Pupil size reflects covert attention unconsciously biased toward regularities

Abstract

The brain uses statistical learning to extract information from regularities in the environment. To facilitate this process, attention is unconsciously biased towards the regularities. To investigate how attention is biased and how this learning process progresses, we monitored covert attention by using the pupillary light response. We predicted that behavioural data would show statistical learning occurred. In addition, we hypothesised that pupil size reflects unconscious attention biased toward regularities and indicates the onset and speed of the learning process over time. We conducted an experiment using sources containing temporal regularities and noisier sources of different luminance. Thereby, we biased covert attention and measured reaction time and pupil size data. We did find promising data on these hypotheses, but did not find significant results. We speculate that a shortage of usable trials and a conscious awareness of the regularities by the participants led to these results.