Cite as:
Einhäuser W, Stout J, Koch C, Carter O, 2008, "Pupil dilation and rivalry: a link between multistable perception and behavioural decision making" Perception 37 ECVP Abstract Supplement, page 128

Pupil dilation and rivalry: a link between multistable perception and behavioural decision making

W Einhäuser, J Stout, C Koch, O Carter

During sustained presentation of ambiguous stimuli, an individual's perception will switch between the different alternatives. In behaviour, the locus coeruleus (LC)--the brainstem nucleus responsible for releasing noradrenaline (NA)--plays a crucial role in consolidating the selection of a response and ensuring continual reassessment of available options. We hypothesized that the LC-NA system plays a similar role in selecting between perceptual alternatives. Since pupil dilation under constant illumination reflects LC activation, we recorded pupil diameter, while observers viewed 4 different rivalry stimuli. For all stimuli, pupil dilation was seen prior to the report of a perceptual transition. The relative dilation 600 ms prior to the transition correlated with the subsequent duration of perceptual stability. These effects could not be explained by eye movements or blinks, the motor response or by stimulus-driven changes in retinal input. This link between pupil dilation and perceptual switches suggests that the LC-NA complex plays the same role in perception as in behavioural selection, and that transitions in rivalry may be interpreted as perceptual decision making.
[Supported by the Swiss NSF (to WE), Darpa, NIMH (to CK), National Health and Medical Research Council, AUS (to OC)]

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