| Motion vectors may be integrated by simple spatial averaging. Averaging
predicts perceived global motion in plaids, relatively simple stimuli obtained
by superposing two 1D modulations of luminance over space. Here you see
two kinds of plaid obtained by combining 1D modulations at different relative
orientations. In each plaid, the "true" motion is horizontal and to the
right. Note that the rightward motion is perceived in plaid (a), but not
in plaid (b). This happens because the vector average of the (a) components
is indeed horizontal and to the right, whereas the vector average of the
(b) components is down and to the right. More details on motion integration
in plaids are provided by comparing Adelson & Movshon (1982)
and Kim & Wilson (1993). |
