Responses to Lightness Variations in Early Human Visual Cortex

Huseyin Boyaci, Fang Fang, Scott O. Murray, Daniel Kersten

Research output: Contribution to journalArticle

49 Scopus citations


Lightness is the apparent reflectance of a surface, and it depends not only on the actual luminance of the surface but also on the context in which the surface is viewed [1-10]. The cortical mechanisms of lightness processing are largely unknown, and the role of early cortical areas is still a matter of debate [11-17]. We studied the cortical responses to lightness variations in early stages of the human visual system with functional magnetic resonance imaging (fMRI) while observers were performing a demanding fixation task. The set of dynamically presented visual stimuli included the rectangular version of the classic Craik-O'Brien stimulus [3, 18, 19] and a variant that led to a weaker lightness effect, as well as a pattern with actual luminance variations. We found that the cortical activity in retinotopic areas, including the primary visual cortex (V1), is correlated with context-dependent lightness variations.

Original languageEnglish (US)
Pages (from-to)989-993
Number of pages5
JournalCurrent Biology
Issue number11
StatePublished - Jun 5 2007



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