When a friend’s face is turned away from us, we readily retrieve information about that person’s body to identify them — even when we don’t realize we’re doing it, according to new research published in Psychological Science.
“Psychologists and computer scientists have concentrated almost exclusively on the role of the face in person recognition,” explains lead researcher Allyson Rice of the University of Texas at Dallas. “But our results show that the body can also provide important and useful identity information for person recognition.”
During the study, college-age participants viewed pictures of two people side by side and were asked to identify whether the images showed the same person or two different people. Some of the image pairs looked very similar even though they were actually two different people, while other image pairs looked very different even though they were the same person.
The image pairs were chosen so that the subjects’ faces were more ambiguous and not very helpful in determining their identities. The researchers edited the pictures in several of the experiments, omitting the subjects’ bodies or faces to determine which features were most important for successful identification.
Overall, participants were able to guess correctly when the images showed the same person in a complete picture—faces and bodies. They were also just as accurate in identifying image pairs in which the faces were blocked out and only the bodies were shown.
Interestingly, participants were less accurate when they saw images that included the subjects’ faces but not their bodies. In fact, seeing the subjects’ bodies seemed to increase their accuracy in identifying the subjects.
After viewing the pictures, participants reported that they used the nose, face shape, ears, mouth, and eyes as tools for identifying even though their results suggested otherwise.
“This left us with a paradox,” the researchers write. “The recognition data clearly indicated the use of body information for identification. However, the subjective ratings suggested that participants were unaware of how important the body was in their decision.”
To figure out this paradox, the researchers used eye-tracking equipment to determine where participants were actually looking, and the results were clear: The participants spent more time looking at the body when the face did not provide enough information to make an accurate identification.
“Eye movements revealed a highly efficient and adaptive strategy for finding the most useful identity information in any given image of a person,” said Rice. “These systems are employed currently in law enforcement and security settings, but they sometimes fail when the quality of the facial image is poor.”
By showing that we don’t just rely on faces to identify others, the study opens up new avenues for developing and refining computer-based recognition systems.
“We will continue comparing humans to machines on these new challenges,” said Professor Alice O’Toole at The University of Texas at Dallas. “By looking at the way computer face recognition systems work, we often learn new and surprising things about the way humans recognize other people.”
Source: Psychological Science