although the psychophysiological adjustments of the eye pupil to illusory patterns may seem useless, 

according to this perspective, these changes in diameter could be more adaptive 

than pupil responses based on a more precise scaling of the physical features of visual stimuli. 

specifically, a preparatory constriction to illusory light could 

have an important function by promoting behavior to avoid 

being “dazzled” by physical (real) light. 

in fact, glare can temporarily incapacitate sight and lead to life-threatening situations (e.g., it is a common cause of lethal traffic accidents.

frontiers

the eye pupil adjusts to illusory expanding holes