People with aphantasia still have a blueprint for mental imagery, even if they can’t consciously ‘see’ it.
Research has revealed that the part of the brain that processes picture-like visual information is wired differently in people with aphantasia – a condition where individuals cannot voluntarily generate visual mental imagery.
An international team of scientists, including researchers from UNSW Sydney, used a type of MRI brain scanning to find out more about the neural processes in people with aphantasia.
They found that when people with aphantasia try to conjure an image in their mind’s eye, the primary visual cortex – the part of the brain that processes picture-like visual information – is activated, but any images that are produced remain unconscious to the individual.
Published today in Current Biology, the study, carried out by scientists at UNSW and South China Normal University, used a range of techniques to measure brain activity. Their findings challenge the existing theory that activity in the primary visual cortex directly produces conscious visual imagery.
“People with aphantasia actually do seem to have images of a sort, they remain too weak or distorted to become conscious or be measured by our standard measurement techniques,” says Prof. Joel Pearson, a co-author of the study based at UNSW’s School of Psychology. “This may be because the visual cortex is wired differently, as evidenced by the data in this new study. This research not only deepens our understanding of the brain but also pushes the boundaries of how we think about imagination and consciousness.”
What do we know about aphantasia?
Aphantasia has been verified in previous studies using sensory measures – for example through the changes in skin conductance in response to emotive stories, and a lack of pupil response to bright imagery.
“If you try and imagine a beach, you can probably ‘see’ it in your mind’s eye,” says Prof. Pearson. “People with aphantasia don’t get that mental picture – it’s just blank.”
A 2020 study, by Prof. Pearson’s Future Minds Lab at UNSW found that people with aphantasia reported a reduced ability to remember the past, imagine the future, and even dream.
While there is physiological evidence for aphantasia, little is understood about the underlying neural mechanisms of the condition.
Existing research, in psychology and neuroscience has demonstrated that visual experiences are closely linked to neural activity in the brain's early visual areas – the part that processes visual input at the earliest stages. The primary visual cortex is particularly important as it processes visual information in a picture-like format during perception and mental imagery, with its activation strength and size both tied to the vividness and strength of imagined content.
Previous studies have even decoded and reconstructed visual imagery based on neural activity in these areas, highlighting their role in creating subjective visual experiences. However, until now, it has been unclear whether people with aphantasia have this type of neural activity in their primary visual cortex.
Using MRI to test brain activity
The study involved two cohorts – 14 participants with aphantasia and 18 participants in a control group with typical imagery.
Participants underwent two different tests to assess their visual imagery, followed by functional MRI (fMRI) scans. The scans utilised Blood Oxygen Level Dependent (BOLD) fMRI, a technique that measures brain activity by detecting changes in blood oxygenation.
During the scans, participants viewed or imagined coloured striped patterns – which selectively activate the primary visual cortex. BOLD signals were recorded during either passive perception or attempts at imagining these patterns.
Challenging traditional results
Analysis of the results showed that participants with aphantasia showed a reduced BOLD response during perception compared to the control group.
While individuals with aphantasia reported little to no conscious imagery, distinct neural patterns were still generated during their imagery attempts, and the team were even able to use algorithms to ‘decode’ what people with aphantasia were attempting to imagine from the brain activity in the primary visual cortex. This suggests that there is indeed an image-specific representation in the brain, it just remains unconscious. These neural patterns are fundamentally different from perception and from those of people with mental imagery.
"Our results show that when someone with aphantasia tries to imagine, their brains still seem to create a representation in the early visual cortex. It’s like their brain is doing the math but skipping the final step of showing the result on a screen,” says Prof. Pearson. “This tells us that mental imagery isn’t just about the brain ‘lighting up’ – it’s about how that activity is formatted into something we can actually experience.”
Bridging the gap between the seen and unseen
Aphantasia is a relatively new area of research, and there is still plenty we don’t know.
“This research bridges the gap between the seen and the unseen. It’s incredible to think that people with aphantasia still have a neural blueprint for imagery, even if they can’t consciously ‘see’ it,” says Prof. Pearson.
These findings have broader implications for understanding how the brain generates conscious experiences and could inform clinical strategies for conditions involving altered mental imagery.
“We want and need to know more about how mental imagery is central to many psychological therapies and how super strong imagery is associated with disorders such as schizophrenia and Parkinson's disease,” says Prof. Pearson. “Understanding the neurological basis of aphantasia could have a major impact on a range of disorders and treatments to potentially give those with aphantasia mental imagery.”
While this study has broken into new territory in our understanding of aphantasia, further research is still required, including studies with greater sample sizes.
“Next, we plan to figure out why exactly these representations in the visual brain don't produce conscious imagery in those with aphantasia,” says Prof. Pearson.
Contact details:
For enquiries about this story please contact Lilly Matson.
Tel: 0426 656 007
Email: l.matson@unsw.edu.au
