Two motion systems with common and separate pathways for color and luminance.

Goréa, Andrei; Papathomas, Thomas V.; Kovács, Ilona

doi:10.1073/pnas.90.23.11197

Cited by 17 publications

(9 citation statements)

References 59 publications

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“…13, p. 161), there are obvious demonstrations from human psychophysics of the perceived motion of isoluminant stimuli (14)(15)(16). Although the various degradations of motion perceived in isoluminant stimuli have led to speculations about special mechanisms for chromatic motion (17)(18)(19)(20)(21), lack of convincing experimental paradigms and results has left completely unresolved the question of how and where isoluminant motion might be computed, and there are supporters for all theoretical stands (22)(23)(24)(25)(26)(27)(28)(29).…”

mentioning

confidence: 99%

The mechanism of isoluminant chromatic motion perception

Lü

Lesmes

Sperling

1999

Proc. Natl. Acad. Sci. U.S.A.

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An isoluminant chromatic display is a color display in which the component colors have been so carefully equated in luminance that they stimulate only color-sensitive perceptual mechanisms and not luminance-sensitive mechanisms. The nature of the mechanism by which isoluminant chromatic motion is perceived is an important issue because color and motion processing historically have been associated with different neural pathways. Here we show that isoluminant chromatic motion (i) fails a pedestal test, (ii) has a temporal tuning function that declines to half-amplitude at 3-6 Hz, and (iii) is perceived equally well when the entire motion sequence is presented monocularly (entire motion sequence to one eye) versus interocularly (the frames of motion sequence alternate between eyes so that neither eye individually could perceive motion). These three characteristics indicate that chromatic motion is detected by the thirdorder motion system. Based on this theory, it was possible to take a moving isoluminant red-green grating and, by simply increasing the chromatic contrast of the green component, to generate the full gamut of motion percepts, from compelling smooth motion to motion standstill. The perception of motion standstill when the third-order mechanism is nullified indicates that there is no other motion computation available for purely chromatic motion. It follows that isoluminant chromatic motion is not computed by specialized chromatic motion mechanisms within a color pathway but by the third-order motion system at a brain level where binocular inputs of form, color, depth, and texture are simultaneously available and where selective attention can exert a major inf luence.An isoluminant chromatic display is a color display in which the component colors have been so carefully equated in luminance that they stimulate only color-sensitive perceptual mechanisms and not luminance-sensitive mechanisms. When an isoluminant display-e.g., a grating of alternating red and green stripes-is moved, the apparent movement is often reported to be perceptually different from the movement of ordinary displays, being neither as smooth nor as quick (1-8). In some instances, ''motion standstill'' of isoluminant displays has been reported (1-5), a phenomenon in which the moving display appears motionless but nevertheless is perceived as occupying different positions from time to time. Here we use a pedestal paradigm, the temporal tuning function, and a comparison between observers' performance in monocular and interocular presentations to infer that chromatic motion is perceived by the third-order motion system. The apparently poor quality of isoluminant motion is not intrinsic to chromatic motion but merely to the chromatic stimuli that have heretofore been generated. By manipulating the ratio of red-to-green contrast in accordance with the theory of third-order motion, we produce high-contrast, easily visible, isoluminant displays that exhibit the full gamut of motion percepts: from normal, easily perceived motion to mo...

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mentioning

confidence: 99%

The mechanism of isoluminant chromatic motion perception

Lü

Lesmes

Sperling

1999

Proc. Natl. Acad. Sci. U.S.A.

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“…Slow chromatic and fast achromatic motion systems have been proposed in the psychophysical literature (Burr et al, 1998;Gegenfurtner & Hawken, 1995Hawken et al, 1994;Gorea et al, 1993). Reaction time to motion onset (Burr et al, 1998), and motion identification thresholds (Gegenfurtner & Hawken, 1996) were found to increase more steeply for chromatic stimuli than for achromatic stimuli when using increasingly low physical stimulus speeds (or temporal frequencies).…”

