Research Bursary Program
Supervisor Project Proposal (Summer 2014)
Supervisor Last Name: Kingdom
Supervisor First Name: Frederick
McGill Dept/School: McGill Vision Research, Dept. Ophthalmology
Faculty Professor (Full, Associate or Assistant): Full
Email: fred.kingdom@mcgill.ca
Phone No. (optional): 514-934-1934 x35308
Research Field: Visual Neuroscience
Proposal No. (1 or 2): 1
Research Location (McGill or affiliated institution): RVH
Ethics approval will be required for proposed project (Yes/No): No
Proposed project will involve chart reviews (Yes/No): No
Project Title (maximum 1 line): Curvature processing in human vision
Hypothesis/Question to be Addressed (maximum 4 lines):
The project will test the hypothesis that neurons in the visual system sensitive to curvature respond in the same
way irrespective of the viewing distance of the observer to the curve. Psychophysical (behavioural) methods
using computer-generated test patterns with normal human test subjects will determine whether curvature is
encoded by the visual system in units of physical size, as predicted by the hypothesis, or in units of visual angle, as
for many visual features.
Specific Aims (maximum 10 lines):
The visual detection of the curvatures of an object’s outline is essential to object recognition. Curvature is the
rate at which orientation changes across space, and if the curve is part of a circle, curvature can be expressed as
the reciprocal of the radius of the circle. As one moves away from an object, the curvatures of its outline increase
when measured in units of visual angle, but do not change when measured in units of its physical size.
Physiological evidence has shown that the visual system possesses neurons selective for different curvatures, but
it remains unclear as to whether these neurons are selective to curves defined in units of visual angle (e.g. arc
degrees) or physical size (e.g. centimetres). To test between the two possibilities, normal human subjects will
make a large number of comparative judgments of the curvatures of contours with different curvatures and
lengths. The curves will be presented in pairs on a computer screen, and one of the curves will be adjusted by the
test subject to match the other using a key pad, with all adjustments recorded by computer to ensure objectivity.
The results of the experiments will be analyzed to determine whether the human visual system encodes curves in
units of object size or visual angle.
Role of Student (maximum 15 lines):
The student will be involved in all aspects of the project. The student will read background material on visual
neuroscience and psychophysical methods, as well as specialized articles on curvature and shape processing. The
student will run himself/herself as a test subject as well as other volunteer test subjects on all experiments. The
student will carry out all aspects of data analysis, and in doing so learn to use MATLAB as well as graph-plotting
software. The student will write a final report of the project. Although computers will be used for all stages of
the project, the student will not be expected to write the software for the actual experiments.