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Expression of conditional fear with and without awareness
David C Knight1, Hanh T Nguyen, Peter A Bandettini
1Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA. knightd@mail.nih.gov
Summary
Fear conditioning can occur even without conscious awareness of the fear-eliciting stimuli. This implicit learning, measured by skin conductance response, shows that associative learning is independent of awareness in Pavlovian fear conditioning.
Area of Science:
- Cognitive Psychology
- Neuroscience
- Behavioral Science
Background:
- Pavlovian conditioning is often viewed as implicit memory.
- The role of awareness in associative learning remains debated.
- Prior studies on unconscious conditioning face methodological critiques.
Purpose of the Study:
- To investigate whether fear conditioning occurs independently of awareness.
- To examine the relationship between stimulus perception and conditioned responses.
- To assess the influence of awareness on the magnitude of fear conditioning.
Main Methods:
- Differential delay fear conditioning procedure with auditory stimuli (CS+ and CS-).
- Concurrent measurement of skin conductance response (SCR) and unconditioned stimulus (UCS) expectancy.
- Manipulation of stimulus perception by varying stimulus volume relative to perceptual threshold.
Main Results:
- Differential UCS expectancy (awareness) was present only for perceived stimuli.
- Differential SCR, indicating fear conditioning, occurred for both perceived and unperceived stimuli.
- The magnitude of conditioning was not affected by stimulus perception, despite larger SCRs for perceived stimuli.
Conclusions:
- Conditional fear responses can be expressed without conscious awareness of the fear-eliciting stimuli.
- The degree of associative learning in differential Pavlovian fear conditioning is independent of awareness.
- Implicit fear conditioning demonstrates that learning can occur outside conscious perception.