Decision fatigue

Decision fatigue is a phrase popularised by John Tierney, and is the tendency for peoples' decision making to become impaired as a result of having recently taken multiple decisions.

Decision fatigue has been hypothesised to be a symptom, or a result of ego depletion. It differs from mental fatigue which describes the psychobiological state that results from a prolonged duration of demanding cognitive tasks, such as multi-tasking or switching between various tasks.

Some psychologists and economists use the term to describe impairments in decision making resulting specifically from a long duration of having to make decisions. Others view factors such as complexity of the decisions being made, repeated acts of self regulation, physiological fatigue, and sleep deprivation as implicated in the emergence of decision fatigue.

Decision fatigue is thought to be a result of unconscious, psychobiological processes, and is a reaction to sustained cognitive, emotional and decisional load, as opposed to a trait or deficiency. Decision fatigue is an emergent construct that has several possible applications in the fields of healthcare psychology, behavioural economics and healthcare policy.

Behavioural attributes of decision fatigue tend to reflect an underlying state of ego depletion and may symbolise an unconscious method whereby individuals adapt their behaviour to prevent further depletion. Individuals experiencing decision fatigue are more prone to avoidant behaviours, such as procrastination; Sjastad and Baumeister demonstrated that decision fatigued individuals are less willing to engage in planning, and were more avoidant, compared to controls. Decision fatigue may also induce passive behaviours, such as inaction and decision avoidance. Furthermore, individuals experiencing decision fatigue may display less persistence when putting effort into decision making, and thus may be prone to choosing the 'default' option. They may also be prone to impulsive, erratic or short-sighted behaviour.

Decision fatigue may also alter cognitive functioning. Some studies suggest that decision fatigue impairs cognitive abilities, especially executive functioning and reasoning abilities. For example Kathleen Vohs and Roy Baumeister found that the more that people had made frequent and deliberate choices, the less able they were to persist on a math task, regardless of how tired they were or how long they spent on the task.

There is evidence to suggest that decision fatigue may impact physiological endurance and self control. This was demonstrated in a series of studies which showed that participants who had made a long series of choices were less able to tolerate a bad-tasting drink, and were less able to tolerate pain, compared to controls. This indicates that decision fatigue impairs physiological as well as cognitive self-control.

Trade-offs, where either of two choices have positive and negative elements, are an advanced and energy-consuming form of decision making. A person who is mentally depleted becomes reluctant to make trade-offs, or makes very poor choices. Jonathan Levav at Stanford University designed experiments showing how decision fatigue can leave a person vulnerable to sales and marketing strategies designed to time the sale. "Decision fatigue helps explain why ordinarily sensible people...can't resist the dealer's offer to rustproof their new car."

Dean Spears of Princeton University has argued that decision fatigue caused by the constant need to make financial trade-offs is a major factor in trapping people in poverty. Given that financial situations force the poor to make so many trade-offs, they are left with less mental energy for other activities. "If a trip to the supermarket induces more decision fatigue in the poor than in the rich – because each purchase requires more mental trade-offs – by the time they reach the cash register, they'll have less willpower left to resist the Mars bars and Skittles. Not for nothing are these items called impulse purchases."

Decision fatigue can lead people to avoid decisions entirely, a phenomenon called "decision avoidance". In the formal approach to decision quality management, specific techniques have been devised to help managers cope with decision fatigue. Other forms of decision avoidance used to bypass trade-offs and the emotional costs of decision making can include selecting either the default, or status quo options, where these are available.

The "process of choosing may itself drain some of the self's precious resources, thereby leaving the executive function less capable of carrying out its other activities. Decision fatigue can therefore impair self-regulation". …

Several psychologists have challenged the effects of ego depletion, such as decision fatigue, on multiple grounds. One replication effort including 23 laboratories did not find an ego depletion effect to be significantly different from zero. This indicates that existing evidence may not be sufficient to support the existence of an ego depletion effect. Furthermore, even when an ego depletion effect does replicate, there is substantive heterogeneity in the effect size in the literature and the average effect size is small. As there is little evidence for ego depletion, then the existence of decision fatigue comes into question.

Stanford University Professor of Psychology Carol Dweck found "that while decision fatigue does occur, it primarily affects those who believe that willpower runs out quickly." She states that "people get fatigued or depleted after a taxing task only when they believe that willpower is a limited resource, but not when they believe it's not so limited". She notes that "in some cases, the people who believe that willpower is not so limited actually perform better after a taxing task."