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Pupil dilation reveals top–down attentional load during spatial monitoring

Lisi, M., Bonato, M. and Zorzi, M. (2015). Pupil dilation reveals top–down attentional load during spatial monitoring. Biological Psychology, 112, pp. 39-45. doi: 10.1016/j.biopsycho.2015.10.002

Abstract

It has long been known that the diameter of human pupil enlarges with increasing effort during the execution of a task. This has been observed not only for purely mechanical effort but also for mental effort, as for example the computation of arithmetic problems with different levels of difficulty. Here we show that pupil dilation reflects changes in visuospatial awareness induced by attentional load during multi-tasking. In the single-task condition, participants had to report the position of lateralized, briefly presented, masked visual targets ("right", "left", or "both" sides). In the multitasking conditions, participants also performed additional tasks, either visual or auditory, to increase the attentional load. Sensory stimulation was kept constant across all conditions to rule out the influence of low-level factors. Results show that event-related pupil dilation strikingly increased with task demands, mirroring a concurrent decrease in visuospatial awareness. Importantly, pupil dilation significantly differed between two dual-task conditions that required to process the same number of stimuli but yielded differed levels of accuracy (difficulty). In contrast, pupil dilation did not differ between two conditions which were equally challenging but differed both in the modality of the dual task (auditory vs. visual) and in the number of stimuli to be attended. We conclude that pupil dilation genuinely reflects the top-down allocation of supramodal attentional resources.

Publication Type: Article
Additional Information: © 2015, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Publisher Keywords: Attention, Pupil dilation, Attentional load, Spatial awareness
Subjects: B Philosophy. Psychology. Religion > BF Psychology
R Medicine > RE Ophthalmology
Departments: School of Health Sciences > Optometry & Visual Science
URI: http://openaccess.city.ac.uk/id/eprint/17625
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