Imaging unconscious semantic priming.
Visual words that are masked and presented so briefly that they cannot be seen may nevertheless facilitate the subsequent processing of related words, a phenomenon called masked priming. It has been debated whether masked primes can activate cognitive processes without gaining access to consciousness. Here we use a combination of behavioural and brain-imaging techniques to estimate the depth of processing of masked numerical primes. Our results indicate that masked stimuli have a measurable influence on electrical and haemodynamic measures of brain activity. When subjects engage in an overt semantic comparison task with a clearly visible target numeral, measures of covert motor activity indicate that they also unconsciously apply the task instructions to an unseen masked numeral. A stream of perceptual, semantic and motor processes can therefore occur without awareness.
INSERM U.334, Service Hospitalier Frédéric Joliot, CEA/DRM/DSV, Orsay, France. dehaene@shfj.cea.fr
S
S
Dehaene
L
L
Naccache
G
G
Le Clec'H
E
E
Koechlin
M
M
Mueller
G
G
Dehaene-Lambertz
P F
PF
van de Moortele
D
D
Le Bihan
D000328:Adult; D003071:Cognition; D005071:Evoked Potentials; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011932:Reading; D013360:Subliminal Stimulation; D014473:Unconscious, Psychology; D014796:Visual Perception / Q000502:physiology*