Gurnsey, R., Fleet, D.J., and Potechin, C.
Second-order motions contribute to vection.
Vision Research 38: 2801-2816, 1998
First and second-order motions differ in their ability to induce motion
aftereffects (MAEs) and the kinetic depth effect (KDE). To test whether
second-order stimuli support computations relating to motion-in-depth
we examined the vection illusion (illusory self motion induce by image
flow) using a vection stimulus (V, expanding concentric rings) that
depicted a linear path through a circular tunnel. The set of vection
stimuli contained differing amounts of first- and second-order motion
energy (ME). Subjects reported the duration of the perceived MAEs and
the duration of their motion percept. In Experiment 1 both MAEs and
vection durations were longest when first-order (Fourier) components
of V were present in the stimulus. In Experiment 2, V was multiplicatively
combined with static noise carriers having different chack sizes. The
amount of first-order ME associated with V increases with check size.
MAEs were found to increase with check size but vection durations were
unaffected. In general MAEs depend on the amount of first-order ME
present in the signal. Vection, on the other hand, appears to depend
on a representation of image flow that combines first and second-order ME.
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