Eye pupil signals information gain

Abstract

In conditions of constant illumination, the eye pupil diameter indexes the modulation of arousal state and responds to a large breadth of cognitive processes, including mental effort, attention, surprise, decision processes, decision biases, value beliefs, uncertainty, volatility, exploitation/exploration trade-off, or learning rate. Here, I propose an information theoretic framework that has the potential to explain the ensemble of these findings as reflecting pupillary response to information processing. In short, updates of the brain’s internal model, quantified formally as the Kullback–Leibler (KL) divergence between prior and posterior beliefs, would be the common denominator to all these instances of pupillary dilation to cognition. I show that stimulus presentation leads to pupillary response that is proportional to the amount of information the stimulus carries about itself and to the quantity of information it provides about other task variables. In the context of decision making, pupil dilation in relation to uncertainty is explained by the wandering of the evidence accumulation process, leading to large summed KL divergences. Finally, pupillary response to mental effort and variations in tonic pupil size are also formalized in terms of information theory. On the basis of this framework, I compare pupillary data from past studies to simple information-theoretic simulations of task designs and show good correspondance with data across studies. The present framework has the potential to unify the large set of results reported on pupillary dilation to cognition and to provide a theory to guide future research.

Pupil-based states of brain integration across cognitive states

“…learning vs. task solving, exploration vs. exploitation, focused attention vs. mind wandering, etc.). In sum, our findings are consistent with theories of arousal-related neuromodulatory systems that propose their engagement in modulating neural processes in an adaptive manner Zénon, 2019).…”

The modulation of brain network integration and arousal during exploration

“…This conclusion must be qualified, however, by the relatively weak sensitivity of subject behavior to volatility level. Given that the pupillary response has been shown to be modulated by probabilities and at least qualitatively demonstrates more extended responses to low probability events ( Alamia et al, 2019 ; Qiyuan et al, 1985 ; Zénon, 2019 ), we cannot completely rule out this possibility. Nor can we rule out the possibility that the difference between explore and exploit response was due to anticipated outcome, which prior studies have demonstrated positively modulates pupil diameter ( Cash-Padgett et al, 2018 ; Van Slooten et al, 2018 ; Varazzani et al, 2015 ).…”

“…Despite this, open questions remain about the nature of the relationship. Pupil diameter is sensitive to several non-luminance-mediated factors, including uncertainty and surprise ( Alamia et al, 2019 ; Friedman et al, 1973 ; Jepma and Nieuwenhuis, 2011 ; Lavín et al, 2014 ; Nassar et al, 2012 ; Preuschoff, 2011 ; Qiyuan et al, 1985 ; Urai et al, 2017 ; Zénon, 2019 ), as well as mental load or task difficulty ( Alnæs et al, 2014 ; Hess and Polt, 1964 ; Kahneman and Beatty, 1966 ; Wahn et al, 2016 ). Notably, past task designs used to test the relationship between LC-NE-linked activity and exploratory state do not always clearly differentiate states of exploration from these other factors.…”

Magic, Bayes and wows: A Bayesian account of magic tricks

“…This latter approach seems specially promising in view that only a handful of studies investigated the physiological effect of magic (Parris et al, 2009;Danek et al, 2015;Caffaratti et al, 2016). Crucially, a number of physiological signatures have been already related specifically to Bayesian surprise, such as pupil dilation (Zénon, 2019), the P300 evoked related potential in EEG (Mars et al, 2008;Wacongne et al, 2011;Kolossa et al, 2012;Kopp et al, 2016) and fMRI responses in the dorsal anterior cingulate cortex (Ide et al, 2013;O'Reilly et al, 2013;Schwartenbeck et al, 2016). This previous empirical work and theoretical framework allows a variety of hypothesis-driven physiological studies of magic tricks, such as the parametric modulation of neural signals as a function of surprise, contextual information and attentional control.…”