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Sarina H.L. Chien, Kevin W. Bronson-Castain; Lightness constancy in 4-month-old infants: The effect of background reflectance. Journal of Vision 2002;2(7):368. doi: 10.1167/2.7.368.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose. Chien at al. (ARVO 2001) reported that, tested with grey stimuli against a homogeneous white background field, 4-month-old infants exhibit adult-like simultaneous lightness contrast. By manipulating the background reflectance, our present goal is to test whether infants exhibit lightness constancy when either the anchoring cue or the local luminance ratio cue provided by the white background is absent.
Methods. The forced-choice familiarization method (Chien et al, ARVO 2001) is being used to measure infants' novelty responses. The apparatus is a 24″*30″*24″ (L*H*D) testing chamber with a front 12″*12″ open window for infants to view the stimuli. The stimuli are real paper surfaces of different reflectance (64% (light grey) and 23.5% (dark grey)) and are patterned as square smiley faces. The background reflectance is either 90% (white) in the full cue experiment, or 5% (black) in the dark-background experiment. Two incandescent illumination levels differing by about a factor of 3 are being used. In the familiarization phase of each trial, infants are exposed to two identical smiley faces under one illumination. In the test phase, the illumination is either increased or decreased by about a factor of 3. The infant is presented one smiley face that has the same reflectance but with a novel luminance and another smiley face with a novel reflectance but the same luminance. If infants have lightness constancy, they are expected to prefer the face with a novel reflectance regardless of changes in illumination.
Results. In the full cue experiment, infants (n=10) showed significant novelty responses to the face with a novel reflectance, regardless of changes in illumination. This behavior indicates that the reflectance-matched face is seen as familiar across changes in illumination, indicating the presence of lightness constancy when both an anchoring cue and a luminance ratio cue are present. Data collection on the reduced-cue experiment is in progress.
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