Humans often make decisions in stressful situations, for example when the stakes are high and the potential consequences severe, or when the clock is ticking and the task demand is overwhelming. In response, a whole train of biological responses to stress has evolved to allow organisms to make a fight-or-flight response. When under stress, fast and effortless heuristics may dominate over slow and demanding deliberation in making decisions under uncertainty. Here, I review evidence from behavioral studies and neuroimaging research on decision making under stress and propose that stress elicits a switch from an analytic reasoning system to intuitive processes, and predict that this switch is associated with diminished activity in the prefrontal executive control regions and exaggerated activity in subcortical reactive emotion brain areas. Previous studies have shown that when stressed, individuals tend to make more habitual responses than goal-directed choices, be less likely to adjust their initial judgment, and rely more on gut feelings in social situations. It is possible that stress influences the arbitration between the emotion responses in subcortical regions and deliberative processes in the prefrontal cortex, so that final decisions are based on unexamined innate responses. Future research may further test this ‘stress induced deliberation-to-intuition’ (SIDI) model and examine its underlying neural mechanisms.

Sometimes when people are under stress, they hate to think, and it’s the time when they most need to think.

Stressful situations are not uncommon in everyday life, experienced for example by a doctor in the emergency room, a police officer in action, or a financial trader on a London trading floor. Individuals sometimes need to make important decisions when the stakes are high and when not enough information or cognitive resources are available to guarantee a sound choice. However, the high pressure may dramatically change decision making strategies, leading to different choices than would be made without such pressure. For example, individuals may approach situations differently depending on whether decisions are easy to make without far reaching consequences or life-altering and ambiguous. Although it is vital to understand decision making under stress, the majority of previous studies on decision making are carried out in non-stressful contexts. Only recent years have witnessed a remarkable burgeoning of decision-making research related to stress. But many findings in this field are mixed, leaving the specific effects of stress on judgment and decision making relatively unclear. The purpose of the current review is to summarize evidence from both human and animal studies on decisions under stress and to elucidate the neurobiological mechanisms underlying strategy shifting in the context of stress induced decision making.

Theories on decision making have proposed that there are two routes to making decisions: a fast route labeled System 1 and a slow route labeled System 2 (Kahneman, 2011, Evans, 2008, Gilovich et al., 2002, Evans and Stanovich, 2013). System 1 operates quickly and automatically with little effort. It activates our innate and instinctive responses to stimuli. For example, whenever a snake is detected or believed to be out there, instinctive fear is aroused and avoidance behavior is initiated without much thought. Such genetically hard-wired responses can enhance our ability to cope with vital environmental challenges of the type experienced during most of human history. Prolonged practice and experience also produce involuntary actions or habits. On the other hand, System 2 runs slowly and in an effortful manner, requiring complex computation. The pros and cons associated with each option are calculated and compared until an optimal choice can be made. Comparing both systems, System 2 is thought to be an evolutionarily more recent system and can flexibly check, modify, and override the decisions from System

Reward-based decision making refers to the process of examining reward magnitudes, probabilities, and risks, comparing options, and choosing a course of action. In the next section, I summarize the findings concerning stress and different decision making components, including the encoding of decision parameters (e.g. reward/punishment processing and risk analysis), executive control, and social decision making (see Table 1).