People who have prosopagnosia are more likely to be socially insecure. Photo: Li Hao/GT

The nose doesn't know

Tao's job includes interviewing job applicants - a task she finds rather challenging due to her impairment. She said when the applicants are all young women with long hair, she has to rely on calling out names to identify between different people.

"If we're looking at each other face to face, they're basically indistinguishable to me," she said.

Tao said she has tried focusing on individual facial features to help her recognize people, for example the shape of a person's face or the size of one's nose, but it proved to be of little help. The ability to recognize faces, according to most researchers in the field, is a holistic process wherein the face-as-a-whole is identified, rather than individual facial features.

Consequently, Tao said that she has found it easier to categorize people according to their height, body shape, hair style, skin color and whether or not they wear glasses.

"Whenever new employees join the company, it's a miserable process for me to learn to identify each of them," she said. "And even when I'm very close to someone, it's difficult for me to picture their faces clearly in my mind. For example, I can't picture my ex-boyfriend's face at all!"

Cheng Lehua, a professor of psychology at Sun Yat-sen University in Guangzhou, Guangdong Province, said that prosopagnosia is not a unitary disorder, meaning that there is no simple dividing line between whether people have it or not. Rather, people can show different levels of impairment when it comes to their ability to recognize faces.

Cheng said the diagnostic assessments used to identify face blindness were based on subjective responses - such as having to match a target face out of a line-up of faces.

He said most people who think they might have prosopagnosia are simply poorer at recognizing faces, but would not necessarily fit into the diagnostic criteria for the disorder. On the other hand, said Cheng, those who do have prosopagnosia often don't realize that there is anything abnormal about the way they perceive faces.

Blindsided by the digital age

Tao said her ability to recognize faces has gotten worse over time, and blamed the proliferation of social media platforms in which users are bombarded with a constant stream of faces.

Tao said she couldn't tell if people used their own headshots or pictures of a celebrity, and because she couldn't recognize faces, she had to keep notes to link her friends' Internet nicknames with their real names.

"Especially now that people all Photoshop their pictures," said Tao.

"I [also] think it's more difficult to tell the differences between one person and another because of the popularity of plastic surgeries [which make people all look the same]."

Cheng rejected the idea that social media could contribute to more people having prosopagnosia. Rather, he suggested that the prevalence of the Internet and social media simply meant there was more awareness about the disorder, because it made it easier for people who did have prosopagnosia to form communities, making more visible a disorder that used to be invisible.

"Face blindness has gotten more attention because of the Internet, especially because of the emphasis [of social media] on people's appearances," said Cheng. "People see a significantly larger number of photos of other people these days compared to during earlier stages of the Internet age, when the majority of the information was text."

The tendency for people to be flooded with pictures on social media may have made people more conscious of their difficulty in recognizing faces, said Cheng.

Tao admitted that she had always been aware of her difficulty in recognizing faces, even if she did not think there was anything abnormal about it. She said she remembers her mother trying to train her to identify people using flash cards of celebrities, but the faces all looked more or less the same to her. "I've been like this since I was a little girl," she said.

Awkward encounters

Liu Qingtian, a 25-year-old employee at a Beijing-based fast-moving consumer goods company, suspects she may suffer from face blindness. She said that she has had a fair share of awkward encounters because she has failed to recognize someone she knows.

"There are people I add [on WeChat] for work who I've only met one or two times. Afterward, I have no idea who they are, even if they are standing right in front of me," said Liu.

Liu recalls once bumping into a colleague from her former company, but being unable to recognize him. They ended up having a conversation, with Liu having no idea who he was.

All she saw was a blank face and all she thought about was how she could figure out who he was, said Liu. Eventually, Liu extricated herself from the conversation and called a friend, who told her who he was. Liu said in such scenarios, people sometimes misinterpret her as being "impolite."

Cheng said that people who had an impaired ability to recognize faces often felt less secure in social interactions. According to Cheng's research, among people with prosopagnosia, the proportion of those falling into anxious-avoidant types under the attachment theory of interpersonal relationships was higher than among the general population.

"Most people with face blindness have no idea about their own condition," said Cheng.

"[But] if they have problems with social interactions like interpersonal communication, they might read up on psychology or seek professional consultation."

Cheng said this approach could sometimes lead to misdiagnosis, as many doctors would resort to a psychological explanation for their difficulty with interpersonal communication, rather than attributing it to face blindness.