‘We scan the brain to see how it creates a visual scene’
Describing aphantasia can be challenging even for Professor Fiona Macpherson, director of the Centre for the Study of Perceptual Experience at the University of Glasgow, who has studied the condition for eight years and worked on The Eye’s Mind project with Dr Adam Zeman.
“The description that you often get is that it’s someone who lacks visual imagery but even that’s not exactly accurate,” she said.
“Some people lack voluntary imagery, so they may have the odd image flash into their mind, but they can’t create an image.
“Some people have visual dreams. Some might have reduced auditory imagery, so are unable to hear a tune silently in their head or an inner voice.
“People with aphantasia can often give you a visual description of something; they just can’t conjure up an image of it in their mind.
“At the other end of the scale, you have hyperaphantasia where people’s visual imagery is every bit as vivid as actual sight.”
Estimating how many people it affects is also challenging. “People say 1-2% of the population but that is a really rough estimate,” said Macpherson.
“When we launched The Eye’s Mind in 2015, we were contacted by over 14,000 people who had aphantasia.
“We don’t know what causes it. We’re still at the beginning of understanding what processes in the brain produce imagery.”
Researchers at the University of Glasgow’s Centre for Cognitive Neuroimaging are using functional magnetic resonance imaging (FMRI) scans to detect differences in brain activity when processing internal visual imagery.
“We are looking into the brain activity related to imagery,” said Dr Lars Muckli, the centre’s director of FMRI.
“FMRI allows us to measure activity from many locations in the visual cortex when subjects who are blindfolded listen to sounds and attempt to create visual scenes and how that changes when people are imagining a visual scene.
“People’s imagery falls along a broad spectrum so we’re keen to investigate perceptual differences among people, whether they have aphantasia or not,” added Macpherson, who is now working on a perception census.
She wants people to share their experiences at the website perceptioncensus.dreamachine. world