A Passage A Day

ลำดับตอนที่ #122 : The blind mind

http://www.bbc.com/future/story/20160524-this-man-had-no-idea-his-mind-is-blind-until-last-week

• By Helen Thomson

25 May 2016

Close your eyes and visualise the face of the person you love the most. The colour of their eyes, the texture of their hair, the detail of their skin. Can you imagine it? Philip can’t.

Although Philip, a 42-year old photographer from Toronto, is happily married, he can’t conjure up his wife’s face because he has no images of any kind in his mind’s eye. When he thinks about a face, it comes to him as an idea, as an intellectual concept, rather than a mental picture.

This newly described condition is called aphantasia and has prompted scientists to reexamine an experience that we so often take for granted – our imagination. What’s more, studying it is offering new insights into how we all might boost our visual imagery to improve our memory, increase our empathy and even gain new treatments for conditions like addiction and anxiety.

Aphantasia was first discovered in 1880, but has recently attracted much more attention thanks to a 2015 study by Adam Zeman at the University of Exeter and colleagues, who investigated the claims of 21 people who were unable to summon images to their mind’s eye.

Some of Zeman’s case studies reported the occasional flash of involuntary imagery during wake and sleep, even though they claimed to not be able to produce images on demand. The majority also reported problems with remembering things that happened in their past, possibly compensating for their lack of imagery by having a tendency to be good at maths, logic and verbal tasks.

I never realised that people could see images in their mind... I thought they just meant figuratively

Philip is a prime example. When he is asleep, his dreams are made up of the same visual images that we all experience, but during waking hours he finds it impossible to conjure up a mental picture of anything. “When I close my eyes I see my eyelids. It’s just blank,” he says. “I never realised that people could see images in their mind when they were awake. When they said ‘imagine this’ or ‘count sheep’ I thought they just meant figuratively.”

If you are able to generate internal images, it’s very hard to imagine what life is like without them. To understand the blind mind’s eye, it may be helpful to think about an abstract concept such as ‘peace’. There are no obvious – literal – images that are drawn to mind (apart from a metaphorical image like a dove perhaps) yet you are able to understand and imagine what peace is.

When Philip tries to picture a face, he knows intellectually what structures it involves, but he can’t visualise it in any way. “It’s very hard to explain what happens when I think about things like that,” he says. “If I try to picture my father’s face, for example, I would know that he had blue eyes or the size of his nose, but I wouldn’t be able to describe it in any more detail than that – I can’t bring his face to mind. I see nothing.”

Picture this

To understand the differences in each of our mental images, we have to be able to measure them – but it’s inherently difficult to analyse the private goings on in someone’s mind. Joel Pearson at the University of New South Wales has found the answer: not only can he objectively measure our imagination, but he can manipulate it too.

Not only can he objectively measure imagination, but he can manipulate it too

He does so using “binocular rivalry”. This is a simple task in which a person is briefly presented with two different images – say, green stripes and red spots. One image is shown to the left eye, the other image to the right eye. The brain can’t merge the two pictures into one cohesive image, and instead one image gets suppressed outside of our awareness, while the other is perceived.

You can manipulate which image is perceived by priming the brain to one or other of the images. You do this by showing one of the images to the person just before the task. That image is then more likely to be perceived when both images are viewed at once.

The same phenomenon happens when you ask a participant to imagine one of the images. This image is then more likely to be perceived in subsequent tasks. And the more vivid your imagination, the more likely you’ll see that same image in the following experiment. Over hundreds of trials, Pearson can use this phenomenon to work out just how good your imagination really is.

That explains it

Philip only recently discovered that he experienced the world differently after hearing a podcast presenter describing aphantasia and the inability to see mental images. It came as a complete surprise, he says. “I was like ‘what do you mean? People do that?’” He thought it was a joke, so he checked with his four-year old daughter. “I asked her whether she could picture an apple in her mind, she said ‘yeah, it’s green’. I was shocked.”

Suddenly, so many things in his life made sense. He had always had a notoriously bad memory. “I’m awful at remembering people’s names and faces – but now I know that other people can just picture what everyone looks like then of course that’s why they find it easier to remember that kind of stuff.”

He also has trouble finding his car in a car park – probably because he can’t picture where he has left it. “I always have to take a picture of the car or write down a shop that it is near otherwise I spend an hour searching for it.”

In a recent study, Pearson’s team analysed the brain mechanisms at work while someone uses their mind’s eye to produce mental images. They discovered that the size of a person’s visual cortex – the part of the brain responsible for perceiving images – correlated with how strong their mental imagery was. In unpublished work presented at ‘The Eye’s Mind’ conference in Norwich, UK this month, Pearson also described how people have stronger imagery when brain cells in this area are less active.

That kind of knowledge allows his team to develop experiments in which they can manipulate the activity of these brain cells using non-invasive brain stimulation to change the strength of a person’s mental imagery.

