Brief Research Interests - March 1995
My broad research goal is to explain the way in which the
human visual system transforms the images projected onto the two
retinas into a cohesive visual percept. Two fundamental aspects of
this transformation compose my main interest: spatial vision and
adaptation. By understanding spatial vision one learns how
information is derived from changes in light intensity across the
retinal image (for example, the information provided by a black and
white photograph). By understanding adaptation one learns how the
visual system alters itself to become well-suited for the immediate
environment (for example, increased light sensitivity at night).
Rather than focusing solely on spatial vision or adaptation, my
research examines the way in which adaptation changes spatial
vision. An example of this interaction is the transition from day
vision, when the visual system encodes fine detail clearly, to
night vision, when the visual system encodes detail coarsely.
The main thrust of my research approach is to create
quantitative models of adaptation processes based on human visual
psychophysics. This type of model can include information such as:
1) the relationship between stimulus exposure and adaptation
mechanism response, 2) the area of the retinal image to which the
process responds, and 3) the time-course of the adaptation. By
creating a computational model of the mechanism, the impact of the
adaptation can be predicted for a variety of circumstances. Such
predictions can be tested by making psychophysical measurements,
and the results can be used to further refine the model.
Additionally, by understanding neural mechanisms located early in
the visual system, we can anticipate the way high level mechanisms
might work. Basic neural circuits used early in the visual system
are likely to be used at higher brain centers for similar
operations on dissimilar inputs.