Let's admit it: being "face blind" sounds less like a real condition, and more like a hastily-slapped-together excuse for why you failed to say hi to Bill from IT for the third time this week. But to those who suffer from the phenomenon – which is more properly known as prosopagnosia – it can be a real and debilitating disorder.
Now, a new study suggests that the number of people with face blindness may be quite a bit higher than we previously thought.
“Face blindness… can be caused by a brain injury to occipital or temporal regions, referred to as acquired prosopagnosia, which affects one in 30,000 people in the United States,” Joseph DeGutis, Harvard Medical School associate professor of psychiatry at VA Boston and senior author of the study, told Harvard Medicine News.
But another type of prosopagnosia – the kind caused by genetic or developmental abnormalities, affecting people as a lifelong condition rather than as a result of trauma – is much more common, he explained.
“[That is] referred to as developmental prosopagnosia,” he said. “[It] affect[s] one in 33 people.”
That’s the conclusion of DeGutis and his team’s new study, which involved more than 3,000 participants taking part in a web-based questionnaire and two objective tests. First, they were asked about any difficulties they might experience recognizing faces in their everyday lives; then, in the tests, the researchers investigated how hard it was for subjects to learn new faces or recognize famous faces.
Overall, just over 100 of the participants turned out to have some form of face blindness: the results showed that 31 people out of the 3,341 total had “major” prosopagnosia, while another 72 had a milder form of the disorder.
That’s a hit rate of just over three percent, or one in 33 – more common than the one in 40 that the condition was previously assumed to affect. For DeGutis and his team, the reason for that is clear: the current diagnostic criteria are simply too strict, they believe.
“The majority of researchers have used overly strict diagnostic criteria and many individuals with significant face recognition problems in daily life have been wrongly told they do not have prosopagnosia,” DeGutis noted.
“Expanding the diagnosis is important because knowing that you have real objective evidence of prosopagnosia, even a mild form, can help you take steps to reduce its negative impacts on daily life, such as telling consequential coworkers, or seeking treatment.”
Such a move could have profound implications for those affected by the condition. Evidence suggests that milder forms of face blindness respond better to certain treatments, such as cognitive training, than more severe cases, DeGutis explained, and so expanding the diagnostic criteria could allow many more people to take control over their condition.
But more than that, the results may suggest we need to rethink face blindness – not as one single condition, but as a spectrum disorder.
“Prosopagnosia lies on a continuum,” DeGutis confirmed. “Stricter vs. looser diagnostic criteria employed in prosopagnosia studies in the past 13 years have identified mechanistically very similar populations, providing justification for expanding the criteria to include those with milder forms of it.”
With these new results and recommendations, the team hope to bring reassurance to millions who may have the disorder and not know it.
“Face blindness can be a socially debilitating disorder… [that] can cause social distress and embarrassment,” DeGutis said. “Recognizing someone is a social signal, indicating that ‘you are important to me.’”
“In a world where social isolation is on the rise, especially in teens and young adults, fostering and maintaining social bonds and good face-to-face interactions are more important than ever,” he concluded.
The results can be found in the journal Cortex.