The role of stress in social decision-making

Although a substantial literature is developing regarding the
effects of stress on decision-making (cf. Mather & Lighthall,
2012), the literature on stress and social decision-making is still
in the beginning stage. The present research extends this new
literature by examining the mediating and moderating factors of the
effect of stress on social decision-making. Furthermore, a novel
aspect of the research is its effort to connect the
information-processing and functional perspectives, with regard to
the acute stress response. Dual-mode theories state that emotional
processing, relative to cognitive processing, occurs early during
information processing (Murphy & Zajonc, 1993) and is
associated with stimulus-driven behaviors (Mischel & Metcalfe,
1999). Therefore, an intensification of emotional processing and
inhibition of cognitive control processes may lead to an earlier
and more stimulus-driven initiation of behavioral responses than
under normal circumstances. Moreover, such quick, automatic
behavioral responses to environmental stimuli may be particularly
useful during an acute stress response in that such responses could
help prevent disturbances to homeostasis (Nesse, 2005). In order to
facilitate such quick, automatic behavioral responses, emotional
processing may be intensified and cognitive processing inhibited,
during an acute stress response. In support of this notion,
empirical findings show that acute stress increases emotion-related
phenomena, such as reward salience (cf. Mather & Lighthall,
2012) and emotional learning (Luethi, Meier, & Sandi, 2008).
However, in a social decision-making context, such enhancement of
emotional processing may negatively affect the social interactions,
such that negative emotions from perceived unfairness may be
amplified when people are undergoing an acute stress response. More
specifically, in the context of an Ultimatum Game, people who are
stressed may reject more unfair offers than people under normal
conditions. This research tested this main hypothesis, and examined
emotions and trait emotion regulation tendencies as mediating and
moderating factors, respectively, of the relationship between acute
stress and Ultimatum Game rejections. These arguments are
elaborated in Chapters 1, 2, and 3 of this dissertation. In two
experiments, participants played the Ultimatum Game as the
Responder after completing a stress or control task. The Cold
Pressor Test was used as the stress induction method. Before and
after the Ultimatum Game, participants completed state emotion
ratings as well as trait emotion regulation questionnaires. Results
from Experiment 1 showed a successful stress induction, indicated
by higher cortisol levels in the stress, relative to control,
group. Moreover, Experiment 1 revealed a significant Stress x
Amount interaction, with stress having an effect on rejections of
unfair offers, in comparison to fair offers. However, the emotion
and emotion regulation results did not indicate the expected
pattern, with emotions being uncorrelated with fair, nor unfair
offers, and emotion regulation being associated with reduced
rejections of fair, but not unfair, offers. In Experiment 2, an
experimental manipulation designed to influence negative emotions,
namely partner type, was employed. Results did not replicate the
results of the first experiment, but unexpected results were found
involving partner type and negative emotions, namely that
participants who played with human partners, relative to those who
played with computer partners, rejected more unfair offers and that
negative emotions were positively correlated with rejections of
fair and unfair offers. The experiments and their results are
described in Chapter 4. It is difficult to draw firm conclusions
from these results, but they do offer a starting point for
interesting future research questions. Chapter 5 discusses some
implications as well as limitations of the present research.