Michael Kubovy - US grants

DESCRIPTION (provided by applicant): Deformations in atmospheric pressure vibrate an observers' eardrum; this causes waves to be formed in the cochlea, and as a result we are able to perceive sounds in the environment. Obviously, a qualitative model of this nature is insufficient as a model of auditory perception - and yet it is precisely this type of qualitative model that researchers have been forced to use when dealing Gestalt grouping principles. For example, we say that sounds that are similar are more likely to group together, or that sounds close together in time or pitch are more likely to group together, but the question is: How likely? What we desire is a way to quantify these grouping principles. In this research proposal, we outline new theory and an experimental paradigm, which will allow us to do just that. This proposal outlines a methodology for the quantification of Gestalt grouping principles in auditory perception. We have developed a new type of stimulus, the tone lattice, which is perceived by observers in one of two exclusively competing ways. By systematically manipulating pitch relations within a tone lattice, we are able to change the likelihood that observers will hear it organized in one way or the other. Measuring these changes in observer percept probability with respect to the experimentally manipulated pitch relations allows us to calculate functions, attraction functions, which can be used to predict observer perceptions. Attraction functions are measures of the strength of grouping. We are then able to introduce other features into our tone lattices, such as similarity of elements, to see how the attraction functions change. What we have in fact developed, is a sort of "yardstick" for quantitatively measuring the effect of Gestalt grouping principles on the segregation and formation of auditory objects.

When we look at the world, how do we know which parts of the visual input belong to the same object and which do not? The process known as perceptual grouping takes elements of the visual input and combines them into what we experience as a visual scene that contains objects, people, plants, shadows, and so on. Most of the time perceptual grouping is involuntary but it can come under voluntary control. For this reason, the study of perceptual grouping is a part of the larger effort toward understanding consciousness. Although phenomena of perceptual grouping are an essential foundation of perception, they are often described using a list of qualitative "principles," such as proximity, similarity, and good continuation, that are vague and unquantified. Michael Kubovy at the University of Virginia and Sergei Gepshtein at the Salk Institute for Biological Studies are proposing to clarify some of the fundamental processes of perceptual grouping, using rigorous methods of measurement and modeling. The researchers start with simple visual patterns that allow them to study one force of perceptual grouping at a time. The individual forces of grouping will then be combined, using more complex visual patterns, with the goal to derive general quantitative laws of perceptual grouping. The researchers will study the interaction of geometric factors (such as proximity between elements of visual displays) and intensive factors (such as the luminance and contrast of the elements) in perceptual grouping. The laws of combination of grouping factors will be compared with the laws of combination of other sensory cues, which have been intensively studied in the perception of visual depth and in multisensory integration.

Software to be developed for this research program will be made accessible to the public. In addition to addressing fundamental issues in visual perception, the work has the potential to influence developments in visual media such as art, animation, and film.