Dynamic interactions between top-down expectations and conscious awareness

Abstract

It is well known that top-down expectations affect perceptual processes. Yet, remarkably little is known about the relationship between expectations and conscious awareness We address three crucial questions that are outstanding: 1) How do predictions affect the likelihood of conscious stimulus perception?; 2) Does the brain register violations of predictions nonconsciously?; and 3) Do predictions need to be conscious to influence perceptual decisions? We performed three experiments in which we manipulated stimulus predictability within the attentional blink paradigm, while combining visual psychophysics with electrophysiological recordings. We found that valid stimulus expectations increase the likelihood of conscious access of stimuli. Furthermore, our findings suggest a clear dissociation in the interaction between expectations and consciousness: conscious awareness seems crucial for the implementation of top-down predictions, but not for the bottom-up generation of stimulus-evoked prediction errors. These results constrain and update influential theories about the role of consciousness in the predictive brain.. CC-BY-NC-ND 4.0 International license not peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/151019 doi: bioRxiv preprint first posted online Jun. 16, 2017; 3 A rapidly growing body of work indicates that sensory processing is strongly influenced by the expectations that we have about likely states of the world. Such expectations are shaped by the immediate environment or context in which we are operating, but also by learning, past experience and our genetic makeup [1][2][3] .Expectations are typically thought to originate from higher-level brain regions, such as the prefrontal cortex, which may guide information processing in lower-level sensory regions via top-down (descending) projections 4,5 . In this framework, what we consciously see is proposed to be strongly influenced by the brain's expectations about, or its best guess of, the outside world 6,7 . Initial studies support a tight relationship between expectations and conscious perception. For example, it has been shown that objects that are unexpected in a particular visual scene (e.g. a hammer in the kitchen) are detected more slowly than expected objects (e.g. a knife in the kitchen) 8 . Further, a correct prediction about the nature of an upcoming stimulus (e.g. the orientation of a Gabor) improves its discrimination 9 and sharpens its neural representation 10. The brain can thus use predictive information in the environment to build expectations of stimulus frequency or conditional probabilities to modify subsequent sensory information processing and perception. These ideas have been formalized in several theoretical models, such as predictive coding and sequential sampling models 3,11,12 . Although these frameworks are attractive in their simplicity and are rapidly growing in scientific stature, how exactly predictions shape conscious ...

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