Format

Send to

Choose Destination
Vision Res. 2007 Sep;47(21):2700-13. Epub 2007 Sep 6.

Defining the detection mechanisms for symmetric and rectified flicker stimuli.

Author information

1
Department of Optometry and Vision Sciences, The University of Melbourne, VIC, Australia.

Abstract

Symmetric flicker modulates about a background light level and effects no change in the time-average luminance. Rectified flicker is achieved by modulating a luminance-increment and results in both a flickering component and an increase in the time-averaged luminance (luminance-pedestal) above the adapting background light level. We studied the effect that changes in adapting light level and local luminance (within the area of the flickering target) have on thresholds. We measured thresholds for single and multiple cycles of flicker over a range of adapting light levels (Threshold versus Intensity paradigm) and defined their gain as a function of luminance-pedestal amplitude (Threshold versus Amplitude paradigm). The dynamics of symmetric and rectified flicker responses were determined using a Stimulus Onset Asynchrony paradigm. The data show rectified flicker thresholds differ from symmetric flicker thresholds due to two factors that can be contrast-dependent or contrast-independent: (1) local adaptation, which varies with stimulus duration and (2) surround interactions that depend on adapting light level. The dynamics of the thresholds for symmetric and rectified flicker stimuli suggest the detection mechanisms occur early in the visual pathways, involving the magnocellular pathway.

PMID:
17825346
DOI:
10.1016/j.visres.2007.05.005
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center