2.2 Laboratory procedure
Upon arrival at the room in which that laboratory protocol was administered, participants were seated and informed consent was affirmed. Participants then completed a self-report survey including psychopathic trait measures. While participants completed the survey a research associate randomized the participant into either the SSST or countdown task. After completion of the survey, sensors for ANS measurement were attached. Heart rate was measured with a NeuLog infrared LED transmitter and receiver. This device monitors heart rate between 0 – 240 beats per minute at 100 samples/second. Skin conductance was measured with a NeuLog galvanic skin response sensor with Velcro connectors, this device has the sensor amplitude at a range of 10 microSiemens at a sample rate of 100 samples/second. After the sensors were placed and checked, ANS recording was initiated as the participants watched a relaxing video (Coral Sea Dreaming, Small World Music Inc.) for 3 minutes in order to induce an accurate ANS baseline (Piferi et al. 2000; de Wied et al., 2012). After the conclusion of the baseline video the relevant experimental conditions were described to the participants.
Participants randomized into the SSST were informed that they had 2 minutes to prepare a 2-minute speech about their biggest faults and weaknesses. Participants were told their speech would be recorded and evaluated later. SSSTs have been shown to induce changes in ANS activity and hormones (testosterone and cortisol) associated with psychopathic traits and antisocial behaviors (Armstrong et al., 2019; Armstrong et al., 2022). At 1.5 minutes participants were informed they had 30 seconds in preparation time remaining. At the 2-minute mark the research associate appeared to turn on a video recording device and asked the participant to begin their speech before leaving the room. After a full two-minutes, the research associate reentered the room and notified the participant to stop delivering their speech.
The countdown task followed the structure for this task reported in earlier work on associations between ANS activity and psychopathic traits (Fung et al., 2005; MacDougall et al., 2019; Wang et al. 2012). Specifically, participants were instructed to observe a computer monitor while wearing headphones. They were then read the following prompt:
In this situation, you will see numbers counting down on the computer screen from 12-0. One number will appear every second. When you see the number 0, you will hear a loud noise for 1 second. Sometimes this loud noise will come on without any warning, however. There is nothing you need to do in the task apart from keeping your head as still as you can. Do you have any questions?
After any questions were answered a countdown task comprised of four 45-second trials began. All trials began with a 12-second rest period. In Trials 1 and 3 (signaled), the rest period was followed by a 12-second numeric countdown appearing on the computer screen. When the countdown reached 0, the participant experienced a 1-second 90 dB white noise blast. Reaction to the noise blast was captured in the 20-seconds followed. In Trials 2 and 4 (unsignaled), the 12-second resting period was followed by 12-second (unsignaled) anticipation period, a 1-second 90 dB noise blast and a 20-second reactivity period.