It think these are two different things. Our brains can go on working on the problem even if we take a rest. If we rest with a the problem in our head, we are

It think these are two different things. Our brains can go on working on the problem even if we take a rest. If we rest with a the problem in our head, we are actually still focused. Probably, relaxing and letting the brain do its job without forcing it into one direction, often results in a good solution. Same with me, btw. The study, as I have understood it, is more about giving up with a problem. You give up faster, if you think your resources are limited. It is more the contrast between either you relax in order to solve a problem, or have some beers with your friends talking about soccer and thus escape.