NIJMEGEN, Netherlands — Ever try to tickle yourself? Go ahead, stroke your own armpit or foot sole right now. Feel absolutely nothing? That’s because your brain is playing a fascinating trick on you — ...

For many of us, the tickling response is paradoxical — the playfulness it inspires is typically enjoyable, but the overstimulated nerves and loss of control can feel distressing. Whether you find it ...

Tell a silly joke, sneeze at a rather inopportune moment, remember something that embarrassed a good friend, forget which suit is trump in the card game you’re playing—there are a-thousand-and-one ...