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Spatial sampling of motion: seeing an object moving behind a picket fence
J L Dannemiller1, S M Heidenreich, T Babler
1Department of Psychology, University of Wisconsin-Madison 53706, USA. jldannem@facstaff.wisc.edu
Journal of Experimental Psychology. Human Perception and Performance
|December 31, 1997
Summary
Spatially sampled motion helps perceive object width when samples are close in time (90ms stimulus onset asynchrony). Performance degrades with increased temporal gaps or if motion path is disrupted.
Area of Science:
- Visual perception
- Computational neuroscience
- Psychophysics
Background:
- Spatially sampled motion involves discrete spatial positions with time-lagged luminance changes.
- The perceived width of a moving object is not directly observable.
Purpose of the Study:
- To investigate how spatiotemporal information in sampled motion specifies perceived object width.
- To determine the impact of stimulus onset asynchrony (SOA) and sample quantity on width perception.
Main Methods:
- Observers matched the perceived width of a spatially sampled moving bar to a static bar.
- Varying the stimulus onset asynchrony (SOA) between spatial samples.
- Assessing performance with different numbers of spatial samples.
Main Results:
- Accurate width perception occurred at an SOA of approximately 90 ms.
- Performance degraded significantly when SOA was doubled (180 ms).
- Increased number of samples improved performance if they maintained a smooth motion path and were viewed monocularly.
Conclusions:
- Spatiotemporal information within sampled motion can define a moving object's width.
- The utility of this information depends on the sampling preserving a coherent impression of motion.
- Temporal contiguity (low SOA) is crucial for effective width perception in sampled motion stimuli.