Section: Discussionmentioning

confidence: 97%

“…This versatility has repeatedly been explained in terms of two (or more) separate and independent motion systems (Khuu & Badcock, 2002;van de Grind, van Hof, van der Smagt, & Verstraten, 2001;van der Smagt, Verstraten, & van de Grind, 1999;Burr, Fiorentini, & Morrone, 1998;Edwards, Badcock, & Smith, 1998;Verstraten, van der Smagt, & van de Grind, 1998;Gegenfurtner & Hawken, 1996;Gegenfurtner & Hawken, 1995;Nishida & Sato, 1995;Hawken, Gegenfurtner, & Tang, 1994;Barbur, Watson, Frackowiak, & Zeki, 1993;Gorea, Papathomas, & Kovacs, 1993;Cavanagh & Mather, 1989;Zihl, von Cramon, & Mai, 1983;Pantle & Picciano, 1976;Braddick, 1974). However, it is unlikely that all these motion systems exist, as this would lead to a very high number of motion systems (not to mention, all the possible interactions between those systems).…”

Section: Introductionmentioning

confidence: 93%

“…However, it is unlikely that all these motion systems exist, as this would lead to a very high number of motion systems (not to mention, all the possible interactions between those systems). We specifically investigated the widely supported division along the speed dimension, namely, the claim that human perception of motion is subserved by a fast and a slow motion system 1 (Khuu & Badcock, 2002;van de Grind et al, 2001;van der Smagt et al, 1999;Burr et al, 1998;Edwards et al, 1998;Verstraten et al, 1998;Gegenfurtner & Hawken, 1995Hawken et al, 1994;Gorea et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

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A Single System Explains Human Speed Perception

Boxtel¹,

Ee²,

Erkelens³

2006

Journal of Cognitive Neuroscience

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Motion is fully described by a direction and a speed. The processing of direction information by the visual system has been extensively studied; much less is known, however, about the processing of speed. Although it is generally accepted that the direction of motion is processed by a single motion system, no such consensus exists for speed. Psychophysical data from humans suggest two separate systems processing luminance-based fast and slow speeds, whereas neurophysiological recordings in monkeys generally show continuous speed representation, hinting at a single system. Although the neurophysiological findings hint at a single system, they remain inconclusive as only a limited amount of cells can be measured per study and, possibly, the putative different motion systems are anatomically separate. In three psychophysical motion adaptation experiments, we show that predictions on the basis of the two-motion system hypothesis are not met. Instead, concurrent modeling showed that both here-presented and previous data are consistent with a single system subserving human speed perception. These findings have important implications for computational models of motion processing and the low-level organization of the process.

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“…This is achieved by defining each element ofthe triplet {q, a, b} by the conjunction ofthese attributes, in a manner similar to our earlier class of stimuli (Gorea & Papathomas, 1991a;Papathomas & Gorea, 1988). We have already applied similar techniques using modified versions of the periodic stimuli of Figure 2 to examine the structure of the luminance and the chromatic motion pathways (Gorea, Papathomas, & Kovacs, 1993a, 1993b. These techniques can easily be extended and applied to the random-element stimuli presented in this paper to study the mechanisms and pathways underlying the perception of depth and static-flow patterns.…”

Section: Discussioniextensionsmentioning

confidence: 99%

A unified approach to the perception of motion, stereo, and static-flow patterns

Papathomas

Kovács

Goréa

et al. 1995

Behavior Research Methods, Instruments, & Computers

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This paper presents a unified approach for studying the perception of motion, stereopsis, and staticflow (Glass) patterns. The objective is to address the same issues across these "modalities." To this end, a new class of stimuli and procedures were developed, the key feature of which is the incorporation of a forced-choice competition paradigm into the random-dot stimuli paradigm that has traditionally been used in these modalities. The two competing percepts that are pitted against each other are opposite directions for motion, near/far depth planes for stereopsis, and orthogonal global patterns for Glass patterns. The differences in qualitative predictions for competing hypotheses are generally well pronounced, and the results provide clear evidence for deciding between alternative hypotheses. This approach has been used to confirm that covariance is the preferred metric for eliciting global correlations in all the modalities and to investigate the nature of front-end processes in each modality. It has the potential for neurophysiological studies for both single-cell and neuronal ensemble recording.

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Two motion systems with common and separate pathways for color and luminance.

Cited by 17 publications

References 59 publications

The mechanism of isoluminant chromatic motion perception

The mechanism of isoluminant chromatic motion perception

A Single System Explains Human Speed Perception

A unified approach to the perception of motion, stereo, and static-flow patterns

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