Article

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.

Download full-text

Full-text

Available from: Sophie M Wuerger, Jul 01, 2015
0 Followers
 · 
90 Views
  • Source
    Edited by Jack Werner and Leo Chalupa, 01/2013: chapter 30; MIT press.
  • Source
    [Show abstract] [Hide abstract]
    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 · 1.68 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A moving edge or contrast between equiluminant colours produces a weaker motion percept than that defined by luminance contrast. However, the specific contrasts that determine chromatic motion have not been explored systematically. Here, rivalrous chromatic motion displays were produced by superimposing two gratings, one drifting from left to right and the other in the opposite direction. Each grating oscillated between equiluminant endpoints chosen from a pool of 16 colours. The rivalrous ambiguity resolved spontaneously for each display as the more-dissimilar colour pair dominated the less-dissimilar pair, and produced a percept of motion in the corresponding direction. These dissimilarity judgements were analysed with multidimensional scaling to represent 'motion salience' as distances in a colour map, to gauge whether chromatic motion is enhanced or weakened if the oscillation aligns with particular directions in the colour plane. Judgements were compared with other control judgements involving standard subjective dissimilarities between the same stimuli. Notably, chromatic motion was strongest when grating endpoints were separated along an orange-blue direction. This does not coincide with either cardinal axis of cone space, (L-M) or S(0) , but rather is a direction that would arise if motion is computed from a combination of the (L-M) and S(0) signals.
    Ophthalmic and Physiological Optics 09/2010; 30(5):578-82. DOI:10.1111/j.1475-1313.2010.00738.x · 2.66 Impact Factor