August 2010
Volume 10, Issue 7
Vision Sciences Society Annual Meeting Abstract  |   August 2010
Feedback does not cleanse brightness judmements of contrast and assimilation effects
Author Affiliations
  • Steven Kies
    Department of Cognitive Sciences, UC Irvine
  • Charles Chubb
    Department of Cognitive Sciences, UC Irvine
Journal of Vision August 2010, Vol.10, 425. doi:
  • Views
  • Share
  • Tools
    • Alerts
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Steven Kies, Charles Chubb; Feedback does not cleanse brightness judmements of contrast and assimilation effects. Journal of Vision 2010;10(7):425.

      Download citation file:

      © ARVO (1962-2015); The Authors (2016-present)

  • Supplements

Judgments of the brightness of a test patch are strongly influenced by contrast and assimilation. However, the experiments that document these effects typically do not use feedback. We wondered whether observers might have access to strategies that were cleansed of these effects if they were given trial-by-trial feedback. In this study, observers viewed a 3.33° diameter Test-disk surrounded by an annular ring of what appeared to be homogenous visual noise; their task was to judge whether the luminance of the Test-disk was higher or lower than that of the fixed gray background outside the annulus. Although the annulus looked like a ring of visual noise on each trail, it was actually composed of a random, weighted sum of 11, orthogonal basis images: 5 noise images (which were constrained to contributed 94.8% of the energy in the noisy annulus and 6 concentric annuli which collectively covered the same region as each of the noise basis images and which contributed the remaining 5.2% of the energy). Data were collected for four display durations: 13, 27, 53, and 107ms. In each case, logistic regression was used to determine the influence exerted on the participant's judgments by the 11 basis components. Performance was similar for the four display durations. The innermost annulus exerted a contrast effect: Test-disk contrast judgments were negatively correlated with inner-annulus contrast. However, for four of the five participants, judgments tended to be positively correlated with the contrasts of the outermost two annuli. Plausibly, this latter effect reflects assimilation by the Test-disk of annulus brightness induced by contrast of the outer annular strip with the background. Thus the feedback supplied did not enable observers to escape contrast and assimilation effects.

Kies, S. Chubb, C. (2010). Feedback does not cleanse brightness judmements of contrast and assimilation effects [Abstract]. Journal of Vision, 10(7):425, 425a,, doi:10.1167/10.7.425. [CrossRef]
 National Science Foundation BCS-0843897.

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.