Measure of the startle eye-blink response was accomplished using EMG electrodes (Ag-AgCl) filled with saline gel, attached in the participant’s right orbicularis oculi region (Fridlund & Cacioppo, 1986). This signal was acquired and amplified with BIOPAC Systems’ (Goleta, CA) EMG100A module connected to BIOPAC Systems’ MP100WSW bioamplifier with a time constant of 1000-ms. Data was recorded and displayed using BIOPAC Systems’ AcqKnowledge III data acquisition software installed on a Pentium III computer. Following sensor attachment, participants rested quietly for 5 minutes to allow for initial adaptation to the hook-up procedure and assessment of signal quality. Startle response was scored offline manually in peak microvolts (μV) using the AcqKnowledge software.
