Document Detail


Expression of conditional fear with and without awareness.
MedLine Citation:
PMID:  14657356     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Conditional responding during simple Pavlovian conditioning is often characterized as a form of implicit memory. The extent to which this type of associative learning is independent of awareness is an issue of continuing debate. Previous studies have demonstrated conditioning in the absence of awareness. However, their results have been questioned based on methodological concerns with postexperimental questionnaires. In the present study, skin conductance response (SCR) and unconditioned stimulus (UCS) expectancy were measured concurrently as participants were exposed to a differential delay fear conditioning procedure in which one tone (CS+) predicted a loud white noise, whereas a second tone (CS-) was presented alone. UCS predictability was varied on a trial-by-trial basis by presenting conditioned stimuli (CSs) at volumes just above or below the perceptual threshold. Differential UCS expectancy (awareness) was observed only on perceived trials, whereas differential SCR developed on both perceived and unperceived trials. Although perceived stimuli elicited larger SCRs, the magnitude of conditioning, indexed by differential conditioned response expression (conditioned SCR to CS+ minus the SCR to CS-), was not influenced by stimulus perception. These data indicate that conditional fear can be expressed when individuals are unaware of fear-eliciting stimuli and suggest that the degree of conditioning is independent of awareness during differential Pavlovian fear conditioning.
Authors:
David C Knight; Hanh T Nguyen; Peter A Bandettini
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.     Date:  2003-12-01
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  100     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2003 Dec 
Date Detail:
Created Date:  2003-12-10     Completed Date:  2004-01-23     Revised Date:  2010-09-21    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  15280-3     Citation Subset:  IM    
Affiliation:
Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA. knightd@mail.nih.gov
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MeSH Terms
Descriptor/Qualifier:
Adult
Awareness*
Conditioning, Classical*
Fear*
Female
Galvanic Skin Response
Humans
Male
Memory
Middle Aged
Neurons / physiology
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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