Facial Stimuli and Skin Conductance in Research

The CSs consisted of three pictures of Caucasian male faces with neutral facial expressions, from the NimStim Set of Facial Expressions (Models: 23, 28, 36; Tottenham et al., 2009 (link)). Electrical stimulation was delivered through a pair of Ag electrodes of 20 × 25 mm with a fixed interelectrode mid-distance of 45 mm. Shock deliverance was controlled by a monopolar DC-pulse electric stimulation (STM200; Biopac Systems Inc., www.biopac.com). Between the electrodes and the skin, a conductive gel (Signa, Parker) was applied. For SCR assessment two Ag/AgCl electrodes of 20 × 16 mm were attached with to the medial phalanges of the first and third fingers of the non-preferred hand. The physiological signals were amplified and recorded using BIOPAC Systems (Santa Barbara, CA) hardware at a rate of 250 samples per second. Data were analyzed using AcqKnowledge software (BIOPAC Systems). Participants sat in front of a standard 21-inch cathode ray tube (CRT1) monitor (100 cm distance) in a sound attenuated chamber. The resolution of the screen was 800 × 600 pixels with a refresh rate of 60 Hz. The experiment was presented in E-Prime 2.0 (Schneider et al., 2002 ).