Abstract: Using the reaction time as the indicator and presenting the stimuli ina tachistoscope, these experiments changed systemically the area and refle-ctance of the inducing fields. The purpose was to investigate the perceptionof subjective contours. The results showed that the subject's reaction timeincreased with the decrease of the area and the increase of the reflectan-ce of the inducing field. The difference was very significant among thereaction times. These demonstrate that the area and reflectance of the in-ducing fields cause a systematic change of the subjective contour, mediatedby brightness contrast. This suggests that the brightness contrast producedby the lateral inhibition in the visual system plays a very important rolein the perception of subjective contours.

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