Stress makes us stooopid

If I had a slice of cheesecake for every time I've heard a business owner say "they're all just a bunch of idiots; it's quicker to do it myself", I'd be a wobbly diabetic. So why do supposedly competent people turn into "idiots" under pressure? The culprit is cortisol - cortisol is the stress chemical which is released in our brains to manage alertness, but it can all go horribly wrong if we live with heightened levels of cortisol for too long, and find ourselves in an inappropriate state of anxiety.
Anxiety is inversely correlated with creativity, the ability to learn and the capacity to see opportunities, it has a direct influence on cognitive capacity, and not in a good way. So the next time someone makes a mistake, rolling your eyes and snorting will just result in raised cortisol levels, increased anxiety and absolutely no chance of them ever getting it right - I'm sure you're smart enough to find another way of communicating instructive remediation?