Scientists say a phenomenon called "skin conductance," which changes when you sweat, is a surprisingly accurate method for detecting emotions — with future robots that detect this able to tell your emotions.

Because skin conductance changes when you sweat, they found a correlation between these measurements and videos that elicited feelings of fear, surprise and "family bonding emotions," making skin conductance an accurate method for detecting changes in emotion in real time.

For the study, scientists at Tokyo Metropolitan University attached probes to the fingers of 33 participants and showed them a variety of emotionally charged clips, including horror movie scenes, comedy sketches and family reunion videos. As they watched, the team measured how quickly participants' skin conductance peaked and how long it took to return to normal.

The study revealed distinct patterns for different emotions. Fear responses lasted the longest, which the scientists explained was likely an evolutionary trait that keeps humans alert to danger. Family bonding emotions, described as a mix of happiness and sadness, caused slower responses, which they said could have been because the two feelings interfered with each other.