It’s easy to imagine how the research could allow people to boost their mental imagery

In doing so, they hope that they might be able to decrease the intrusive mental images that are symptoms of conditions such as anxiety, addiction and post-traumatic stress disorder. “Maybe we could tone down some of that imagery,” says Pearson.

On the other hand, Pearson says it might also be possible to bump up someone’s visual imagery. “It’s easy to imagine that people might want to boost their mental imagery to improve other aspects of cognition in which it is involved,” he says. We know, for example, that we canimprove our memory by conjuring vivid images to mind. And that preventing people from producing mental pictures affects their moral judgement: they find it easier to make ‘colder’, more logical decisions that would cause harm to others when they are not imagining the consequences.

“In theory, you might be able to manipulate visual imagery to improve eye witness statements, ethical decisions, memory and learning, the list goes on,” says Pearson.

But if mental imagery is involved in so many aspects of everyday life, why don’t people like Philip have more trouble? “Although people with strong mental imagery tend to do better in memory tasks,” says Pearson, “people with aphantasia still perform pretty well. They say they use semantics, or algorithms, or geometry – abstract non-visual strategies.” If your brain allows you to generate images, he says, then you’ll use them to help you perform certain tasks, and if you don’t, you tend to develop other strategies that can work just as well.

Philip agrees, “I’m sure my brain has compensated in other areas,” he says. For instance, he is great at impersonating other people’s voices. “I can imitate anyone, I can do any kind of accent. I don’t understand why other people find that so hard. I can hear people’s voices in my head as if they’re really speaking. Perhaps that’s one sense making up for another.”

Here and now

A visit to an online forum for people who experience aphantasia quickly reveals that many people with the condition think the trait is beneficial. One user believed that his aphantasia allowed him to live more in the here and now. “Not being able to picture the future [means] you can’t really live in it. The same thing about [the] past,” he says. Others agreed. “Because you can’t relive a moment, you cherish each moment that little bit more,” says another.

Philip also finds himself focusing more on the present than the past or the future. “I don’t like making plans, I find it difficult to think about the future and forget what I need to do unless I write it down, so I tend to be more spontaneous – I’m very good at working things out on the spot.”

Some talk about the benefits of not having to relive trauma

Other forum members talk about the benefits of not having to relive trauma or seeing images of scary or sad moments in their life. “I have watched a girlfriend convulse from an intentional overdose,” said one person, “I am grateful I do not have a visual memory to continue to relive that trauma.”

And just as we may struggle to imagine what our internal world would be like without images, people with aphantasia can struggle to imagine what their world be like with them. One forum user describes how she writes stories in her head for each of her memories or descriptions of things in her life. “Words are a beautiful thing,” she says. “I almost feel sorry for the people replacing those words with images. Sure images are great and all, but I love my words. If I suddenly started picturing images and my need to describe things in my mind diminished, I’d miss it.”

For Philip, well, he is still taking it all in. “It’s so weird that I never thought of this before,” he says, "that I never realised other people could picture things in their imagination. Why did nobody ever mention that to me? It blows my mind.”

conjure (v.)

to make something appear by magic, or as if by magic:

prompt (v.)

to make something happen:

insights (n.)

(the ability to have) a clear, deep, and sometimes sudden understanding of a complicated problem orsituation:

empathy (n.)

the ability to share someone else's feelings orexperiences by imagining what it would be like to be in that person's situation

summon (v.)

to order someone to come to or be present at aparticular place, or to officially arrange a meeting ofpeople:

to increase your courage or strength, especially with aneffort:

on demand.

Compensate (v.)

to pay someone money in exchange for something that has been lost or damaged or for some problem:

to provide something good or useful in place of something or to make someone feel better about something that has failed or been lost or missed:

verbal  (Adj.)

spoken rather than written:

figurative (adj.)

(of words and phrases) used not with their basic meaning but with a more imaginativemeaning, in order to create a special effect:

(of a painting, drawing, etc.) representing something as it really looks, rather than in an abstract way

Inherent (adj.)

existing as a natural or basic part of something:

manipulate (v.)

 to control something or someone toyour advantage, often unfairly or dishonestly:

 to control something using the hands:

to treat a part of the body, using the hands to push backbones into the correct position and put pressure onmuscles:

binocular  (Adj.)

 using both eyes to see things; made for use with botheyes

rivalry (n)

a situation in which people, businesses, etc. competewith each other for the same thing:

cohesive (adj.)

 united and working together effectively:

suppress (v.)

to end something by force:

priming (adj.)

main or most important:

of the best quality:

notorious (adj.)

 famous for something bad:

intrusive  (adj.)

affecting someone in a way that annoys them and makes them feel uncomfortable:

cognition (n.)

the use of conscious mental processes:

semantics (n.)

the study of meanings in a language:

convulse (v.)

to (cause to) shake violently with sudden uncontrolledmovements: