An appetitive conditioned stimulus enhances fear acquisition and impairs fear extinction

Results of Experiment 2. The mean percentage of time spent in magazine on the final trials of Stage 1 appetitive conditioning to conditioned stimuli (CSs) A and B and in the 30-sec pre-CS periods (A). The mean percentage of freezing during Stage 3 fear extinction to the AX and BX compounds and in the 30-sec pre-CS periods by Groups Protect and Control (B). The mean percentage of freezing during Stage 4 test to CS X and in the 30-sec pre-CS periods by Groups Protect and Control (C). All error bars shows 2 standard errors of the mean.