Related Experiment Videos
Dynamics of a divisive gain control in human vision
1Visual Sciences Center, University of Chicago, IL 60637, USA. hrw6@midway.uchicago.edu
Vision Research
|October 17, 1998
Summary
Human vision employs a divisive contrast gain control mechanism, influencing visual processing within 150 ms of stimulus onset. This gain control is spatially localized, impacting visual perception near the initial stimulus.
Area of Science:
- Visual neuroscience
- Perceptual psychology
- Human vision research
Background:
- Contrast gain control is a fundamental mechanism in visual processing.
- Previous research utilized the probe-on-flash technique in light adaptation studies.
Purpose of the Study:
- To provide evidence for a divisive contrast gain control in human vision.
- To characterize the temporal dynamics and spatial extent of this gain control mechanism.
Main Methods:
- Utilized a contrast-modified probe-on-flash technique.
- Measured visual thresholds for a flashed test pattern against a cosine mask.
- Varied the stimulus onset asynchrony (SOA) and mask contrast.
Main Results:
- Threshold elevations decreased monotonically up to 150 ms SOA, with an average time constant of 51 ms.
- Increment thresholds varied with mask contrast, confirming divisive gain control operation.
- The spatial spread of the gain control was found to be localized within a 45 arc min radius.
Conclusions:
- Human vision exhibits a divisive contrast gain control operating within the initial 150 ms post-stimulus.
- This gain control mechanism is spatially restricted, suggesting localized neural processing.
- The findings contribute to understanding the rapid adaptation and processing of visual information.