Individual Differences in Pupil Dilation during Naming Task

The present study investigates individual differences in pupil dilation during standard word naming. We looked at (i) how individual subjects’ pupil size changes over the course of time and (ii) how well pupil size is predicted by the frequency of the stimuli. The time course of the pupil size was analysed with generalized additive modeling. The results show large individual variations in the pupil response pattern in this very simple task. Although, we see a pupil response to both stimulus onset and articulation onset and offset, both the amplitude of change and the direction of change differ substantially between subjects. This raises the question of what makes the pupil response functions so diverse, and one factor indicated by the frequency effect or the lack thereof might be shallow reading versus reading for content.