Seeing is believing, my mother used to say when she saw I hadn’t finished the spinach on my plate despite my protestations to the contrary. But what if the belief were to persist in the absence of visual corroboration? Suppose I simply closed my eyes and pointed at the plate? My mother, no solipsist, would merely laugh and tell me it would still be there if I ever chose to open my eyes again. I could never win at that –her open eyes trumped my temporarily closed ones every time. I tried that ruse so many times, I got so I could actually see the spinach and the plate even with my eyes firmly clamped shut.
Perhaps I was a slow child, but it did make me wonder about what seeing actually meant. Was it something that could continue even when I tried to turn it off? In the bedroom at night when the blinds were drawn and the room was black, I could still navigate fairly well -and if I did bump into something, I could usually sense it just before the collision.
People talked about noticing things out of the corners of their eyes –meaning when they weren’t looking at them, I guess- and when I grew older, I learned about the sensitivities and image resolution of different cells in the retina. The cone cells in the macula –which you use when you are actually looking at something- were good for colour discrimination and fine resolution, whereas the rod cells, peripheral to that, were more sensitive to light, but not at resolution.
That weird sensation of thinking someone is looking at you, I assumed, was something detected in that peripheral part of the retina by the rod cells –noticed, but not readily identified, and maybe, therefore, not consciously processed until you turned to focus your cones cells on it. It made sense, but every so often I am thrilled to find others who continue to be intrigued by the process: http://www.bbc.com/future/story/20170512-what-causes-that-feeling-of-being-watched
I had assumed that it was fairly straightforward –light hits the retinal cells in the eyes, the signal travels to the visual cortex in the brain, and then it makes us conscious of what the signal means. But, of course, it’s not quite as simple as that. ‘Once information leaves our eyes it travels to at least 10 distinct brain areas, each with their own specialised functions. […] The visual cortex supports our conscious vision, processing colour and fine detail to help produce the rich impression of the world we enjoy. But other parts of our brain are also processing different pieces of information, and these can be working away even when we don’t – or can’t – consciously perceive something.’
So what would happen if your visual cortex were destroyed by a stroke or trauma of some sort? You’d lose your conscious vision –your cortical vision… but ‘cortically blind is only mostly blind – the non-cortical visual areas can still operate. Although you can’t have the subjective impression of seeing anything without a visual cortex, you can respond to things captured by your eyes that are processed by these other brain areas’ –Blindsight, as a researcher name Larry Weiskrantz called it.
The BBC article reported on a study of a man with just such a condition. They were able to do a functional MRI to watch his brain while faces were presented to his ‘blind’ eyes. ‘The scanning results showed that our brains can be sensitive to what our conscious awareness isn’t. An area called the amygdala, thought to be responsible for processing emotions and information about faces, was more active when TD [the patient] was looking at the faces with direct, rather than averted, gaze. When TD was being watched, his amygdala responded, even though he didn’t know it.’
Exciting stuff. ‘[…]research like this shows that certain functions are simpler and maybe more fundamental to survival, and exist separately from our conscious visual awareness. Specifically, this study showed that we can detect that people are looking at us within our field of view – perhaps in the corner of our eye – even if we haven’t consciously noticed. It shows the brain basis for that subtle feeling that tells us we are being watched.’
The article reminded me of something that happened long ago in my gynaecology practice. At the time it seemed a rather trivial incident, but I suppose the fact that I can even remember it suggests that I found it intriguing nevertheless.
Prisha –I think that was her name- was a young woman whose baby I had delivered, a few years before. She returned every two or three years for her pap smear but I remember being surprised to see her again only a few months after her last visit. A tall, beautiful woman with what seemed to me to be an exquisite taste in saris, it was hard not to notice her in the waiting room whenever she visited. Long black hair that never managed to hide the large gold earrings, and the red bindi in the middle of her forehead marked her as an immediate attraction for whatever children happened to be playing on the carpet with their toys.
That day, however, their attention seemed to be focused on an older lady sitting beside her like a queen. Regal in bearing and bolt upright in posture, she was wearing a dark blue sari with gold trim, and as I recall her snow white hair was tucked away under a lighter blue scarf. I suppose what drew my attention to it was that she sat beside her daughter with her eyes closed even when she talked. A tow-headed little boy with large, blue, curious eyes was standing a few feet away staring at her. He would have been too young to have been Prisha’s son, so I assumed he was just fascinated, as I always was with the saris that Prisha wore. But it was more the older lady that had captured his eyes. As soon as I walked across the room to greet them, the little boy ran back to his mother who was sitting beside the window, but he continued to watch from the corner.
I was welcomed by a big smile as I approached Prisha. “I’m so happy to see you again, doctor,” she said, “but this time it’s my mother, Lakshmi, who needs your help.”
Her mother pursed her lips, but didn’t extend her hand to shake mine as I had expected. Her mouth drooped slightly on one side, but a smile broke through nonetheless.
“She is blind,” Prisha explained, “So I have come to help her, if that is alright with you. She only speaks Hindi, though, so I will also need to translate…”
As Prisha took her mother’s arm and helped her down the corridor to my office, I noticed a distinct limp and obvious weakness on one side.
“Mother had a stroke and lost her vision,” Prisha explained, when we were in the office. She’d settled her mother in a chair beside my desk and pulled another beside it for herself. The two talked for a moment while her mother fussed in her seat. “She says she is very nervous about consulting a man, doctor, but I have just reassured her that I trust you.” She smiled at her mother. “She can see nothing at all now, and with the continuing bit of paralysis, I think she feels particularly vulnerable.”
They chatted to each other in Hindi for a moment, when suddenly her mother’s face changed and I could see her tightening her grip on Prisha’s arm.
“Is there something bothering your mother?” I asked, wondering if perhaps she’d changed her mind about being examined by a man.
Prisha immediately smiled, but I could sense her tension. “She says someone is staring at her…”
I blushed and looked down at the surface of my desk. “I’m sorry, I didn’t mean…”
Prisha shook her head. “No, it’s not you, she says.”
“But…” I was confused. “Didn’t you say she couldn’t see anything?”
Prisha smiled, embarrassed. “Nothing at all. The neurologist says she’s completely blind… But she says she can sometimes feel things,” she continued and then shrugged.
Lakshmi seemed to be staring at the office door –if ‘staring’ is the right word, so I glanced over at it. The door wasn’t completely closed, and through what little space remained I could see a pair of large blue curious eyes examining us like a visitor in the zoo. And then, realizing they were noticed, they disappeared, and the pounding of little feet echoed down the corridor.
Lakshmi’s face relaxed and she said something to her daughter.
“It’s okay now, doctor,” she said, looking at her mother with a bemused expression. “She says the eyes are gone…”
There are more things in heaven and earth, Horatio… Blindsight? I don’t know, but whatever it was, I think I was privy to something special that day so long ago.