Having a blind mind’s eye: What is aphantasia?
Try imagining a scene at the beach. For some people, the experience will be intensely visual and feel like they are looking at a photo, others might see it hazily or missing some of the colours.
For an even smaller group, they will think of the beach scene more in concepts. They know what a beach looks like but can’t actually see one in their mind’s eye.
This condition, called aphantasia, affects between one and five percent of the population though many don’t realise they have it until they share their experiences with someone without the condition or encounter it online.
While this leads to a lot of self-diagnosis, researchers are looking for more objective diagnostic tools.
Researchers at Macquarie University have experimented with identifying new methods of diagnosis.
In one experiment, the researchers attached electrodes to people’s skin to measure how much they sweat while imagining scary scenarios. The results showed that people with aphantasia didn’t sweat in the same way as people who could see images in their mind’s eye, but they did when shown actual scary images.
All in our heads
Though the condition has technically been known since the 1800s, a history of imagery research as a low-priority field meant the condition was only named in 2015 when neurologist Professor Adam Zeman and colleagues coined the term - ‘a’ meaning none, and ‘phantasia’ meaning imagery.
Though historical research surrounding survivors of strokes and traumatic brain injuries had found they had reported losing the ability to visualise images, the advent of neuroimaging fast-tracked research in the area.
Neuroimaging includes commonly known techniques such as MRIs and CT scans, and this family of techniques showed that specific visual regions of the brain are activated when we imagine things.
For example, if you were shown a picture of a tree, a pattern of activation would occur in these visual regions. When you go to imagine that tree later, your brain attempts to recreate that neural pattern - meaning that you reactivate the neurons in a similar way to how they were activated when you first saw the tree.
Why do we visualise things?
Though the reason isn’t fully clear, being able to visualise things can help us remember things from the past and imagine future scenarios to make decisions.
People with aphantasia aren’t that disadvantaged though, instead finding other ways to help them remember things and plan for the future.