Worn out from thinking? You might forego the better deal

In 10 seconds? A recent study examined biological mechanisms of mental fatigue and how it influenced economic decision-making for selecting either a small reward right away or a high reward that people would get later after doing extra work.

What’s the story? Researchers have found that compared to people who engaged for six hours of easy thinking (cognitive) tasks, people doing hard cognitive tasks for the same period had higher glutamate levels. This was measured with magnetic resonance spectroscopy (MRS). Crucially, subjects invested less energy (mental effort) during deciding what reward to pick, and selected smaller rewards that needed no extra work. In other words: after a hard day’s work we tend do go for quick wins rather than going the extra “mental mile” for some bigger future win.