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要旨

It is usually assumed that the human visual system is most sensitive to the velocity of motion at
the retina. However, two optic flow velocity profiles that specify the same peak velocity can have
different durations and specify very different accelerations and displacements of the observer.
We compare heading and velocity discrimination in response to constant and raised cosine optic
flow velocity profiles. The experiment was divided into four separate blocks, heading discrimination
and velocity discrimination, with constant and raised cosine velocity profiles. On each trial, subjects
were presented with two consecutive movements (same velocity profile) through a limited lifetime
3-D star field and asked to indicate which motion was more to the right (heading discrimination)
or which had a faster maximum velocity (velocity discrimination). The heading experiments show
there is not a consistent preference of motion profile within the group but individual subject‘s
thresholds are significantly different between motion profile conditions. The different profiles in the
velocity experiments did not show as clear a pattern of results as those in the heading experiments.