Classical conditioning of analgesic and hyperalgesic pain responses without conscious awareness

Pain reduction and enhancement can be produced by means of conditioning procedures, yet the role of awareness during the acquisition stage of classical conditioning is unknown. We used psychophysical measures to establish whether conditioned analgesic and hyperalgesic responses could be acquired by...

Full description

Saved in:
Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2015-06, Vol.112 (25), p.7863-7867
Main Authors: Jensen, Karin, Irving Kirsch, Sara Odmalm, Ted J. Kaptchuk, Martin Ingvar
Format: Article
Language:English
Subjects:
Analgesia
Analgesics
Awareness
Behavior
Biological Sciences
Brain
classical conditioning
cognition
Cognitive ability
Conditioning, Classical
consciousness
Humans
Hyperalgesia
Learning
Medicin och hälsovetenskap
nocebo
pain
Pain - physiopathology
Pain management
placebo
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Pain reduction and enhancement can be produced by means of conditioning procedures, yet the role of awareness during the acquisition stage of classical conditioning is unknown. We used psychophysical measures to establish whether conditioned analgesic and hyperalgesic responses could be acquired by unseen (subliminally presented) stimuli. A 2 × 2 factorial design, including subliminal/supraliminal exposures of conditioning stimuli (CS) during acquisition/extinction, was used. Results showed significant analgesic and hyperalgesic responses ( P < 0.001), and responses were independent of CS awareness, as subliminal/supraliminal cues during acquisition/extinction led to comparable outcomes. The effect was significantly larger for hyperalgesic than analgesic responses ( P < 0.001). Results demonstrate that conscious awareness of the CS is not required during either acquisition or extinction of conditioned analgesia or hyperalgesia. Our results support the notion that nonconscious stimuli have a pervasive effect on human brain function and behavior and may affect learning of complex cognitive processes such as psychologically mediated analgesic and hyperalgesic responses. Significance It is unclear to what extent new learning can take place outside of conscious awareness. In the present study, we used psychophysical measures and classical conditioning to establish whether psychologically mediated analgesic and hyperalgesic responses could be acquired by unseen (subliminally presented) stimuli. Our study demonstrates that analgesia and hyperalgesia can be learned without conscious awareness, suggesting that higher-order cognitive processes may be affected by implicit learning mechanisms.
ISSN:0027-8424
1091-6490
1091-6490
DOI:10.1073/pnas.1504567112