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08:34
The Measurement and Treatment of Suppression in Amblyopia
Published on: December 14, 2012
Nonmonotone backward masking functions and brightness reversals.
Alan L Stewart1, Dean G Purcell, Roger S Pinkham
1Stevens Institute of Technology, Hoboken, NJ, USA. alouisstewart@gmail.com
Attention, Perception & Psychophysics
|July 7, 2011
Summary
Increasing target luminance improves detection, but at intermediate intervals, higher luminance hinders it. This masking effect can cause brightness reversals, where the target appears brighter than its surroundings.
Area of Science:
- Visual perception
- Psychophysics
- Neuroscience
Background:
- Target detection is influenced by luminance contrast and masking.
- The Broca-Sulzer effect describes a non-monotonic relationship between stimulus luminance and perceived brightness.
Purpose of the Study:
- To investigate the effect of target-field luminance on visual detection under masking conditions.
- To explore the phenomenon of brightness reversal and its relation to masking functions.
Main Methods:
- Utilizing temporal and spatial forced choice tasks.
- Manipulating target-field luminance and the interval between target and mask onset.
- Analyzing observer performance, including instances of below-chance results.
Main Results:
- Increased target luminance initially aids detection but impairs it at intermediate target-mask intervals.
- Below-chance performance in spatial tasks suggests a brightness reversal of the target.
- Masking functions exhibit non-monotonic behavior.
Conclusions:
- The Broca-Sulzer effect model explains brightness reversals under masking.
- A generalized luminance summation model accounts for non-monotonic masking functions.
- Visual masking can lead to complex perceptual phenomena beyond simple detection thresholds.
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