Scare tactics: scientists offer insights on what makes a perfect prank

Researchers come up with theory for why jump scares' are often followed by laughter - with advice on how to find sweet spot' of fear

Whether it's a friend jumping out from behind a bush or accidentally walking into a web of fake cobwebs, most of us will have fallen victim to a scare prank at some point.

Now scientists have come up with a theory for why jump scares" are so often followed by laughter - with insights for pranksters hoping to concoct Halloween tricks that tickle rather than terrify.