Aphantasia: Why I cannot see my children in my mind

Most people can picture images in their heads - the look of an apple, the appearance of their kitchen or the smile of their best friend - but not everyone can.

Those who cannot visualise anything in their mind's eye are probably among 1% of people with extreme aphantasia, according to a review of studies on the phenomenon.

They are also less likely to recognise faces, remember the sound of a piece of music or the feel of sandpaper, and more likely to work in science, maths or computing.

And up to 6% of people may experience some degree of aphantasia.

It is not a disorder and does not imply a lack of imagination but can have subtle effects on everyday life, says Prof Adam Zeman, honorary professor of neurology at the University of Exeter, who came up with the term nearly 10 years ago.

Mary Wathen, 43, from Cheltenham, Gloucs, finds it "totally mind-blowing" other people can create images in their head.

"I just cannot understand what they really mean - where is this image and what does it look like?" she says.

"To me, unless you can see something with your eyes, it's not there."

Mary cannot picture major events in her life such as her wedding day. And unless they are with her, she cannot even picture her two young boys.

"I don't bring up an image - I have all the memories, I just recall it very differently," Mary says.

"As someone once described it, all the hardware is working - but the monitor is not switched on."

Mary discovered she was unlike most other people only when chatting with friends, and was astonished to find her husband could easily visualise past events as if watching a film.

On the plus side, she says, she is a very good verbal communicator, because she assumes nothing - it is all about the words. She also feels things deeply.

"I'm a very emotional person who is led by gut instincts - so when recalling something, it's a feeling rather than an image," Mary says.

Mind maps have never been a useful tool for exams, for example, and fantasy fiction is a no-no because she simply cannot escape to that world in her mind.

"I only see what is real and in front of me - doesn't matter whether I saw it a minute or an hour ago," Mary says.

Prof Zeman discovered this way of experiencing the world when he saw a patient who had lost the ability to visualise.

When he wrote up the patient's case, others contacted him to say they had always been that way.

And Prof Zeman has since discovered there is an opposite extreme, hyperphantasia, in which people see images so vividly in their heads they cannot tell if they are real or imagined. An estimated 3% of us see the world this way.

"One term gave birth to the other," he says, after borrowing Aristotle's word for the mind's eye - "phantasia".

Prof Zeman says 17,000 people have contacted him in the past decade, with experiences of aphantasia and hyperphantasia.

Many said they knew they processed information differently to others but had unable to describe how.

Differences in connectivity between regions of the brain may explain why, Prof Zeman says.

Asked to picture an apple, for example, most people go through a succession of steps, including nudging the brain to remember what an apple looks like and activating the brain create an image of it.

But in those with aphantasia, that process can break down at any point.

"Thoughts remain thoughts," Prof Zeman says, "whereas for others, thought translates into sensory terms."

While aphantasics think about memories, other people are able to recollect and live those memories.

But intriguingly, many aphantasics can visualise images while dreaming - probably because it is a more spontaneous task beginning deep down in the brain, Prof Zeman says.

And aphantasia can have benefits. It can have a protective effect on someone's mental health, because they are more likely to live in the moment and less likely to imagine frightening or stressful events, for example.

But for Prof Zeman, "the big surprise" was aphantasic artists, who told him their struggle to visualise imagery gave them an extra incentive to make art, by using the canvas as their mind's eye.

Normally, it's hyperphantasics who are more likely to be creative, like Geraldine van Heemstra.

Geraldine, an artist, always had an "enormous imagination" as a child, building entire villages in her mind.

And she has always seen the alphabet in colour, as well as numbers and the days of the week.

At school, Geraldine used to change answers to maths problems because the colours of the numbers in her head looked wrong sitting next to each other.

But she discovered she saw the world differently to most others only when collaborating with musicians and dancers, painting swirls and shapes in response to their rhythms.

"I remember asking musicians how they saw music - but they didn't understand what I meant," Geraldine says.

"I thought all musicians saw notes in colour."

Geraldine has a similarly intense experience when painting.

"I can walk, sketch, take in the landscape and relive the experience later," she says.

Even when making plans to do something, Geraldine feels transported to the future.

"I can be going down another path and it will feel like deja vu," she says.

But constant visualising can also be tiring.

And Geraldine's brain can feel overloaded sometimes, making it hard to sleep.

Lots of question remain about aphantasia and hyperphantasia, such as what are the different sub-types and why it might be a genetic thing.

Data from large biobanks may provide the answer.

It has also been suggested aphantasics are more likely to have autism.

Prof Zeman says research suggests "conscious sensory imagery is not a prerequisite for human cognition" - or creative imagination.

And everyone pictures images in their mind differently.

"Our experience is not the norm and other people may have different inner lives," he adds.