The pupillary light response reflects eye-movement preparation

Area of Science:

• Neuroscience
• Ophthalmology
• Cognitive Science

Background:

• The pupillary light response (PLR) is traditionally considered a reflexive action to light.
• It was previously believed that cognitive factors do not influence the PLR.

Purpose of the Study:

• To investigate whether the pupillary light response (PLR) is influenced by cognitive preparation before eye movements.
• To explore the relationship between pupillary responses, attention, and eye movement preparation.

Main Methods:

• Participants performed saccadic eye movements toward peripheral targets.
• Gaze-contingent display changes manipulated target background brightness during saccade preparation.
• This design dissociated preparatory PLR from the regular PLR.

Main Results:

• A preparatory pupillary response occurred before the eyes landed on the target.
• The pupil adjusted in anticipation of the target's brightness.
• This preparatory response was linked to the presaccadic shift of attention.

Conclusions:

• The PLR is not purely reflexive and is influenced by cognitive preparation.
• Pupil size adjusts in anticipation of a to-be-fixated stimulus's brightness.
• The PLR is dynamically linked to visual attention and eye movement preparation.