CONTRAST AND SIZE DEPENDENT INTERACTIONS IN HUMAN MOTION PERCEPTION

Title CONTRAST AND SIZE DEPENDENT INTERACTIONS IN HUMAN MOTION PERCEPTION
Author, Co-Author Luigi Bilotto, Gary Trick, Scott Steinman, Marie-Andree Deschamps
Topic
Year
1992
Day
Monday
Program Number
Poster 30
Room
Great Hall
Affiliation
Abstract Although visual sensitivity frequently varies with stimulus contrast and size, the effect of these variables on human motion perception is unclear. Here we describe the influence of contrast and size on motion perception for random dot kinematograms. Motion sensitivity was quantified by measuring direction discrimination thresholds for the correct detection of dot elements moving (12.5 deg/sec) in a common direction but embedded in a background of dots in random motion. The centrally fixated stimulus field subtended 24.5 deg, individual dots ranged from 7.5' to 30' and contrast levels were varied between 3% and 72%. Four visually normal volunteers (20-25 years of age) were studied. Our findings demonstrate that direction discrimination thresholds vary with both contrast and size. For all contrast levels, threshold was lower for large dots (30') than for small dots (7.5') but a pronounced interaction between dot size and contrast was evident. Varying contrast had a greater effect on motion sensitivity for small dots than for larger dots. At low contrast levels (POST - PUMP RETINOPATHY
Affiliation of Co-Authors
Outline