The researchers haven’t yet published their results, but Kilteni can reveal some of what they have found. “The touch has to be strong and very fast to be perceived as ticklish,” says Kilteni, when it comes to what constitutes tickling. The preliminary analysis also shows that electroencephalography (EEG) recordings pick up different patterns of brain activity when someone experiences ticklish sensations. The researchers plan to investigate further, using functional MRI to home in on which areas of the brain process tickling sensations, though the robot must be adapted so it doesn’t interfere with the scanner. The lab’s scientists have also begun to explore the slippery question of whether people actually like to be tickled.