title: Fear acquisition requires awareness in trace but not delay conditioning.
abstract: The present study explored fear acquisition in differential delay versus trace conditioning in regard to the potential role of the acquired contingency awareness. One of two neutral pictures (CS+) either coterminated with (delay group; n=32) or was followed by the aversive unconditioned stimulus (UCS) after CS offset (trace group; n=32), while startle blink and skin conductance responses (SCR) were measured. As expected, the acquisition of conditioned startle potentiation in delay conditioning was independent of contingency awareness. In contrast, fear-potentiated startle in trace conditioning was only observed for those participants who were aware of the CS-UCS contingencies. SCR conditioning was generally only obtained for aware participants. The present results suggest a more implicit learning process in delay fear conditioning, whereas the explicit acquisition of contingency awareness might be a prerequisite for trace fear conditioning.
authors.affiliation: Department of Psychology, University of Greifswald, Greifswald, Germany. weike@uni-greifswald.de
authors.forename: Almut I
authors.initials: AI
authors.lastname: Weike
authors.forename: Harald T
authors.initials: HT
authors.lastname: Schupp
authors.forename: Alfons O
authors.initials: AO
authors.lastname: Hamm
mesh_terms: D000328:Adult; D001364:Awareness / Q000502:physiology*; D001767:Blinking / Q000502:physiology; D003213:Conditioning, Psychological / Q000502:physiology*; D003627:Data Interpretation, Statistical; D004576:Electromyography; D004597:Electroshock; D005149:Facial Expression; D005239:Fear / Q000502:physiology*; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology; D006801:Humans; D008297:Male; D010775:Photic Stimulation