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A Dynamic View on Conscious and Unconscious Processes

Final Report Summary - DYNAMIND (A Dynamic View on Conscious and Unconscious Processes)

Distinguishing between conscious and unconscious processes is a fundamental issue for our understanding of the human mind. Most research on this topic has been limited to a static perspective, by studying static stimuli, by considering processing solely as a function of present information, and by focusing on a single, adult stage of development. Yet, both conscious and unconscious mental processes are intrinsically driven by dynamic properties. The DynaMind project addresses these properties by relying on behavioral and brain imaging methods in order to address 3 main objectives: 1) studying dynamic unconscious streams 2) studying the dynamic Bayesian processes by which past knowledge leads to the reconstruction of perceptual contents during partial awareness and 3) studying the dynamics of the maturation of consciousness in infants.

For objective 1, we developed the methods of “Gaze-Contingent Crowding”, which allows for the instantaneous substitution of a crowded and peripheral stimulus with an irrelevant content as soon as the observer’s attempts to focus on it, rendering the stimulus both perceptually unreachable and constantly present at the same time. This method allowed revealing for the first time the cognitive and neural processes associated with dynamic subliminal stimuli such as the nonconscious emotional processing of video contents or the instrumental learning of complex sequences of symbols.

For objective 2, we studied how prior information, in the form of decision and perceptual biases, can influences the processing of visual objects in the environment. We show that neural activity in the visual cortex preceding a degraded stimulus can predict whether an hallucination will occur. In addition, we show that the use of prior information is done in the absence of awareness, while the update of these priors involves conscious mechanisms, untangling the link between predictions and consciousness.

For objective 3, we showed that infants as young as 5 months of age have the same, albeit much slower, mechanisms of conscious access as adults, using here neural markers of consciousness in the impossibility of relying on verbal report of subjective experience in babies. We also showed that neural responses in the infant visual cortex are driven both by attentional states and prior expectations. In particular, we show that the neural markers of consciousness are triggered whenever infants face an unexpected situation, buttressing the link between surprise/novelty detection and consciousness.

In sum, by taking a dynamic view on the nature of conscious and unconscious processes, we provide new insights revealing complex processing for unconscious streams of information, untangling the link between predictions and consciousness, and showing that the neural mechanisms of consciousness can be evidenced relatively early in human life.