Related Experiment Videos
Brightness assimilation in bullseye displays
Daniel Bindman1, Charles Chubb
1Institute for Mathematical Behavioral Sciences, University of California at Irvine, Irvine, CA 92697-5100, USA. dbindman@uci.edu
Vision Research
|December 3, 2003
Summary
Brightness contrast illusions can be reversed using specific "bullseye" display patterns. These novel visual stimuli demonstrate assimilation, where a gray target appears darker or lighter based on surrounding alternating color bands, challenging existing visual models.
Area of Science:
- Visual perception
- Psychophysics
- Computational neuroscience
Background:
- Simultaneous brightness contrast typically makes a gray target appear brighter when bordered by black than by white.
- Existing models of visual contrast perception do not fully explain all observed phenomena.
Purpose of the Study:
- To investigate the reversal of simultaneous brightness contrast effects using novel "bullseye" display patterns.
- To explore the phenomenon of assimilation in visual perception under specific stimulus conditions.
Main Methods:
- Experiments utilized a two-alternative forced-choice (2AFC) design with varying target contrasts and surround band widths.
- A method of matching was employed in a subsequent experiment to verify findings.
- Stimuli featured a central gray target square surrounded by alternating black and white bands.
Main Results:
- "Bullseye" displays induced assimilation, causing the gray target to appear darker than in standard contrast displays.
- Assimilation was maximal at negative target contrast and decreased with increasing contrast.
- Results varied significantly between 2AFC and method of matching, indicating complex perceptual interactions.
Conclusions:
- Assimilation effects in bullseye displays are not predicted by current models like CSF, anchoring, or ODOG.
- A contrast inhibition mechanism is proposed to explain the observed assimilation.
- The findings highlight the need for refined models of visual contrast processing.