How ambiguity helps to understand metaperception - Similar EEG correlates of geometry and emotion processing

Abstract

The sensory information is incomplete, noisy and to varying degrees ambiguous. The human perceptual system has to resolve this ambiguity to construct stable and reliable representations of the world. Recent EEG studies found large amplitude differences of two event-related potential components 200 and 400 ms after onset of ambiguous compared to disambiguated stimulus variants (“ERP Ambiguity Effects”). Importantly, the ERP Ambiguity Effects so far generalized over very different stimulus categories (geometry, motion, Gestalt perception) and are interpreted as correlates of metaperceptual processing. In the present study we tested whether the ERP Ambiguity Effects also occur with ambiguity at higher levels of complexity, namely with ambiguity in emotion. Thus we compared ERP contrasts between ambiguous and disambiguated variants of geometric cube stimuli (low-level ambiguity) and of emotional faces (high-level ambiguity). We used smiley faces as emotional stimuli in which ambiguity was created through the mouth curvature. Thus we had maximal experimental control over the stimulus parameter inducing either happy or sad emotions. We replicated findings of the ERP Ambiguity Effects for geometric stimuli and found very similar ERP Ambiguity Effects with the emotional smiley faces. In a control condition we verified that the smileys were perceived as faces. Conclusively, the ERP Ambiguity Effects generalize across very different stimulus categories and complexity levels of ambiguity. They may reflect high-level meta-perceptual reliability estimations of perceptual outcomes, beyond sensory details. We will discuss our results in the context of predictive coding theories and of potential relations to perceptual features in psychiatric disorders.

Acknowledgement: We thank Neurex (IdEx Strasbourg, France), DFG (KO 4764/1-1 and TE 280/8-1) and DFH (German French University) for financial support.