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Updated: Aug 18, 2026

Trace Fear Conditioning in Mice
Published on: March 20, 2014
Extending continuous versus discontinuous conditioned stimuli before versus after unconditioned stimuli
M Albert1, S Ricker, R A Bevins
1Department of Psychology, Concordia College, Amherst, Massachusetts.
Abstract:
Conditioned suppression was used with rats to study the effects of extending conditioned stimuli (CSs) before versus after the delivery of unconditioned stimuli. These extensions are termed B and A extensions, respectively. Within-group designs were used to compare the effects of extending CSs when 2-min parts of those CSs were separated by temporal gaps of 6 min versus a separation of no gap. The results were as follows: (a) B extensions weakened conditioning more than did A extensions, with or without gaps; (b) under some conditions, this asymmetrical effect persisted with extended training; (c) gaps between 2-min parts of a B extension had no detectable effect; and (d) under some parameter values, gaps between 2-min parts of an A extension weakened conditioning significantly. These results are better predicted by the Sometimes Opponent-Process model (SOP; A. R. Wagner, 1981) than by the Rescorla-Wagner-Frey-Sears real-time model (J. J. B. Ayres, M. Albert, & J. C. Bombace, 1987).
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