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Flicker distorts visual space constancy
S L Macknik1, B D Fisher, B Bridgeman
1Psychology Board of Studies, Kerr Hall UCSC 95064.
Vision Research
|January 1, 1991
Summary
Flickering targets during eye movements distort space perception. Lower flicker rates made displacements easier to detect, suggesting flicker impacts visual processing and space constancy.
Area of Science:
- Visual perception
- Neuroscience
- Human factors
Background:
- Space constancy, the perception of a stable external world, is challenged during saccadic eye movements.
- Visual masking and extraretinal signals are thought to suppress the perception of visual displacement during saccades.
Purpose of the Study:
- To investigate the effects of target flicker frequency on the perception of spatial displacement during saccadic eye movements.
- To determine how flicker influences the detectability of target displacements relative to eye movement direction.
Main Methods:
- Participants performed a 2-interval forced-choice task to detect target displacements.
- A small target was flickered at frequencies of 33, 66, 130, or 260 Hz during saccades.
- Target displacement was tested in the direction of and opposite to eye movement.
Main Results:
- Displacement detection sensitivity was approximately twice as high when the target moved opposite to the eye movement compared to the same direction.
- Lower flicker rates (33 and 66 Hz) resulted in greater displacement detectability than higher rates.
- Detection was easier when the imposed displacement added to the expected illusory displacement during saccades.
Conclusions:
- Flicker significantly affects space perception and the detectability of spatial displacements during saccades.
- Both visual masking and extraretinal signals play crucial roles in suppressing displacement detection.
- Flicker, particularly at lower frequencies, may distort perceived space and impact visual stability, with implications for video display terminal use.