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Eric Hiris, Christine Cramer; How much does biological motion perception depend on motion?. Journal of Vision 2005;5(8):22. doi: 10.1167/5.8.22.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: When presented with a single frame, naïve observers do not spontaneously recognize it as a human figure. However, non-naïve-observers can perceive biological ‘motion’ from a static display. Static frame conditions and conditions with poor motion quality may provide the key to discovering how much biological motion perception depends on form or motion perception. Method: Motion quality was degraded in three ways: inserting blank frames, displaying motion out of order, and decreasing the number of frames presented. Two animation conditions were used, one where blank frames were presented between each frame of the animation sequence and another where each frame remained visible until the next frame was presented. The animation sequences contained 1, 3, 6, 12, 23, or 45 frames presented over a 1.1 second period. Observers indicated whether the first or second of two presentations contained a point light walker among scrambled walker masking dots. Results: There was no difference between the two animation conditions. In the one frame condition, observers required about 25 mask dots to mask biological ‘motion.’ However, as the number of frames increased beyond six frames, more masking dots were required to mask biological motion. This increase was much more pronounced for animation sequences presented in order compared to those presented out of order. Conclusions: Adding motion to the display does not seem to have an effect until the motion quality is about twelve frames per second. Specifically, performance in the three and six frame conditions, where the motion quality was poor, was similar to performance in the 1 frame (no motion) condition. This suggests that under poor motion quality conditions, form perception may play a large role in perceiving biological motion and may be more useful to consider than short- versus long-range motion processing distinctions.
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