The present study investigates individual differences in pupildilation during standard word naming. We looked at (i) howindividual subjects’ pupil size changes over the course of timeand (ii) how well pupil size is predicted by the frequency ofthe stimuli. The time course of the pupil size was analysedwith generalized additive modeling. The results show large in-dividual variations in the pupil response pattern in this verysimple task. Although, we see a pupil response to both stimu-lus onset and articulation onset and offset, both the amplitudeof change and the direction of change differ substantially be-tween subjects. This raises the question of what makes thepupil response functions so diverse, and one factor indicatedby the frequency effect or the lack thereof might be shallowreading versus reading for content.