CHOICE study: time-dependent modulation of stress-induced effects on social decision making

Stress * both in real life and experimentally induced* can influence cognitive
and emotional functioning. Immediately after stress, subjects rapidly adjust
behavior to promote short-term instinctive behavior, whereas later on in the
aftermath of stress, behavior is aimed at restoring higher cortical functions
with more flexible and explorative behavior. Decision-making studies attempt to
understand our fundamental ability to process alternatives and to choose an
optimal course of action. Under conditions of acute stress, decision making
processes have been found to be impaired. Recently, the time-dependent
consequences of stress on decision making have been tested. Given that we live
in highly complex social environments, many of our important decisions are made
in the context of social interactions. Therefore, we aim to target the
time-specific effects of stress on social decision making performance and
possible gender effects. We hypothesize that directly following stress more
socially risky and egoistic decisions are made, whereas later on, more
advantageous long-term and altruistic decisions are chosen. Subjects will be
tested using the Trier Social Stress Test for Groups (TSST-G), which has
recently been proposed as a socially evaluative stress test that can test
multiple subjects simultaneously. If comparable or increased stress can be
induced while testing multiple subjects at the same time, this will lead to a
more efficient and robust protocol to induce standardized laboratory stress in
humans.

Study objectives
• Primary objective: Elucidate the effect of stress on modulation of social
decision making and its time dependency
• Secondary objectives:
o Reproduce the Trier Social Stress Test for Groups in both male and female
participants with a placebo control task in our experimental setup.
o Associate changes in autonomic and hormonal parameters after stress exposure
TSST subjects with (epi)genetic background.

Healthy adult participants will participate in this study. Half of the
participants are randomly assigned to the stress group; the other half are
assigned to the control group, both in a group protocol with 4 persons entering
the protocol at a time. Social decision making tests are administered either
directly after the stress/control condition (2 subjects) or 90 minutes
following the stress/control condition (2 subjects). The social-evaluative
group stress test consists of a public speaking task and an arithmetic test
which is an adaptation of the classic individual Trier Social Stress Test. The
control condition has a comparable cognitive load, while lacking the social
evaluative aspects of the stress condition. Throughout the study, heart rate en
skin temperature will be continuously measured. Furthermore, saliva samples
will be taken at different time points: before, during and after the stress
test to assess the hormonal, autonomic and immunological stress response.
Participants also complete various subjective stress questionnaires before,
during and after the stress/control condition. To prevent the possible confound
of a group stress test on social decision making directly after stress, an
additional experiment with individual stress and control conditions in male
healthy volunteers will be carried out.

Risks for volunteers are minimal. The stress test consists of a short public
speech test and/or a socially evaluated arithmetic test and does not lead to
extreme perceived stress levels. The time spent in the laboratory is limited to
3 hours and participants have sufficient time for breaks. No direct benefits
are present for volunteers. Concerning the risk analysis, a negligible risk
for participants is estimated. The stress test is often applied without any
known lasting disadvantageous effects.