Experimental Design and Timeline.

CSa: conditioned stimulus a; CSb: conditioned stimulus b; NS: neutral stimulus;USa: unconditioned stimulus a (sound); USb: unconditioned stimulus b (sound).On day 1 participants were first habituated to stimuli, immediately afterwards Acquisiton started. On day 2, participants reactivated memory of CSa and NS by one single presentation. After ten minutes, participants underwent extinction training. On day 3, participants were exposed to the aversive sounds. After ten minutes participants underwent Re-Extinction.