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.