivers integrate information across sensory dimensions, the proposed research uses information processing and psychophysical methods to examine interactions in vision, hearing, and touch. The first line of investigation employs two series of experiments to test the hypothesis that interacting dimensions are perceived according to a specific, primary orientation in psychological space. The first series uses a modification of Gerner's classification procedure to measure speed of processing at varying orientations of stimulus axes. The second series uses the INDSCAL procedure to scale transformed similarity ratings of these stimuli. The second line of investigation employs a newly-developed classification procedure to examine how different types of context constrain t.he processing of values on sensory dimensions. In the first series, this procedure is validated; pairs of interacting dimensions are catalogued into one of two types: (1) hard dimensions, those whose attributes are perceptually salient in complex contexts, or (2) soft dimensions, those whose attributes are veiled perceptually. In a second series, hard and soft dimensions are used to construct various three dimensional stimuli. The purpose is to identify processes operating on three dimensional stimuli, and to compare these processes with those involved in twodimensional perception. The comparisons are used to evaluate the generality of the proposed model. In a final series, two kinds of contextual influences are manipulated systematically: (1) level of intracategory variation; and (2) level of covariation between dimensions. These experiments are used to derive functions representing speed to access attributes from hard and soft dimensions. All experiments in this project are conducted with visual dimensions, auditory dimensions,.and vibrotactile dimensions, in order to encourage identification of general perceptual mechanisms of interaction. The proposed research represents, therefore, a broad and multipronged analysis of the processes underlying perceptual integration.
