Startle modulation and explicit valence evaluations dissociate during backward fear conditioning.

Area of Science:

• Psychology
• Neuroscience
• Cognitive Science

Background:

• Affective stimuli modulate blink startle magnitude, with pleasant stimuli inhibiting and unpleasant stimuli potentiating startle responses.
• A previous study reported a dissociation between startle modulation and explicit valence in backward conditioning, where conditioned stimuli (CS) were implicitly positive but explicitly negative.

Purpose of the Study:

• To replicate the dissociation between startle modulation and explicit valence evaluations in backward conditioning using a trial-by-trial measure.
• To investigate if early and late portions of the CS acquire differential valence in Experiment 2.

Main Methods:

• Forward and backward differential fear conditioning were employed.
• Trial-by-trial measures of conditioned stimulus (CS) valence and startle modulation were used.
• Startle probes were presented at early and late positions during the CS in Experiment 2.

Main Results:

• The dissociation between startle modulation and explicit valence evaluations in backward conditioning was replicated.
• Conditioned stimuli (CS+) were evaluated as less pleasant than CS-, yet startles elicited during CS+ were inhibited relative to CS-.
• Preliminary evidence suggests startle inhibition occurred early, but not late, during the CS+ in Experiment 2.

Conclusions:

• The findings replicate the dissociation between implicit (startle) and explicit (valence ratings) conditioned stimulus valence.
• This dissociation may arise because implicit and explicit measures are recorded at different times during CS presentation.
• The study provides preliminary evidence for temporal dynamics in the acquisition of differential valence during conditioning.