ARTICLE UPDATE - A direct intracranial record of emotions evoked by subliminal words

Lionel Naccache, Raphaël Gaillard, Claude Adam, Dominique Hasboun, Stéphane Clémenceau, Michel Baulac, Stanislas Dehaene, and Laurent Cohen

PNAS, 102, 7713-7717.

A classical but still open issue in cognitive psychology concerns the depth of subliminal processing. Can the meaning of undetected words be accessed in the absence of consciousness? Subliminal priming experiments in normal subjects have revealed only small effects whose interpretation remains controversial. Here, we provide a direct demonstration of semantic access for unseen masked words. In three epileptic patients with intracranial electrodes, we recorded brain potentials from the amygdala, a neural structure that responds to fearful or threatening stimuli presented in various modalities, including written words. We show that the subliminal presentation of emotional words modulates the activity of the amygdala at a long latency (>800 ms). Our result indicates that subliminal words can trigger long-lasting cerebral processes, including semantic access to emotional valence.