- Motion Path Misidentification in the Periphery
Primary tabs
- View (active tab) Previous3 of 3
Description
Degree awarded: M.A. Psychology. American University Examination of motion illusions in central and peripheral vision has led to the ``feature blur'' hypothesis: the peripheral visual system combines features that the foveal visual system can separate. Others have hypothesized that processes that underlie crowding limit multiple object tracking. Here, I investigate the perception of motion paths of two objects that follow opposite rotational directions; I hypothesized that objects that follow the same path may produce misidentifications that depend on eccentricity. The stimulus consists of two 1-deg disks, one filled with a radial sine-wave pattern (concentric rings), the other with a tangential sine-wave pattern (spokes on a wheel); one disk rotates clockwise around a central point while the other rotates counter-clockwise. When viewed in the periphery, the disks often do not seem to follow circular paths but rather appear as an elliptical jumble of the two disks. In two experiments I measured the critical radius of the circular path (i.e., the size at which there is a transition between the percept of a circular path and jumbled ellipses) at several eccentricities; the results showed that the critical size as a function of eccentricity is similar to Bouma's law of crowding (slope between 0.1 and 0.5). In addition I found that the effect persists when one disk has high internal contrast and the other has low internal contrast--a finding that seems to separate motion path misidentification from standard crowding phenomena. Conclusion: motion path misidentification results may be consistent with a "feature blur" hypothesis; MPM in the visual periphery depends on eccentricity, similar in principle to Bouma's law, but may not share all aspects with visual crowding.
Downloaded 10 times
Stats
Viewed 244 timesDownloaded 10 times