How terrible can face blindness be?

Recently, a nearly absurd news story happened in Mexico: a woman named Leonora in Solano State looked through her husband's mobile phone and found an intimate photo of her husband and a strange woman. She was so angry that she chopped her husband. But after investigation by the police, it was found that the photo was actually an old photo of Leonora and her husband many years ago.

How can a person not recognize his own face?

According to our common sense, "recognizing oneself" in a mirror or photo is a very natural, simple and clear thing, but it is not. Through various psychological experiments and research on various cognitive disorders, psychologists have found that "recognizing oneself/others' faces" is a complex process involving at least three different dimensions: recognition at the cognitive level, recognition at the emotional level, and the unification of sensory information. If there is a mistake in the analysis at any level, the face in front of you may become unfamiliar in an instant.

Sorry, your facial information cannot be retrieved

To understand this problem, we need to analyze what the process of "recognizing faces" is. The first is recognition at the cognitive level: when we see a face, the visual system will first analyze its features, such as the shape of the face, how big the eyes are, where the nose and mouth are... But this is only the first step. Next, the cognitive system will "label" different faces. In other words, our brain has a classified visual feature database for the various facial features of others. This "database" is located in the fusiform gyrus of the brain.

Brain structure diagram, the pink area is the fusiform gyrus | wikipedia.org

The fusiform gyrus is part of the temporal lobe and occipital lobe of the brain. Neuroscientists have discovered through brain imaging that there is a fusiform face area on the fusiform gyrus. The reason for this name is that the neurons here are very active when the test subject sees a human face, and basically only respond to facial information.

The facial image of others transmitted by the visual system will be decomposed into many local visual features, which will be compared one by one in the "database", and then our brain will draw a comprehensive conclusion: who does this face belong to?

You may have heard of the term "face blindness". The direct cause of face blindness is that the "facial feature database" in the brain cannot work properly. For example, in the 2011 movie "The Phantom Detective", the heroine Anna, played by Milla Jovovich, accidentally witnessed a murder and was injured in the head while escaping from the murderer, and suffered from face blindness. From then on, everyone's face, including her own, became strange in her eyes and deformed at any time. She could only recognize different people by features such as the color of their clothes and the style of their ties.

The cause of the onset of prosopagnosia in a considerable number of patients is brain damage caused by accidents, and the injured area affects the fusiform gyrus. As a result, they become like Anna in the film: after seeing another person's face, although they can perform a preliminary visual analysis and know that it is a human face, they cannot tell who the face belongs to, and can only identify it through reminders from others or other visual symbols.

That person is not me, he just looks like me!

However, another group of people have the symptom of "not being able to recognize themselves" because they suffer from a special psychological disease called "Capgras syndrome". They can clearly recognize their own and other people's faces from mirrors, photos, or face-to-face social interactions, but stubbornly refuse to believe that the face belongs to its original owner and thinks it is a stand-in actor.

Why does this strange phenomenon occur? This is because when we see ourselves and other people whose identities we know, the cognitive system will perform a "double-layer verification". The first layer is the fusiform gyrus to identify visual features; and the second layer is the recognition of the emotional system, which is entrusted to the emotional area of ​​the brain. When we see our loved ones, we will feel excited, and when we see our family, we will feel comforted, and so on.

The birth of emotion will cause our body to produce physiological arousal, which is manifested as slight sweating, faster heartbeat, faster breathing, etc. These arousal signals can be measured through skin conductivity reaction. Once these signals appear, it is equivalent to a kind of stamp certification of our emotional area: "I have a reaction when I see this person, so it proves that I know him/her."

Therefore, cognitive psychologists and neuroscientists have concluded that patients with capstone syndrome, due to the blockage of specific brain circuits, do not feel the intimacy they should have when seeing close people when they see their relatives and friends, and thus do not experience physiological arousal. In other words, due to the loss of the V certification sent by the emotional area, the brain will feel very confused: "This is obviously my own face, but why don't I feel anything!" This mismatch between visual information and emotional information will also produce a sense of psychological discomfort. In order to solve this confusion and discomfort, the brain came up with a solution: "This must not be the real me, but a substitute who is exactly like me."

Interestingly, even ordinary people with normal cognitive abilities can change their perception of their own appearance under certain external cues and manipulations, which involves the unification of sensory information.

Manos Tsakiris's face visual cognition interference experiment | Manos Tsakiris

British neuroscientist Manos Tsakiris conducted an interesting experiment. The volunteers who participated in the experiment had their faces repeatedly brushed by a machine brush while watching a video of a stranger's face being brushed in the same way on a computer screen. When the test was over, the researchers asked the volunteers to choose the face that was most similar to themselves from a series of facial images. Unexpectedly, these volunteers all chose a face that was more consistent with the stranger's face on the computer screen. This is because in the test, the volunteers, under the induction of continuous visual reinforcement, developed an identification and inner connection with the strange face on the screen. In this case, the most common scenario in reality is that we have been using various photo editing software and beauty filters for a long time, which has formed a visual cognitive bias: the real me does look like the highly beautified self in the filter.

Therefore, the unfortunate Ms. Leonora may not be a "oolong" criminal who deserves to be laughed at. She may have cognitive disorders due to some unfortunate experiences in life, and she has early signs of "face blindness". Therefore, people's perception of their own self-image is not static, but is always affected by external cues and the update of the "image database" in consciousness, and changes at any time. As the saying goes, "you can't step into the same river twice", our self-perception is also like a changeable river, coming from the past and moving towards the unknown distance.

References

[1] Damasio, AR, Damasio, H., & Van Hoesen, GW (1982). Prosopagnosia: anatomic basis and behavioral mechanisms. Neurology, 32(4), 331-331.

Diard-Detoeuf, C., Desmidt, T., Mondon, K., & Graux, J. (2016). A case of Capgras syndrome with one's own reflected image in a mirror. Neurocase, 22(2), 168-169.

[2] Hirstein, W., & Ramachandran, VS (1997). Capgras syndrome: a novel probe for understanding the neural representation of the identity and familiarity of persons. Proceedings of the Royal Society of London. Series B: Biological Sciences, 264(1380), 437-444.

[3] Kanwisher, N., McDermott, J., & Chun, MM (1997). The fusiform face area: a module in human extrastriate cortex specialized for face perception. Journal of neuroscience, 17(11), 4302-4311.

[4] Tsakiris, M. (2008). Looking for myself: current multisensory input alters self-face recognition. PloS one, 3(12), e4040.

Author: Ji Xiaodier

Editor: Zhu Buchong