metacontrast

met·a·con·trast

(met'ă-kon'trast),
Inhibition of the brightness of illumination when an adjacent visual field is illuminated.

metacontrast

This is an apparently paradoxical phenomenon because it consists of a reduction in subjective brightness of a flash of light which is caused by a second flash following shortly afterward in an adjacent region of the visual field. The effect depends upon the duration, intensity, surface areas of the two flashes, the retinal area stimulated, and particularly the interval of time between the two flashes. The phenomenon appears most clearly with an interval of about 0.1s and disappears when that interval reaches 0.3-0.4s. Syn. backward masking (this term is used to indicate when the test stimulus and the masking stimulus overlap spatially). A flash of light can also be made to appear slightly less bright when it is preceded by another flash in an adjacent region of the visual field and the interval of time is of the order of 0.05s. This second phenomenon is called paracontrast. Syn. forward masking (this term is used when the test stimulus and the masking stimulus overlap spatially). See masking.
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More contemporary iterations of SIT refer to this process as the metacontrast principle, which functions to "maximize the ratio of perceived intergroup differences to intra-group differences and thus accentuates similarities within groups and differences between groups" (Hogg, 2006, p.
In the case of SIT, it is expected that intergroup contact, by way of a discussion, would serve to augment group differences based on the metacontrast principle and the need for positive distinctiveness.
Matin, "Metacontrast and saccadic suppression," Science, vol.
Sensitivity and perceptual awareness increase with practice in metacontrast masking.
Metacontrast masking and the cortical representation of surface color: Dynamical aspects of edge integration and contrast gain control.
Metacontrast making between cyclopean and luminance stimuli.