Motivation and rewards

A 2016 replication across 23 labs and 2,141 people found an ego-depletion effect of d = 0.04, too small to tell apart from zero.

Motivation is what directs behaviour toward a goal. OpenStax separates intrinsic motivation, doing something for the satisfaction it brings, from extrinsic motivation, doing it to get something from others, such as pay or grades. Most real motivation is a mix, and the mix can change in ways that seem backwards.

When rewards backfire

Someone who bakes for fun takes a job in a bakery and stops baking at home. Psychologists call this the overjustification effect: an expected external reward can reduce interest in something that was enjoyable for its own sake. A meta-analysis by Edward Deci, Richard Koestner and Richard Ryan (1999) supports the effect, with two important conditions. Tangible rewards such as money harm intrinsic motivation more than verbal praise, which may even raise it. And rewards that are expected do more harm than rewards that come as a surprise. Other researchers, such as Cameron and Pierce (1994), argued that the harm is smaller than often claimed, so the size of the effect has been debated.

Classrooms show the same pattern. OpenStax notes that students are more intrinsically motivated when they feel they belong and are respected, when grading is less dominant, when they have some control, and when tasks are challenging but doable. Albert Bandura added self-efficacy, the belief that you can complete a task. People with high self-efficacy take on harder tasks and keep going after setbacks.

Arousal and performance

Robert Yerkes and John Dodson (1908) gave their names to the idea that performance is best at a middle level of arousal. Too little and you are bored; too much and anxiety gets in the way. The best level depends on the task: simple tasks are done best at fairly high arousal, complex ones at lower arousal. A little exam nerves can help on a quick recall test and hurt on a hard problem.

A famous idea that did not replicate well

In 1998 Roy Baumeister and colleagues proposed ego depletion: self-control draws on a limited resource, so using it on one task leaves less for the next. Hundreds of studies followed. Then in 2016 Martin Hagger and colleagues ran a preregistered replication in 23 laboratories with 2,141 participants. The effect was d = 0.04, with a 95 percent confidence interval from minus 0.07 to 0.15, not different from zero. A later multilab study with a different task pair, 12 labs and 1,775 people, found a small effect of d = 0.10. The fair conclusion is that if ego depletion exists, it is much smaller than the early studies suggested. Maslow's hierarchy of needs (1943) is another widely taught idea that OpenStax notes has been criticised for being subjective and for failing to account for what happens in the real world.