【得了脸盲症都是自爹妈的错】

【得了脸盲症都是自爹妈的错】看了一眼帅哥美女你就能记住他们吗?也许很多人能做到,但有一些人可做不到。科学研究表明,约有2%的人天生拥有不同形式的脸盲症。大脑中有固定的区域负责形成脸部图像,这个区域受损则会导致人不能识别脸部。但是绝大多数人拥有正常的大脑功能。研究者发现,婴儿时期见到的人越少则越可能得脸盲症。而且出生一个月内是关键时期,在这个时期没有见到足够多的人,那么很可能导致脸盲症。

Three babies in a row pulling funny faces

Last month,  in category B for “anyone with a non-professional interest, including undergraduates”. More than 640 articles were submitted in total, with the top 20 judged by a panel consisting of neuroscientistSophie Scott, materials scientist Mark Miodownik, science writer Anjana Ahuja, the Observer’s Nicola Davis, the Guardian’s Ian Sample and the director of the Wellcome Trust, Jeremy Farrar. A former partner in a law firm, Kate has now changed tack to pursue a career in science communication. Here is her piece in full, with minor edits.

Prosopagnosia – a Common Problem, Commonly Overlooked
“I once asked Clara who she was. It was so embarrassing, but she’d had a haircut, so how was I to know?” That’s Rachel, she’s 14 and counts Clara as one of her oldest and best friends. There’s nothing wrong with Rachel’s sight, yet she struggles to recognise others. Why? Rachel is face blind.

Most of us take for granted the fact that we recognise someone after a quick glance at their face. We don’t realise we’re doing something very different when we look at a face compared with when we look at anything else. To get a feeling of how peculiar facial recognition is, try recognising people by looking at their hands, instead of their faces. Tricky? That’s exactly how Rachel feels – only she’s not looking at hands, she’s looking straight into someone’s eyes.

Specific areas of the brain process facial information. Damage to those areas gives rise to prosopagnosia or “face blindness”: an inability or difficulty with recognising faces. While brain damage-induced prosopagnosia is rare, prosopagnosia itself is not. Studies suggest around 2% of the population could have some form of prosopagnosia. These “developmental” prosopagnosics seem to be born without the ability to recognise faces and don’t acquire it, relying instead on all manner of cues, from gait to hairstyles, to tell people apart.

Kirsten Dalrymple from the University of Minnesota is one of a handful of researchers looking into developmental prosopagnosia. Her particular interest is in prosopagnosic children. “Some seem to cope without much of a problem but, for others, it’s a totally different story,” she says. “They can become very socially withdrawn and can also be at risk of walking off with strangers.”

Dalrymple points out that lack of awareness of the condition among childcare specialists and the public, is a serious issue. Many parents of prosopagnosic children go through a number of specialists before realising what is causing their child’s peculiar behaviour. And it is usually seeing something about “face blindness” online or in the media, rather than a specialist’s deduction, that makes the penny drop.

What causes developmental prosopagnosia is a puzzle. It’s thought that the normal brain develops its facial recognition skill through innate knowledge and a learning ability.

When tested at less than an hour old, babies will track simple drawings of faces for longer than they will track anything else. They are born with a fascination for faces, but studies suggest they need experience, too, to develop normal face recognition. There are suggestions that individuals raised in orphanages have difficulty recognising new faces. If only a few faces are seen in childhood, it’s possible that the brain does not get enough information to optimise its facial-recognition abilities.

Learning facial recognition might take place, or at least start, very soon after birth: People born with cataracts have abnormal facial recognition abilities in later life, even if the cataracts were removed at the age of two months. That ties in with indications that newborns’ innate interest in faces trails off after the age of one month.

Despite the importance of infant brain development, there may be processes that can be harnessed to help a face-blind child become a non face-blind adult. The brain needs to perceive a face and to remember it; it must identify a face as a face, then realise that it has seen that particular face before. Evidence suggests that facial perception and facial memory are dissociable processes; one can function without the other and the existence of one without the other can be probed. Dalrymple finds that children with developmental prosopagnosia seem to have problems with perception and memory processes. Some prosopagnosic adults, however, only have problems with face memory. If there are adults – but not children – with impaired face memory and unimpaired face perception, it may be that the face perception element can improve.

Treatment of prosopagnosia is a long way off, but raising awareness of the condition would be a huge help to those affected. Understanding that someone isn’t ignoring you deliberately lessens the likelihood of offence; understanding a child’s behaviour enables you to help them. When a child like Rachel fails to recognise a classmate – again – it might be time to recognise the face of prosopagnosia.

http://www.theguardian.com/science/2014/nov/23/faceblindness-prosopagnosia-kate-szell-wellcome-trust-science-writing-prize-face-blindness


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