Answer: Their eye movements.
The researchers trained the deep learning artificial intelligence (AI) platform by giving 42 students off-the-shelf headsets that tracked their eye movements to wear as they ran errands. They also asked the students to complete a personality type questionnaire. The AI was able to use the combined results to establish similarities between the two.
“We found that we were able to reliably predict four of the big five personality traits — neuroticism, extraversion, agreeableness, conscientiousness — as well as perceptual curiosity only from eye movements,” Andreas Bulling, a professor at Max Planck Institute for Informatics in Germany, told Digital Trends.
In the future, this technology might be able to give robots a certain level of empathy toward humans, which could improve human-robot interactions.