Salient omissions—pupil dilation in response to unexpected omissions of sound and touch

Abstract

IntroductionRecent theories describe perception as an inferential process based on internal predictive models adjusted by means of prediction violations (prediction error). To study and demonstrate predictive processing in the brain the use of unexpected stimulus omissions has been suggested as a promising approach as the evoked brain responses are uncontaminated by responses to stimuli. Here, we aimed to investigate the pupil’s response to unexpected stimulus omissions in order to better understand surprise and orienting of attention resulting from prediction violation. So far only few studies have used omission in pupillometry research and results have been inconsistent.MethodsThis study adapted an EEG paradigm that has been shown to elicit omission responses in auditory and somatosensory modalities. Healthy adults pressed a button at their own pace, which resulted in the presentation of sounds or tactile stimuli in either 88%, 50% or 0% (motor-control) of cases. Pupil size was recorded continuously and averaged to analyze the pupil dilation response associated with each condition.ResultsResults revealed that omission responses were observed in both modalities in the 88%-condition compared to motor-control. Similar pupil omission responses were observed between modalities, suggesting modality-unspecific activation of the underlying brain circuits.DiscussionIn combination with previous omission studies using EEG, the findings demonstrate predictive models in brain processing and point to the involvement of subcortical structures in the omission response. Our pupillometry approach is especially suitable to study sensory prediction in vulnerable populations within the psychiatric field.

Somatosensory omissions reveal action‐related predictive processing

“…More specifically, the oP3‐1, oP3‐2, and oP3‐3 components demonstrate latencies and topographies that are highly congruent with the stimulus‐evoked P3a (Polich, 2007 ), P3b (Verleger, 2020 ), and novelty P3 (Barry et al, 2016 ). The fact that omission responses are additionally accompanied by substantial pupil responses further supports the notion that the oP3 reflects processes similar to the stimulus‐evoked P300 (Dercksen et al, 2023 ). The P300, which is frequently observed in somatosensory studies (Bruyant et al, 1993 ; Deschrijver et al, 2016 ; Kida, Nishihira, Hatta, et al, 2004 ; Schröder et al, 2021 ), presumably reflects higher‐order processes related to attention reorienting and knowledge updating (e.g., Barry et al, 2016 ; Escera et al, 1998 ; Polich, 2007 ), task demands (Schröder et al, 2021 ), and stimulus–response link reactivation (Verleger, 2020 ), and is related to the phasic activation of the locus coeruleus‐norepinephrine‐system (Nieuwenhuis et al, 2011 ).…”

Cross-Modal Interactions Between Auditory Attention and Oculomotor Control

“…Ocular and pupil dynamics reveal a sequence of attentional processes Phasic pupil responsivity stands as a predominant metric for assessing task engagement, extensively researched compared to MS (Aston-Jones and Cohen, 2005;Bradley et al, 2008;Nassar et al, 2012;Dercksen et al, 2023). Frequently considered a proxy for instantaneous arousal, especially in response to unexpected events, it is hypothesized to reflect, at least to some extent, activity in the locus coeruleus-norepinephrine (LC-NE) system-the primary regulator of the brain's arousal state.…”