Brain indices of nonconscious associative learning

Author(s): Bernat, E., Bunce, S., Shevrin, H.

Journal/Book: Conscious Cogn. 1997; 6: 525 B St, Ste 1900, San Diego, CA 92101-4495. Academic Press Inc Jnl-Comp Subscriptions. 519-544.

Abstract: Using a classical conditioning technique, this study investigated whether nonconscious associative learning could be indexed by event-related brain activity (ERP). There were three phases. In a preconditioning baseline phase, pleasant and unpleasant facial schematics were presented in awareness (suprathreshold). A conditioning phase followed, in which stimuli were presented outside awareness (subthreshold, via energy masking), with an unpleasant face (CS+) linked to an aversive shack and a pleasant face (CS-) not linked to a shock. The third, postconditioning phase, involved stimulus presentations in awareness (suprathreshold). Evidence for acquisition of a conditional response was sought by comparing suprathreshold pre-and postconditioning phases, as well as in the subthreshold conditioning phase itself. For the pre-postconditioning phase analyses, significant ERP component differences differentiating CSS and CS-were observed for NI, P2, and especially P3. For the conditioning phase, significant differences were observed in the 100-400 ms. Post-stimulus region reflecting a CS+ processing negativity. Brain activity does indeed index the acquisition of a conditional response to subthreshold stimuli. Associative learning can occur outside awareness.

Note: Article Wong PS, New Sch Social Res, Dept Psychol, 65 5TH Ave, New York,NY 10003 USA

Keyword(s): CONTINGENT NEGATIVE-VARIATION; SKIN-CONDUCTANCE RESPONSES; REPEATED MEASURES DESIGNS; EVENT-RELATED POTENTIALS; SHOCK-ASSOCIATED WORDS; ELECTRODERMAL RESPONSES; AUTONOMIC RESPONSES; FACIAL EXPRESSIONS; CONDITIONED-STIMULI; MASKED STIMULI

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