Converging evidence for one-trial context fear conditioning with an immediate shock: importance of shock potency.
In a sample of 208 Holtzman-descended albino rats, we found evidence with 4 measures of conditioning (freezing, defecation, side crossing, and nose crossing) that a single 2-s, 1.0-mA immediate shock could condition fear to a context (Experiments 1, 2, and 4). When we reduced the shock intensity to 0.5 mA, we obtained a complete immediate-shock conditioning deficit according to all measures in Experiment 3 and to all but the defecation measure in Experiment 4. Results suggest two conclusions: (a) Differences in shock potency between laboratories may help explain discrepant findings about whether immediate shock supports contextual conditioning; (b) theories of contextual conditioning need a mechanism that permits that conditioning to result from immediate shock.
Bevins
R A
RA
Department of Psychology, University of Nebraska-Lincoln 68588-0308, USA. rbevins@unlinfo.unl.edu or to joeayres@psych.umass.edu
McPhee
J E
JE
Rauhut
A S
AS
Ayres
J J
JJ
D000818:Animals; D001143:Arousal; D001245:Association Learning; D001288:Attention; D003214:Conditioning, Classical; D004597:Electroshock; D005239:Fear; D005260:Female; D008297:Male; D009043:Motor Activity; D051381:Rats; D012153:Retention, Psychology