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CHAPTER 5 128 safety behavior availability to remind participants of the CS-US contingencies. From the Extinction phase onwards, A and C were no longer followed by the US. In the Return of safety behavior phase, safety behavior was again available during C trials, but not for A and B. Finally, in the Test phase, A, B, and C were presented once without availability of safety behavior. The experimental task is graphically depicted in Table 2. The order of trial types was randomized within each phase, with the restriction that there were no more than two consecutive trials of the same type. Furthermore, the final three trials of the Extinction phase were A, B, and C, and C was always presented last in the Test phase. Table 1. Design of the experimental task Pavlovian acquisition Safety behavior acquisition Extinction Return of safety behavior Test A+ (3) A+ (1) A- (7) A- (6) A- (1) A*(+) (2) B- (6) B- (1) B- (4) B- (3) B- (1) B*- (2) C+ (3) C+ (1) C- (7) C*- (6) C- (1) C*(+) (2) Note . A, B, and C refer to visual stimuli (CSs); + and – refer to presence and absence, respectively, of a loud noise (US) following the CSs; * indicates the availability of the safety behavior; (+) indicates that participants only heard the loud noise if they did not use safety behavior; numbers in parentheses indicate the number of trials of each type.