“…Continuous CS-UCS parings (100%) usually results in rapid acquisition, but also in rapid extinction in human participants (LaBar, Gatenby, Gore, LeDoux, & Phelps, 1998). Therefore, a partial reinforcement schedule was chosen to decrease extinction learning (Phelps, Delgado, Nearing, & LeDoux, 2004) and, thereby, allow us to examine the impact of fear acquisition in a test phase where no more US were presented (see Alpers, Ruhleder, Walz, Mühlberger, & Pauli, 2005). Trials were separated by inter-trial-intervals (ITIs) ranging from 20 s to 35 s. During five ITIs in each block, a startle probe was delivered with inter-probe-intervals of at least 15 s. During fear conditioning, SCRs and startle eyeblink responses were measured as physiological indices of fear acquisition.…”