May 2008
Volume 8, Issue 6
Free
Vision Sciences Society Annual Meeting Abstract  |   May 2008
Coming to terms with lightness and brightness: effects of stimulus configuration and instructions on brightness and lightness judgments
Author Affiliations
  • Mark McCourt
    Center for Visual Neuroscience, Department of Psychology, North Dakota State University, Fargo, ND 58105
  • Barbara Blakeslee
    Center for Visual Neuroscience, Department of Psychology, North Dakota State University, Fargo, ND 58105
Journal of Vision May 2008, Vol.8, 291. doi:10.1167/8.6.291
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      Mark McCourt, Barbara Blakeslee; Coming to terms with lightness and brightness: effects of stimulus configuration and instructions on brightness and lightness judgments. Journal of Vision 2008;8(6):291. doi: 10.1167/8.6.291.

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Abstract

Depending on the experimental conditions, lightness (perceived reflectance) may refer to judgments that are identical to brightness judgments (perceived luminance), to local brightness-contrast judgments (the brightness difference between a target and its background), or that represent an independent dimension of achromatic experience (Arend & Spehar, 1993 a; b). This third dimension exists only when the illumination across regions of the display is visibly non-uniform and has been called “inferred-lightness” because it requires that the observer take account of the illuminant to make an inferential judgment of target reflectance (Blakeslee & McCourt, 2003). Because lightness judgments are based on different information under different conditions, lightness data generated in one condition may not be comparable to lightness data measured in another condition. We investigate this problem with regard to a history of data on simultaneous brightness/lightness contrast, by measuring brightness, brightness contrast and lightness in stimuli similar to those used in Gilchirst's early edge-substitution studies (Gilchrist, 1979; 1988; Gilchrist, Delman & Jacobsen, 1983). Our results clarify discrepancies in this literature which appear to stem from comparing different types of lightness judgments and from inadvertently using brightness as an index of lightness under conditions where inferred-lightness judgments are possible (Gilchrist, 1999; Gilchrist, 2006).

McCourt, M. Blakeslee, B. (2008). Coming to terms with lightness and brightness: effects of stimulus configuration and instructions on brightness and lightness judgments [Abstract]. Journal of Vision, 8(6):291, 291a, http://journalofvision.org/8/6/291/, doi:10.1167/8.6.291. [CrossRef]
Footnotes
 This work was supported by grants from the National Science Foundation (IBN-0212789), the National Eye Institute (NEI) (R01 EY014015) and the National Center for Research Resources (NCRR) (P20 RR020151).
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