Simultaneous motion contrast across space: Involvement of second-order motion?

Department of Psychology, Faculty of Letters, University of Tokyo, Tokyo, Japan
Vision Research (Impact Factor: 1.82). 02/1997; 37(2):199-214. DOI: 10.1016/S0042-6989(96)00112-5


A static or counterphase (target) grating surrounded by drifting (inducer) gratings is perceived to move in the direction opposite that of the inducers. We compared the relative magnitudes of these simultaneous motion contrast generated by both first-order and second-order stimuli. The first-order stimuli were sinusoidal luminance-modulations of a uniform field, and the second-order stimuli were sinusoidal contrast-modulations of a random-dot field. When the target was a static grating, the second-order stimuli induced little motion contrast, while the first-order stimuli of the same effective contrast produced clear motion contrast. When the target was a counterphase grating, both first- and second-order stimuli produced clear motion contrast. These results are discussed in relation to the involvement of second-order motion pathways in the relative-motion processing, and the two types of motion aftereffects obtained with static and dynamic test stimuli.

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Available from: Mark Edwards, Jun 26, 2014
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    • "A control experiment was conducted to ensure there was no contamination of the secondorder stimuli by any psychophysical nonlinearities in the observers' visual systems. The procedure was similar to that used by several others (e.g., Ledgeway & Smith, 1994; Nishida, Edwards, & Sato, 1997). Specifically, observers were shown a four-frame stimulus interleaving two frames of containing a luminance-modulated grating, and two frames containing contrast-modulated random noise. "
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    ABSTRACT: As stimulus size increases, the direction of high-contrast moving stimuli becomes increasingly difficult to perceive. This counterintuitive effect, termed spatial suppression, is believed to reflect antagonistic center-surround interactions--mechanisms that play key roles in tasks requiring sensitivity to relative motion. It is unknown, however, whether second-order motion also exhibits spatial suppression. To test this hypothesis, we measured direction discrimination thresholds for first- and second-order stimuli of varying sizes. The results revealed increasing thresholds with increasing size for first-order stimuli but demonstrated no spatial suppression of second-order motion. This selective impairment of first-order motion predicts increasing predominance of second-order cues as stimulus size increases. We confirmed this prediction by utilizing compound stimuli that contain first- and second-order information moving in opposite directions. Specifically, we found that for large stimuli, motion perception becomes increasingly determined by the direction of second-order cues. Overall, our findings show a lack of spatial suppression for second-order stimuli, suggesting that the second-order system may have distinct functional roles, roles that do not require high sensitivity to relative motion.
    Preview · Article · Nov 2011 · Journal of Vision
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    • "Support for this explanation comes from studies of induced motion, in which a static target appears to move when embedded in a moving background (e.g. Ido, Ohtani & Ejima, 1997; Nishida, Edwards & Sato, 1997), as well as the finding that stationary references influence perceived speed (Gogel & McNulty, 1983; Blakemore & Snowden, 2000; Nguyen‐Tri & Faubert, 2007). "
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    ABSTRACT: How does nearby motion affect the perceived speed of a target region? When a central drifting Gabor patch is surrounded by translating noise, its speed can be misperceived over a fourfold range. Typically, when a surround moves in the same direction, perceived centre speed is reduced; for opposite-direction surrounds it increases. Measuring this illusion for a variety of surround properties reveals that the motion context effects are a saturating function of surround speed (Experiment I) and contrast (Experiment II). Our analyses indicate that the effects are consistent with a subtractive process, rather than with speed being averaged over area. In Experiment III we exploit known properties of the motion system to ask where these surround effects impact. Using 2D plaid stimuli, we find that surround-induced shifts in perceived speed of one plaid component produce substantial shifts in perceived plaid direction. This indicates that surrounds exert their influence early in processing, before pattern motion direction is computed. These findings relate to ongoing investigations of surround suppression for direction discrimination, and are consistent with single-cell findings of direction-tuned suppressive and facilitatory interactions in primary visual cortex (V1).
    Preview · Article · Nov 2009 · Vision research
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    • "A modified minimum motion technique (Anstis & Cavanagh, 1983; Nishida, Edwards, & Sato, 1997; Seiffert & Cavanagh, 1998) was used to find the subjective equiluminance value for second-order patterns. Subjects fixated a point at the center of the screen. "
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    ABSTRACT: Motion perception influences perceived position. It has been shown that first-order (luminance defined) motion shifts perceived position across a wide range of spatial and temporal frequencies. On the other hand, second-order (contrast defined) motion shifts perceived position over a narrow range of temporal frequencies, regardless of spatial frequency [Bressler, D. W., & Whitney, D. (2006). Second-order motion shifts perceived position. Vision Research, 46(6-7), 1120-1128]. These results suggest the presence of distinct position assignment mechanisms for first- and second-order motion. We investigated whether the first- and second-order systems independently encode and assign the position of a moving stimulus. To measure motion induced position shift we presented two horizontally offset Gabors placed above and below a central fixation point, with sine wave carriers drifting in opposite directions. Subjects judged the position of the top Gabor relative to the bottom one. We used both first-order Gabors (sinusoidal luminance modulation of a dynamic noise carrier enveloped by a static Gaussian) and second-order Gabors (sinusoidal contrast modulation of a dynamic noise carrier enveloped by a static Gaussian). Results showed a strong position shift in the direction of the carrier motion when both Gabors were first-order, a weak position shift when both Gabors were second-order, and no appreciable position shift when one Gabor was first-order and the other was second-order (cross-order motion). The absence of a position shift using cross-order motion supports the hypothesis that the two motion systems independently encode and assign the position of a moving object. These results are consistent with those of experiments investigating global spatial interactions between static first-order and second-order Gabor patches, indicating a commonality in the underlying spatial integration processes.
    Full-text · Article · Aug 2008 · Vision research
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