Picture a beach. The sun is rising, the blue waves are crashing, and the white-gold sand is sparkling. Calming, isn't it?
Now visualise your desk at work. The park near your house. Your parents' faces.
For some of you, the images in your mind will be crystal clear. For others there's merely a faint image that flickers in and out. But we can all basically visualise, right?
Not all of us, reports News.com.au.
For some people, the visual mind is a blank canvas. Being asked to think of the ocean or a recent vacation or the face of a loved one conjures up nothing. There is no "mind's eye". No pictorial imagination. Just darkness.
In recent years, scientists have dubbed the term 'aphantasia' — the absence of fantasy.
Ariel Rowan, a counsellor from Sydney, is what you'd call aphantastic. When asked to picture a beach, he said there's no degree to which he's able to visualise it.
"I can't see a thing," he told news.com.au. "It's completely blank. I still have an imagination — it's just not a visual one. I come at things in a different way."
It's mind-blowing to realise people's minds don't work the same as yours does. Ariel said he realised he had aphantasia when he came across an online article about an old facial recognition study.
He found himself relating to the subjects, who failed to visualise faces presented to them as part of an experiment. Ariel began asking friends if they could relate to this, and a switch flicked in his mind.
"The only subject I really struggled with in school was geography," he said. "I always had trouble trying to picture where things were on a map, because I couldn't visualise it."
But he stresses it's not a disability — nor does it necessarily make him less creative than the average person. "I'm an artist as well," he said. "And I actually have a really good sense of direction. You can sort of feel where things are and where they're going — I guess the same way a blind person would feel their way through."
While some aphantastics report every sense being affected — for instance, they'd be unable to read this sentence in Homer Simpson's voice, or recall the taste of chocolate — Ariel says it's just his visual mind that's affected.
The phenomenon actually dates back to 1880, when British sociologist Francis Galton conducted a statistical study on mental imagery.
But it didn't become a prominent talking point until Blake Ross, the co-creator of Mozilla Firefox, penned an essay on Facebook called "Aphantasia: How It Feels To Be Blind In Your Mind".
"If you tell me to imagine a beach, I ruminate on the 'concept' of a beach," he explained. "I know there's sand. I know there's water. I know there's a sun, maybe a lifeguard. I know facts about beaches. I know a beach when I see it, and I can do verbal gymnastics with the word itself.
"But I cannot flash to beaches I've visited. I have no visual, audio, emotional or otherwise sensory experience. I have no capacity to create any kind of mental image of a beach, whether I close my eyes or open them, whether I'm reading the word in a book or concentrating on the idea for hours at a time — or whether I'm standing on the beach itself."
Like Ariel, Blake said he reached out to a number of friends and family, most of whom confirmed he was in the minority with his thoughts.
Blake's case is more extreme than Ariel's. Ariel confirmed his dreams were unaffected by the condition, as were his other four senses; he could still "hear" voices that weren't his own. Blake says there is no visual or sensory component to the very few dreams he has had, nor has he ever had a song stuck in his head.
He also describes reading as a very different process. Where the average person reading a descriptive fantasy novel would likely visualise the images in their mind, Blake "finds the bones" of a descriptive sentence — he essentially reduces the physical descriptions, sounds and movements of characters down to one fact: There is a character.
Joel Pearson, an associate professor in the school of psychology at UNSW, has been studying aphantasia for several years. His team of researchers are preparing to launch a crowd-funding campaign which he hopes will help give aphantastics mental imagery.
He told news.com.au that the visualisation process can vary greatly from person to person, and estimates that around 4 or 5 per cent of people may have aphantasia.
Other reports suggest it's around one in 50 who are affected, but Dr Pearson thinks this lower number is due to the nature of the condition, and people being unaware that their mind works differently to the norm until they read articles like this one.
"We've known generally that there's a spectrum," he told news.com.au. "There's the far-end case where you have zero imagery — total blackness — and then the other end where people can visualise things very vividly."
In his experience, aphantastics who approach him tend to be quite shocked when they realise that some people can have a conscious visual experience. For some, it can be quite an emotional discovery, and he said a few use it to justify failures in their life, or a lack of creativity.
"People fall into the trap of thinking it's a disability or a disease," he said. "That's why we're doing this big project looking at the role of anxiety and neurological disorders in aphantasia. Aphantastics can perform the same tasks fairly normally — they just do it in different ways."
One of Dr Pearson's studies exploits a phenomenon called binocular rivalry. The experiment worked by asking someone to imagine the colour red, before showing a red image to one eye and a green image to the other eye simultaneously.
Pearson found that people who don't have aphantasia would perceive the red image most of the time, while those with aphantasia would perceive the red and green images in equal amounts. This, he said, suggests people with aphantasia were unable to mentally create the colour red as instructed in the first place.
There could also be a relationship between visualisation and moral judgment — or the ability to feel empathy. A separate experiment evokes the classical thought experiment of "The Fat Man", which is summed up as so: "As before, a trolley is hurtling down a track towards five people.
You are on a bridge under which it will pass, and you can stop it by putting something very heavy in front of it. As it happens, there is a very fat man next to you — your only way to stop the trolley is to push him over the bridge and on to the track, killing him to save five. Should you proceed?"
According to the study, people with stronger visualisation abilities were less likely to push "the fat man" on to the bridge, because they could more clearly visualise pushing him to his death.
So, can aphantastic people "learn" to visualise things? Not at this stage. But Dr Pearson is working on it.
"We know we can take someone who visualises things on the low end and help them get to medium imagery by doing stimulation tests," said Dr Pearson. "But what we don't know is if we can go from nothing to something. That's what we're looking at now."
If you're one of the few people now realising you belong to this minority of non-visualisers, sorry for blowing your mind.