Kanizsa-like illusory figures shorten simple manual reaction time

The present study provides evidence that simple manual reaction time (RT) can be shortened by task irrelevant Kanizsa-like illusory figures emerging as completed perceptual units in the observer's visual system. This type of behavioral effect allows to evaluate the role of a perceived figure constituted by brightness enhancement, illusory contours and depth stratification by maintaining constant retinal size and average luminance of the inducers in modulating RT. Using two different versions of the inducers, with the same retinal size and different average luminance, we found that simple RT was shortened by the presence vs absence of the figure with significant faster response in the illusory condition than no-illusory condition in the two versions of the inducers. These results confirm previous works that provide evidence on the relationship between simple RT and perceptual/phenomenal features.