Covert attention affects the psychometric function of contrast sensitivity

E. Leslie Cameron, Joanna C. Tai, Marisa Carrasco

Research output: Contribution to journalArticlepeer-review


We examined the effect of transient covert attention on the psychometric function for contrast sensitivity in an orientation discrimination task when the target was presented alone in the absence of distracters and visual masks. Transient covert attention decreased both the threshold (consistent with a contrast gain mechanism) and, less consistently, the slope of the psychometric function. We assessed performance at 8 equidistant locations (4.5° eccentricity) and found that threshold and slope depended on target location - both were higher on the vertical than the horizontal meridian, particularly directly above fixation. All effects were robust across a range of spatial frequencies, and the visual field asymmetries increased with spatial frequency. Notwithstanding the dependence of the psychometric function on target location, attention improved performance to a similar extent across the visual field. Given that, in this study, we excluded all sources of external noise, and that we showed experimentally that spatial uncertainty cannot explain the present results, we conclude that the observed attentional benefit is consistent with signal enhancement.

Original languageEnglish (US)
Pages (from-to)949-967
Number of pages19
JournalVision research
Issue number8
StatePublished - 2002


  • Asymmetry
  • Discrimination
  • Performance fields
  • Spatial frequency
  • Transient covert attention

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems


Dive into the research topics of 'Covert attention affects the psychometric function of contrast sensitivity'. Together they form a unique fingerprint.

Cite this