Second-order stimulus
Encyclopedia
A second-order stimulus is a form of visual stimulus used in psychophysics
in which objects are delineated from their backgrounds by differences of contrast
or texture. On the contrary, a stimulus defined by differences in luminance is known as a first-order stimulus.
Psychophysics
Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they effect. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, more completely, as "the analysis of perceptual...
in which objects are delineated from their backgrounds by differences of contrast
Contrast (vision)
Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view...
or texture. On the contrary, a stimulus defined by differences in luminance is known as a first-order stimulus.