An international team of scientists has recently made a groundbreaking discovery, when experts have discovered that people who were partially blind, due to injury to half of their brains, were able to “see” facial expressions and body language in pictures of other individuals. All of the images were shown on their blind side, where they had no remaining vision, the scientists report, quoted by Nature News. The test participants were also able to respond to the expressions or behavior, albeit unconsciously.
The investigators noticed that, when shown a picture of a smiling person, the test subjects involuntarily twitched a facial muscle usually associated with smiling. Conversely, when they “saw” an image of someone who looked fearful, they activated a muscle regularly used in frowning. The two people on whom the new research was conducted are from the United Kingdom, and they suffer from a condition known as partial cortical blindness, in which one side of their visual cortex is damaged.
This means that their eyes are intact, but that they can no longer process images in their brain. For instance, the researchers explain, if their left side of the brain is affected, then they cannot see with the right eye, and vice-versa. The experts believe the results of the study again show that we tend to synchronize our facial expressions to match those of people around us, a trait known as “emotional contagion.” In charge of the new study were Tilburg University in the Netherlands experts Marco Tamietto and Beatrice de Gelder. They argue that this happens even if we cannot see those around us.
“This is interesting evidence that we can recognize the emotions of others without needing to be visually aware of them,” University of Groningen neurophysiology of emotion expert and neuroscientist Christian Keysers, who has not been a direct part of the new investigation, adds. The involuntary muscle twitches were picked up using special electrodes, placed on the two patients' faces. These measurement devices are so sensitive, that they can detect muscle movements of which we, ourselves, are unaware.
“The subjects were not simply imitating the expression of others, because their faces responded whether the emotion was conveyed to them via facial expression or body language. They could sense emotion through an unconscious mechanism, and resonate with it,” Tamietto says.