RT Journal Article
SR Electronic
T1 Pupil size asymmetries are modulated by an interaction between attentional load and task experience
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 137893
DO 10.1101/137893
A1 Basil Wahn
A1 Daniel P. Ferris
A1 W. David Hairston
A1 Peter König
YR 2017
UL http://biorxiv.org/content/early/2017/05/15/137893.abstract
AB In a recently published study [1], we investigated how human pupil sizes are modulated by task experience as well as attentional load in a visuospatial task. In particular, participants performed a multiple object tracking (MOT) task while pupil sizes were recorded using binocular eyetracking measurements. To vary the attentional load, participants performed the MOT task either tracking zero or up to five targets. To manipulate the task experience, participants performed the MOT task on three consecutive days. We found that pupil sizes systematically increased with attentional load and decreased with additional task experience. For all these analyses, we averaged across the pupil sizes for the left and right eye. However, findings of a recent study [2] have suggested that also asymmetries in pupil sizes could be related to attentional processing. Given these findings, we further analyzed our data to investigate to what extent pupil size asymmetries are modulated by attentional load and task experience. We found a significant interaction effect between these two factors. That is, on the first day of the measurements, pupil size asymmetries were not modulated by attentional load while this was the case for the second and third day of the measurements. In particular, for the second and third day, pupil size asymmetries systematically increased with attentional load, indicating that attentional processing also modulates pupil size asymmetries. Given these results, we suggest that an increase in task experience (and associated reductions in arousal) uncover modulations in pupil size asymmetries related to attentional processing that are not observable for typical arousal levels. We suggest that these modulations could be a result of right-lateralized attentional processing in the brain that in turn influences structures involved in the control of pupil sizes such as the locus coeruleus. We can exclude a number of possible alternative explanations for this effect related to our experimental setup. Yet, given the novelty of this finding and the arguably speculative explanation of the underlying mechanisms, we suggest that future studies are needed to replicate the present effect and further investigate the underlying mechanisms.