Can I trust in what I see? EEG evidence for a cognitive evaluation of perceptual constructs

Abstract

Environmental information available to our senses is incomplete and to varying degrees ambiguous. It has to be disambiguated in order to construct stable and reliable percepts. Ambiguous figures are artificial examples where perception is maximally unstable and alternates between possible interpretations. Tiny low-level changes can disambiguate an ambiguous figure and thus stabilize percepts. The present study compares ERPs evoked by ambiguous stimuli and disambiguated stimulus variants across three visual categories: geometry (Necker cube), motion (stroboscopic alternative motion stimulus, SAM) and semantics (Boring's old/young woman). We found that (a) disambiguated stimulus variants cause stable percepts and evoke two huge positive ERP excursions (Cohen's effect sizes 1-2), (b) the amplitudes of these ERP effects are inversely related to the degree of stimulus ambiguity, and (c) this pattern of results is consistent across all three tested visual categories. This generality across visual categories points to mechanisms at a very abstract (cognitive) level of processing. We discuss our results in the context of a high-level Bayesian inference unit that evaluates the reliability of perceptual processing results, given a priori incomplete, ambiguous sensory information. The ERP components may reflect the outcome of this reliability estimation.

Positive and negative hysteresis effects for the perception of geometric and emotional ambiguities

“…In line with these views, recent evidence from our studies indicates that some steps in the neural processing of sensory ambiguity occur at a very abstract level and are generalized across visual categories [ 52 , 53 ]. However, it is still unclear whether and how lower-level ambiguities of classical and artificial ambiguous figures are related to ambiguities at the higher level of emotional face contents.…”

“…The reaction times are in a range expected from previous studies (e.g. [ 109 , 52 ]). A common pattern found in both stimulus categories is the longer reaction times for the first stimuli in the ordered stimulus presentation conditions compared to the last, even though the perceptions for both the first and the last stimuli reach 100% probabilities, thus stable percepts.…”

“…In fact, theoretical approaches regard the perception of ambiguous figures as a low-level model of a cognitive decision process in higher-level planning and/or executive cognitive modules (e.g., [ 18 , 47 – 49 ]). Furthermore, our recent electrophysiological evidence indicates general properties of perceptual disambiguation beyond visual categories [ 52 , 53 ].…”

Perception of the difference between past and present stimulus: A rare orientation illusion may indicate incidental access to prediction error-like signals

“…The underlying neuronal difference signals may penetrate perception through post-perceptual decision, occasionally ignoring information about the actually present stimulus at higher hierarchy levels. Thus, our results may support the view that perception depends on late decision stages [31][32][33][34] at which multiple signals of recent stimulus history [31] are analyzed and integrated before reaching conscious awareness [35][36][37][38].…”

Mona Lisa is always happy – and only sometimes sad

“…Examples for such perceptual instabilities, resulting from ambiguous sensory input, exist at different levels of complexity, like low-level geometry (Necker Cube), figure-ground ambiguity (Rubin’s Vase-Face stimulus3), motion (e.g. von Schiller’s Stroboscopic Alternative Motion stimulus, “SAM”45), and also at more complex semantic levels (e.g., Boring’s Old/Young woman67). Ambiguity even exists in other modalities like audition and touch8.…”