Document Detail


Contrast gain control in first- and second-order motion perception.
MedLine Citation:
PMID:  8972586     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A novel pedestal-plus-test paradigm is used to determine the nonlinear gain-control properties of the first-order (luminance) and the second-order (texture-contrast) motion systems, that is, how these systems' responses to motion stimuli are reduced by pedestals and other masking stimuli. Motion-direction thresholds were measured for test stimuli consisting of drifting luminance and texture-contrast-modulation stimuli superimposed on pedestals of various amplitudes. (A pedestal is a static sine-wave grating of the same type and same spatial frequency as the moving test grating.) It was found that first-order motion-direction thresholds are unaffected by small pedestals, but at pedestal contrasts above 1-2% (5-10 x pedestal threshold), motion thresholds increase proportionally to pedestal amplitude (a Weber law). For first-order stimuli, pedestal masking is specific to the spatial frequency of the test. On the other hand, motion-direction thresholds for texture-contrast stimuli are independent of pedestal amplitude (no gain control whatever) throughout the accessible pedestal amplitude range (from 0 to 40%). However, when baseline carrier contrast increases (with constant pedestal modulation amplitude), motion thresholds increase, showing that gain control in second-order motion is determined not by the modulator (as in first-order motion) but by the carrier. Note that baseline contrast of the carrier is inherently independent of spatial frequency of the modulator. The drastically different gain-control properties of the two motion systems and prior observations of motion masking and motion saturation are all encompassed in a functional theory. The stimulus inputs to both first- and second-order motion process are normalized by feedforward, shunting gain control. The different properties arise because the modulator is used to control the first-order gain and the carrier is used to control the second-order gain.
Authors:
Z L Lu; G Sperling
Related Documents :
15597046 - Exploring the role of visual perceptual grouping on the audiovisual integration of motion.
16772896 - The effects of optical blur on motion and texture perception.
20377286 - A set of high-order spatiotemporal stimuli that elicit motion and reverse-phi percepts.
3806436 - Motion detection in the presence and absence of background motion in an anolis lizard.
19787606 - Macular pigment optical density relates to foveal thickness.
1212486 - Within mode quality and intensity changes of habituated stimuli.
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of the Optical Society of America. A, Optics, image science, and vision     Volume:  13     ISSN:  1084-7529     ISO Abbreviation:  J Opt Soc Am A Opt Image Sci Vis     Publication Date:  1996 Dec 
Date Detail:
Created Date:  1997-01-07     Completed Date:  1997-01-07     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9800943     Medline TA:  J Opt Soc Am A Opt Image Sci Vis     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2305-18     Citation Subset:  IM; S    
Affiliation:
Department of Psychology, University of Southern California, Los Angeles 90089, USA.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Contrast Sensitivity / physiology*
Humans
Male
Motion Perception / physiology*
Sensory Thresholds
Vision, Ocular / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Inhibition of mouse egg chromosome decondensation due to meiotic apparatus derangement induced by th...
Next Document:  Cone-rod receptor spaces with illustrations that use CRT phosphor and light-emitting-diode spectra.