The Perception of Motion in Chromatic Stimuli

University of Melbourne, Australia.
Behavioral and Cognitive Neuroscience Reviews 10/2005; 4(3):192-217. DOI: 10.1177/1534582305285120
Source: PubMed

ABSTRACT The issue of whether there is a motion mechanism sensitive to purely chromatic stimuli has been pertinent for the past 30 or more years. The aim of this review is to examine why such different conclusions have been drawn in the literature and to reach some reconciliation. The review critically examines the behavioral evidence and concludes that there is a purely chromatic motion mechanism but that it is limited to the fovea. Examination of motion performance for chromatic and luminance stimuli provides convincing evidence that there are at least two different mechanisms for the two kinds of stimuli. The authors further argue that the chromatic mechanism may be at a particular disadvantage when the integration of multiple local motion signals is required. Finally, the authors present a descriptive model that may go some way toward explaining the reasons for the differences in collected data outlined in this article.

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Available from: Sophie M Wuerger, Sep 26, 2015
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    • "The relatively uniform nature of the discrimination space compared to the asymmetrical and quite idiosyncratic form of the free-categorical space suggests that the observers are clearly performing different tasks even though the stimulus set remains unchanged for each task. We suggest that the free-categorisation task examined here may be the simplest form of colour sensation, and provides some intermediate psychophysical measure of colour perception between discrimination and colour-naming, and we speculate that its neural analogue may be the population response of colour selective neurones seen in V1 [105], [106], a suggestion made previously in the context of chromatic motion discrimination [107]. "
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    ABSTRACT: In this paper, we investigate a new paradigm for studying the development of the colour 'signal' by having observers discriminate and categorize the same set of controlled and calibrated cardinal coloured stimuli. Notably, in both tasks, each observer was free to decide whether two pairs of colors were the same or belonged to the same category. The use of the same stimulus set for both tasks provides, we argue, an incremental behavioural measure of colour processing from detection through discrimination to categorisation. The measured data spaces are different for the two tasks, and furthermore the categorisation data is unique to each observer. In addition, we develop a model which assumes that the principal difference between the tasks is the degree of similarity between the stimuli which has different constraints for the categorisation task compared to the discrimination task. This approach not only makes sense of the current (and associated) data but links the processes of discrimination and categorisation in a novel way and, by implication, expands upon the previous research linking categorisation to other tasks not limited to colour perception.
    PLoS ONE 03/2013; 8(3):e59945. DOI:10.1371/journal.pone.0059945 · 3.23 Impact Factor
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    • "These, and many previous results (for example, Ferrera et al., 1992; Nealey and Maunsell, 1994; Leventhal et al., 1995; Vidyasagar et al., 2002; Sincich and Horton, 2005; Lee and Sun, 2009; Economides et al., 2011) challenge the notion of segregation and independence of the streams. Likewise, additional evidence (Dobkins and Albright, 1993, 1995; Gegenfurtner and Hawken, 1996; Cropper and Wuerger, 2005; Ruppertsberg et al., 2007; Martinovic et al., 2009; Wuerger et al., 2011; Poom, 2011) shows closer integration of color and motion perception than one might expect based on the parallel stream paradigm, where motion and color analysis are often cited as prime examples of the exclusive domains of the M and P streams, respectively. It appears that motion might be perceived by several mechanisms, some color-selective and others color blind (Gorea and Papathomas, 1989; Papathomas et al., 1991). "
    Edited by Jack Werner and Leo Chalupa, 01/2013: chapter 30; MIT press.
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    • "With respect to motion integration, studies on the role of contrast polarity in combining local motion signals have focused on conditions where polarity and motion direction was correlated (Edwards & Badcock, 1994; Croner & Albright, 1997; Snowden & Edmunds, 1999; Li & Kingdom, 2001; Martinovic et al., 2009; Cropper & Wuerger, 2005). In Croner and Albright (1997), a hue cue (only 10% of dots were of the same hue) was present that created a pop-out effect in the static display; when this static cue was removed (Snowden & Edmunds, 1999; Li & Kingdom, 2001), results were consistent with separate processing of local increments and decrements. "
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    ABSTRACT: Global motion integration mechanisms can utilize signals defined by purely chromatic information. Is global motion integration sensitive to the polarity of such color signals? To answer this question, we employed isoluminant random dot kinematograms (RDKs) that contain a single chromatic contrast polarity or two different polarities. Single-polarity RDKs consisted of local motion signals with either a positive or a negative S or L-M component, while in the different-polarity RDKs, half the dots had a positive S or L-M component, and the other half had a negative S or L-M component. In all RDKs, the polarity and the motion direction of the local signals were uncorrelated. Observers discriminated between 50% coherent motion and random motion, and contrast thresholds were obtained for 81% correct responses. Contrast thresholds were obtained for three different dot densities (50, 100, and 200 dots). We report two main findings: (1) dependence on dot density is similar for both contrast polarities (+S vs. -S, +LM vs. -LM) but slightly steeper for S in comparison to LM and (2) thresholds for different-polarity RDKs are significantly higher than for single-polarity RDKs, which is inconsistent with a polarity-blind integration mechanism. We conclude that early motion integration mechanisms are sensitive to the polarity of the local motion signals and do not automatically integrate information across different polarities.
    Visual Neuroscience 03/2011; 28(3):239-46. DOI:10.1017/S0952523811000058 · 2.21 Impact Factor
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