'I didn't recognise my own son': Face Blindness affects one in 50

Radio personality Dr Karl Kruszelnicki has lifted the lid on a bizarre but serious condition which prevents thousands of Australians from being able to recognise faces, even their own.

What might sound like an excuse for poor memory is actually neurological defect causing facial features to become visually meaningless.

Dr Karl couldn’t even recognise the face of reporter Steve Pennells when he was sitting right in front of him and revealed the only way he can greet people when he is at work in the Triple J office is to have a seating plan on-hand.

Hairstyle, glasses or body shape are key indicators to people suffering from Face Blindness — or prosopagnosia — but relying on facial features is almost impossible.

Karl can't tell who Steve Pennells is by his face even when he is right in front of him

"Prosopagnosia can come either as a result of a trauma or you’re born with it. But we still don’t really understand what’s going on," Dr Karl said.

"The brain is more complicated than the beginning of the universe."

"[At work] I smile at everybody… I can recognise a few people’s names and I carry a little map of people’s names and where they sit at Triple J."

Sufferers liken it to someone without prosopagnosia trying to identify a face upside-down — it is extremely difficult, but when turned right side up recall kicks in.

"I was at a three day conference on comedy-writing and there was this guy I thought I knew, maybe. [On the] third day I said, “look do I know you?” I’m Karl” and he said “Hi Karl, I’m Damien. I’ve just finished working with you for six months on our second series [of TV show] Sleek Geeks,'" Dr Karl said.

Lucy painted faces for a whole year to try and help her condition

In our test Karl failed to identify even the world's most famous faces, including Kim Kardashian and Marylin Monroe.

But not recognising celebrities is the least of Carol Barnard's problems. She remembers being at Melbourne airport unable to identify her own son, who also has Face Blindness.

"Three times he walked past me and clearly he didn’t notice me either and in the end we both happened to look at each other and realise that we were mother and son," Carol said.

"So that was a significant moment, really, when I couldn’t recognise my own son."

Science shows a strong genetic link in sufferers but a cause is still unidentified.

Carol takes Dr Romina Palermo's test to help gather evidence about the condition

"I think it’s genetic… My cousin in Sydney has a problem with recognising elderly ladies with short grey hair."

Even looking in a mirror Carol sometimes sees a stranger.

"This has happened to me in restaurants where you know there’s been mirrors all around and I’ve thought, 'Who’s that old woman staring at me, why does she keep looking at me'?"

Fellow sufferer, Lucy Barnard began drawing faces in the hope that her art would highlight the facial features she couldn’t see.

"It’s really tricky, because obviously I can see that the features of a face clearly, there’s nothing wrong with my vision. The problem is when it comes to conjuring in my mind what somebody looks like I just can’t do it."

She discovered the cause of her difficulty at university where, as part of her neuroscience degree, she attended a lecture on Face Blindness.

"All I can think of when I try and picture someone is a blank space and then their hair, what kind of clothes they’re wearing or more often I think about the way they move, and the way they laugh, and little expressions that they make."

Lucy Barnard was dating Matt for five years and didn't recognise him when he got a haircut

Her then boyfriend, Matt Ryan – who is still a good mate — had his doubts about the disorder and believed Lucy was just forgetful until he got a new hairstyle.

"When I had a haircut and she didn’t recognise me… she didn’t recognise her partner of five years."

Romina Palermo is a psychologist from the University of Western Australia.

She keeps a register of people with face blindness and tests them to discover more about the condition.

"We do know that people with prosopagnosia see a face. They see all the parts of the face but what they aren’t extracting efficiently is the parts of the face that are cues to identity," Romina Palermo said.

Another challenge face blindness presents is watching television – because to them the characters all look the same.

"For me the hardest thing is where you’ve got a movie or TV series where you’ve got a whole lot of people in relationships with each other," Karl Krszelniki said.

Lucy eventually gave up trying to follow visual entertainment.

"I don’t even try. I don’t watch TV. I don’t look at magazines. There’s just no point because I’m just looking at a bunch of nothing."

Could you suffer from Face Blindness? Take the test to find out: Dr Rominia Palermo's face memory test