| Motion transparency from opposing luminance modulated and contrast modulated gratings. | |
| | |
MedLine Citation:
|
PMID: 19200807 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
Two luminance gratings of identical orientation and opposite directions of motion are seen as moving across one another (i.e. moving transparently) only if they differ in spatial frequency (SF) by a factor of four or more. Identical SF gratings produce counter-phase flicker. This suggests that opposite motions cancel each other at the level of motion detection. Here we show that motion transparency is perceived with two gratings of the same SF and orientation moving in opposite directions, when one grating is a first-order, luminance modulated (LM) stimulus and the other is a second-order, contrast modulated (CM) stimulus. Participants were presented with various combinations of LM and CM gratings. In experiment 1, the test stimulus contained the summation of oppositely moving LM and CM gratings. In order to assess the simultaneous perception of both motions, we used a paradigm where observers were required to discriminate the direction of motion of each component from counter-phase flicker. Results show that observers can accurately discriminate both LM and CM directions of motion in a transparent configuration. We next measured the effect of varying the contrast/modulation depth of LM and CM gratings on the perception of transparency. The perception of motion transparency depends upon the relative contrast/modulation depth of the component gratings: raising the contrast of the LM component necessitates a greater modulation depth for the CM component if motion transparency is to be perceived. Our results are consistent with a motion system comprised of two separate, but not wholly independent, pathways for the encoding of LM and CM signals. We hypothesise that the observed contrast dependence is the result of contrast gain control mechanisms that receive inputs from separate motion systems. |
| | |
Authors:
|
Ross Goutcher; Gunter Loffler |
Related Documents
:
|
9274777 - Implicit masking constrained by spatial inhomogeneities. 2585057 - Neural circuits mediating visual flight control in flies. i. quantitative comparison of... 18079947 - High-resolution spectrometry for diffuse light by use of anamorphic concentration. 3832597 - On seeing temporal gaps between gratings: a criterion problem for measurement of visibl... 14562097 - The speed of information in a 'fast-light' optical medium. 12567747 - Motion perception of short-wavelength sensitive cones in glaucoma using random dots mov... |
Publication Detail:
|
Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2009-02-05 |
Journal Detail:
|
Title: Vision research Volume: 49 ISSN: 1878-5646 ISO Abbreviation: Vision Res. Publication Date: 2009 Mar |
Date Detail:
|
Created Date: 2009-04-20 Completed Date: 2009-07-01 Revised Date: - |
Medline Journal Info:
|
Nlm Unique ID: 0417402 Medline TA: Vision Res Country: England |
Other Details:
|
Languages: eng Pagination: 660-70 Citation Subset: IM |
Affiliation:
|
Department of Psychology, University of Stirling, Stirling FK9 4LA, UK. ross.goutcher@stir.ac.uk |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Contrast Sensitivity
/
physiology* Discrimination (Psychology) Flicker Fusion / physiology Humans Male Motion Perception / physiology* Orientation Pattern Recognition, Visual / physiology* Photic Stimulation / methods Psychophysics |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Microstrabismus: Fixation point scotoma, a perimetric artefact.
Next Document: The role of invariant line junctions in object and visual word recognition.