Cortical processing of a brightness illusion

Anna Wang Roe, Haidong D. Lu, Chou P. Hung

Research output: Contribution to journalArticlepeer-review

95 Scopus citations


Several brightness illusions indicate that borders can affect the perception of surfaces dramatically. In the Cornsweet illusion, two equiluminant surfaces appear to be different in brightness because of the contrast border between them. Here, we report the existence of cells in monkey visual cortex that respond to such an "illusory" brightness. We find that luminance responsive cells are located in color-activated regions (cytochrome oxidase blobs and bridges) of primary visual cortex (V1), whereas Cornsweet responsive cells are found preferentially in the color-activated regions (thin stripes) of second visual area (V2). This colocalization of brightness and color processing within V1 and V2 suggests a segregation of contour and surface processing in early visual pathways and a hierarchy of brightness information processing from V1 to V2 in monkeys.

Original languageEnglish (US)
Pages (from-to)3869-3874
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number10
StatePublished - Mar 8 2005
Externally publishedYes


  • Cornsweet
  • Optical imaging
  • Thin stripes

ASJC Scopus subject areas

  • General


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