It ranks among the most curious phenomena in cognitive neuroscience. A handful of people in the world have “blindsight”: they are blind, but their non-conscious brain can still sense their surroundings.
Milina Cunning, from Wishaw in Scotland, lost her sight in her 20s, and later realised she had this blindsight ability. She has been studied extensively by researchers.
“If I was to throw a ping pong ball at Milina’s head, she would probably raise her arm and duck out of the way, even before she had any awareness of it,” says Jody Culham, a scientist who has scanned Cunning’s brain.
So what is it like to navigate the world in Milina’s shoes? Here, she describes the sensation in her own words:
“I went into hospital as sighted person. I was put into an induced coma because of all the health problems I had. And I was in the coma for 52 days. When I woke up, I saw completely black. I couldn’t see a thing. They said while I was in the coma I had a stroke which left me blind.”
“Over the months, thing started to change. Within six months, I thought I was seeing some colour but nobody really believed me. So I was put in contact with a neurologist, professor Gordon Dutton. And as soon as I saw him, he knew straight away, he confirmed that I had blindsight.
“When I went to see Dutton, there were quite a few tests he wanted to do. One of them was: he placed chairs out in the corridor in the hospital. He asked me to walk through the chairs. He said: ‘Just walk through at your normal walking pace.’ I walked my normal pace, and I kept bumping into them. So I got to the other end of the corridor, and he said: ‘Right, now try and walk a bit faster now and go back through them.’
“So I walked faster, and I just went through them, one by one, and I didn’t hit them once. And it was just amazing.
“The way Dutton explained it was ‘Don’t think about it too much, just go and do it. Don’t think too much in your mind.’ It was my subconscious mind telling me how to do that task and to avoid hitting the chairs.
“I can walk around the house ok, and tidy things up. But I can’t see them. I know they’re there. My brain is telling me. It’s the same if the family have left things lying in the middle of the living room floor. I say ‘you need to tidy up, so I don’t trip over these things’. If there is something lying there, like a handbag or shoes, I can see it and I miss it, or I go to pick it up.
“But I’ll try to look at you, and I know you’re sitting there, sitting close… but I just can’t see you.
“It’s strange the things I can see but I’m not meant to see because I’m blind.”