Why do people laugh when they are tickled? Laughter during tickling does not always mean pleasure and can act as a protective reaction to an unpleasant effect, says psychologist Marina Murabiova. According to the expert, a person may perceive the tickling as an invasion of personal boundaries, especially if he is unable to stop what is happening. However, the nature of such a response has not yet been fully explored. In the Netherlands, a special laboratory was opened to investigate the phenomenon, where volunteers tickle a robot named Hector. It has already been proven that the reaction to tickling is not related to jealousy nor to problems with the nervous system.