Learning to drive seemed to relax the rats. The researchers assessed this by measuring levels of two hormones: corticosterone, a marker of stress, and dehydroepiandrosterone, which counteracts stress. The ratio of dehydroepiandrosterone to corticosterone in the rats’ faeces increased over the course of their driving training.

This finding echoes Lambert’s previous work showing that rats become less stressed after they master difficult tasks like digging up buried food. They may get the same kind of satisfaction as we get when we perfect a new skill, she says. “In humans, we call this self-efficacy or agency.”

In support of this idea, the team found that rats that drove themselves had higher dehydroepiandrosterone levels and were less stressed than rats that were driven around as passengers in remote-controlled cars.

Read more: https://www.newscientist.com/article/2220721-scientists-have-trained-rats-to-drive-tiny-cars-to-collect-food/#ixzz63BIg6hEj