Harold Sedgwick, PhD
SUNY College of Optometry
33 West 42nd Street New York, NY 10036

Research Description

 

Surface Mediated Integration of Stereopsis and Perspective

Much of our behavior depends upon accurate perception of the 3-dimensional spatial layout of the environment.  Multiple sources of visual information are available to specify this layout, including stereopsis, motion parallax, shading and perspective.  This raises the question of how the visual system combines these sources of information, which is also referred to as the problem of sensory fusion. I and Dr. Barbara Gillam (U. of New South Wales in Australia) are exploring the role of perceptual surfaces in mediating the integration of two kinds of information for space perception: stereopsis and perspective. By integrating the local stereoscopic information relating an object to a surface with the stereoscopic and perspective information operating across the entire extent of the surface, the visual system can potentially greatly enhance the accuracy and precision with which the object's spatial location is perceived.  It has already been shown that the perceived slant of a background surface can influence the perceived relative depth of two probes suspended in front of the surface.  Our projects use this paradigm to investigate the processes by which local depth signals and surface slant signals are integrated.  We use computer generated stereoscopic displays. The first questions relate to what surface characteristics facilitate surface mediated integration of information for probe depths.  Another area of interest is the "topography of surface mediation".  A third series of questions looks at the relative effects on perceived probe depth of different types of information specifying surface slant.  They examine perspective, gradients of stereoscopic discontinuity at surface boundaries and a closely related form of information produced by gradients of texture discontinuity at surface boundaries.  Finally, we are also interested in studying the perceptual response to inconsistent information about the relative depth of the probes. 

Education

 

Deep Springs College, 1962-1965

Cornell University, BA (Psychology), 1967

Cornell University, PhD (Experimental Psychology) with James J. Gibson, 1973

New York University, MS (Computer Science) with Malcolm Harrison, 1986

Professional Positions

 
  • 1971-1974: Postdoctoral Fellow with Leon Festinger, Graduate Faculty of the New School for Social Research

  • 1974-1980: Assistant Professor, Behavioral Sciences, SUNY College of Optometry

  • 1980-Present: Associate Professor, Vision Sciences, SUNY College of Optometry

  • 1991: Visiting Professor, University of New South Wales, Australia

Recent Research Support

 

Surface Mediated Interaction of Stereopsis and Perspective (with B. Gillam). NSF 2000-2004.