Conscious and unconscious expectancy effects: A behavioral, scalp and intracranial electroencephalography study

• Published in: Clinical neurophysiology 2020-02, Vol.131 (2), p.385-400
• Main Authors: Rozier, Camille, Seidel Malkinson, Tal, Hasboun, Dominique, Baulac, Michel, Adam, Claude, Lehongre, Katia, Clémenceau, Stéphane, Navarro, Vincent, Naccache, Lionel
• Format: Article
• Language: English
• Subjects: Behavior; Consciousness; Contingent negative variation; EEG; iEEG; Life Sciences; Subliminal; Temporal attention; Visual masking
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/j.clinph.2019.10.024

•Both supraliminal and subliminal cues can affect response times and modulate brain activity.•Supraliminal CNV originates from temporal and mesio-frontal (Supplementary Motor Areas) neural sources.•Subliminal CNV originates from temporal lobe sources. The scope of unconscious cognition stretched its limits dramatically during the last 40 years, yet most unconscious processes and representations that have been described so far are fleeting and very short-lived, whereas conscious representations can be actively maintained in working memory for a virtually unlimited period. In the present work we aimed at exploring conscious and unconscious lasting (>1 second) expectancy effects. In a series of four experiments we engaged participants in the foreperiod paradigm while using both unmasked and masked cues that were informative about the presence/absence of an upcoming target. We recorded behavioral responses, high-density scalp EEG (Exp. 2a), and intra-cranial EEG (Exp. 2b). While conscious expectancy was associated with a large behavioral effect (~150 ms), unconscious expectancy effect was significant but much smaller (4 ms). Both conscious and unconscious expectancy Contingent Negative Variations (CNVs) originated from temporal cortices, but only the late component of conscious CNV originated from an additional source located in the vicinity of mesio-frontal areas and supplementary motor areas. Finally, only conscious expectancy was accessible to introspection. Both unmasked and masked cues had an impact on response times and on brain activity. These results support a two-stage model of the underlying mechanisms of expectancy.