ABSTRACTPerceptual load is reflected in the size of the eye pupil. High perceptual load decreases processing of irrelevant information because attentional resources are employed in the experimental task. Large scale attentional zoom decreases processing efficiency due to a spread of attentional resources. The relationship between perceptual load, attentional zoom, and distractor processing was investigated with modified version of Beck and Lavie’s (2005) distractor processing paradigm. Both behavioural data (i.e. accuracy and response times) and a physiological measure (pupil change) were recorded concomitantly. Results indicated that pupils dilated more in the high load conditions than in the low load conditions, but failed to show differences due to display size manipulations. Moreover, while behavioural data indicated that distractor processing was reduced in the high load condition, pupil reactions to different distractors were just as strong in both the high and the low load condition. It is argued that the pupil is highly sensitive to fluctuations in effort.