Effects of attentional breadth and task difficulty on tonic pupil size

Ivanov, Yavor (2019) Effects of attentional breadth and task difficulty on tonic pupil size. Research Project 1 (minor thesis), Behavioural and Cognitive Neurosciences.

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Abstract

Changes in pupil size may accompany changes in perceptual needs. The present experiment investigated whether baseline pupil size is influenced by the breadth of attention, operationalized as the distance (i.e. eccentricity) from central vision at which attention is sustained. We designed a version of the attentional-breadth task (Brocher, Harbecke, Graf, Memmert, & Hüttermann, 2018) in which participants perform a visual memory task with stimuli appearing at different eccentricities. Crucially, we varied both target eccentricity and task effort independently. We expected tonic pupil size to linearly increase with the eccentricity at which participants sustain attention. This hypothesis was based on the idea that larger pupils may provide greater visual sensitivity, which would benefit the detection of stimuli appearing in peripheral vision. Furthermore, we expected tonic pupil size to increase as a function of the mental effort invested in the task, due to the hypothesized correlation between arousal and pupil size. Our results show that both target eccentricity and task difficulty had no effects on tonic pupil size, suggesting that these factors may have an effect only on the magnitude of transient pupil dynamics.

Item Type:	Thesis (Research Project 1 (minor thesis))
Supervisor name:	Mathot, S.
Degree programme:	Behavioural and Cognitive Neurosciences
Thesis type:	Research Project 1 (minor thesis)
Language:	English
Date Deposited:	13 Mar 2019
Last Modified:	22 Mar 2019 14:54
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/19263

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