Effect of contrast on the perceived direction of a moving plaid

Magnitude of luminance modulation specifies amplitude of perceived movement

“…The optimal-fit values were k 1 = 1.11 and k 2 = 0.68 for A.P., and k, = 1.56 and k 2 = 0.68 for M.R. These estimates are close to k, = 1.99 and k 2 = 0.76 obtained by Stone et al (1990) in a completely different psychophysical setting. Figure 4 shows the transformed luminance contrastf(W) as a function ofthe adjusted displacement amplitude, expressed as a fraction of the interdot separation.…”

“…Thompson (1982) found, for example, that low-contrast gratings appear to move more slowly than a high-contrast reference moving at the same speed. This contrast dependence also implies that the perceived motion direction of a composite pattern can be considerably changed by selectively increasing the luminance of some components of this composite pattern (Allik, 1992;Stone et al, 1990). The results of the present experiment appear to reveal the same property of the underlying motion-encoding operation: The perceived amplitude of w-motion increases monotonically with relative contrast W. Many previous studies have proposed that the correspondence strength between two elements involved in motion increases with luminance flux (Burt & Sperling, 1981;Nishida & Takeuchi, 1990;Shechter & Hochstein, 1989;van Santen & Sperling, 1984;Werkhoven, Snippe, & Koenderink, 1990b).…”

“…saturates at low contrast (Campbell & Maffei, 1981;Derrington & Goddard, 1989;Derrington & Henning, 1987;Keck, Palella, & Pantle, 1976;Nakayama & Silverman, 1985;Stone, Watson, & Mulligan, 1990;Thompson, 1982). It has been proposed that the input signals undergo an amplitude-distorting nonlinearity before the motion information is determined.…”

Detection of temporal order of noise-like luminance functions

“…This would be interesting, since many experiments indicate a contrast saturation at stimulus contrasts above a few percent in human motion vision (see Stone, 1990, for a recent review).…”

Visual Motion Perception

“…In addressing plaid pattern motion, the model provides explanations of when plaid patterns cohere or do not (Adelson and Movshon, 1982;Kim and Wilson, 1993;Lindsey and Todd, 1995), how contrast affects the perceived speed and direction of moving plaids (Stone, Watson and Mulligan, 1990), and why the movement of so-called Type 2 patterns differs from those of Type 1 patterns Wilson, 1990, 1991;Yo and Wilson, 1992). All of these data may be be explained by an interaction of figure-ground separation mechanisms in the form cortical stream interacting with motion capture mechanisms in the motion cortical stream.…”