Why do you laugh when you’re tickled? Scientists at Humboldt University of Berlin are studying rats to try and solve the longstanding mystery. Given the right conditions, and enough back and belly tickling by a researcher, ratscan come to associate a researcher’s cotton gloved hand with the sensation of being tickled. Tickling makes them “giggle,” albeit in frequencies too high for human ears to hear. The rats develop a fondness for the human hands, chasing their scurrying fingers in circles.
The scientists observe the rat ticklishness, and track how their brain processes the sensation, hoping to uncover clues about the laugh-inducing feeling.