Area summation of first- and second-order modulations of luminance

Summers, Robert J., Baker, Daniel H. and Meese, Tim S. (2015). Area summation of first- and second-order modulations of luminance. Journal of Vision, 15 (1),

Abstract

To extend our understanding of the early visual hierarchy, we investigated the long-range integration of first- and second-order signals in spatial vision. In our first experiment we performed a conventional area summation experiment where we varied the diameter of (a) luminance-modulated (LM) noise and (b) contrastmodulated (CM) noise. Results from the LM condition replicated previous findings with sine-wave gratings in the absence of noise, consistent with long-range integration of signal contrast over space. For CM, the summation function was much shallower than for LM suggesting, at first glance, that the signal integration process was spatially less extensive than for LM. However, an alternative possibility was that the high spatial frequency noise carrier for the CM signal was attenuated by peripheral retina (or cortex), thereby impeding our ability to observe area summation of CM in the conventional way. To test this, we developed the ''Swiss cheese'' stimulus of Meese and Summers (2007) in which signal area can be varied without changing the stimulus diameter, providing some protection against inhomogeneity of the retinal field. Using this technique and a two-component subthreshold summation paradigm we found that (a) CM is spatially integrated over at least five stimulus cycles (possibly more), (b) spatial integration follows square-law signal transduction for both LM and CM and (c) the summing device integrates over spatially-interdigitated LM and CM signals when they are co-oriented, but not when crossoriented. The spatial pooling mechanism that we have identified would be a good candidate component for amodule involved in representing visual textures, including their spatial extent.

Publication DOI: https://doi.org/10.1167/15.1.12
Divisions: Life & Health Sciences > Optometry
Life & Health Sciences
Additional Information: © 2015 ARVO Funding: EPSRC (EP/H000038/1)
Uncontrolled Keywords: area summation,computational modeling,cue combination,second order,Ophthalmology,Sensory Systems
Full Text Link:
Related URLs: http://www.scopus.com/inward/record.url?scp=85017330452&partnerID=8YFLogxK (Scopus URL)
http://jov.arvojournals.org/article.aspx?articleid=2213204 (Publisher URL)
Published Date: 2015-01-14
Authors: Summers, Robert J. ( 0000-0003-4857-7354)
Baker, Daniel H.
Meese, Tim S. ( 0000-0003-3744-4679)

Download

[img]

Version: Published Version

| Preview

Export / Share Citation


Statistics

Additional statistics for this record