How you walk reveals to others how you are feeling, researchers say | Science

A long face isn’t the only sign that someone is depressed. The way people walk is also telling, particularly the swinging of their arms and legs, researchers say.

Scientists asked volunteers to guess people’s emotions from video clips of them walking and found that larger movements conveyed more aggression, while smaller movements implied fear and sadness.

Adjusting the videos to make the swings longer or shorter made emotions easier to infer, the study found, suggesting that coordinated swinging of the arms and legs was a key feature that people noticed.

The work expands the list of signals that humans rely on to quickly assess people’s emotions and highlights the specific movements that most convey the range of feelings people experience, scientists say.

“Walking is one of the most well-known and practiced whole-body movements in humans,” said Mina Wakabayashi, a researcher at the International Research Institute for Advanced Telecommunications in Kyoto, Japan, and lead author of the study. “For this reason, changes in emotional state can appear naturally in the way we walk.

“In our results, movements with larger swings of the arms and legs were more likely to be perceived as anger, while movements with smaller swings were more likely to be perceived as sad or fearful.”

For the study, scientists asked actors to recall life events that caused anger, happiness, fear, or sadness, then walk a short distance, dwelling on each memory. Participants wore tight clothing and reflective markers, allowing researchers to create side- and full-face point videos that captured their gait without their facial expressions or other bodily cues.

The volunteers then watched the videos and reported what emotion each approach evoked. According to the study, they recognized all the emotions described better than chance. “To some extent, the emotions intended by the walkers were actually perceived by the observers,” the researchers write in the Royal Society Open Science.

A second experiment looked at the particular movements that betrayed the emotions of the walkers. To do this, the researchers took gait videos of people expressing neutral emotions and manipulated the clips to exaggerate or tone down the swinging of the arms and legs. Again, observers saw more pronounced swings as aggressive, and less as sad or fearful.

Emotions are likely to influence all kinds of other ways people move their bodies, and the Kyoto team hopes to explore them in future work.

“Being able to infer emotions from body movements can help us quickly understand others during social interactions, even without words,” Wakabayashi said. That might mean spotting people’s emotions from afar and changing how we approach them, depending on whether they seem angry or sad, she added.

There are also potential applications of the work. If scientists can reliably predict people’s emotions from their movements, it could help identify vulnerable or threatening people in CCTV footage, or lead to wearable devices that monitor people’s mental states.

Researchers in Texas showed last month that a machine learning algorithm could predict anger, sadness, joy and fear from a person’s gait, but with limited accuracy. One potential advantage, they say, is that it may be more difficult to fake gait than to speak or express facial expressions.

Dr. Gu Eon Kang, a bioengineer at the University of Texas at Dallas and co-author of a study on machine learning, said another potential application was an “AI-based virtual aid” that could interpret a person’s emotions from their gait and respond accordingly.