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Imageless imagery in aphantasia: decoding non-sensory imagery in aphantasia

DOI: 10.21203/rs.3.rs-3162223/v1
Meng, M., Chang, S., Zhang, X., & Pearson, J. (n.d.). Imageless imagery in aphantasia: decoding non-sensory imagery in aphantasia. doi:10.21203/rs.3.rs-3162223/v1

Abstract

Activity in early visual cortex is thought to tightly couple with conscious experience, including feedback-driven mental imagery. However, the state of mental imagery, what takes its place or how any activity relates to qualia in those with aphantasia (a complete lack of visual imagery) remains unknown. In the current study, univariate (amplitude) and multivariate (decoding) BOLD signals during imagery attempts were recorded in primary visual cortex. Unlike in those with imagery, neural signatures in those with validated aphantasia were ipsilateral and could not be cross-decoded with perceptual representations. Further, perception-induced neural activation was weaker in those with aphantasia compared to controls. Together, these data suggest that an imagery-related representation, but with less or transformed sensory information, exists in the primary visual cortex of those with aphantasia. Our data challenges the classic view that activity in primary visual cortex should result in sensory qualia.

Authors

  • Ming Meng4
  • Shuai Chang4
  • Xinyu Zhang3
  • Joel Pearson33

What This Study Is About

Researchers wanted to know what happens in the brain when people with aphantasia—the inability to create mental imagery (pictures in the mind)—try to imagine something. They aimed to find out if the brain still processes "imaginary" information even if the person doesn't "see" anything.

How They Studied It

The team worked with 32 volunteers: 14 with aphantasia and 18 "typical" visualizers. Participants lay in an fMRI scanner (a giant magnet that maps brain activity by tracking blood flow) while performing two tasks:
1. Perception: Looking at actual green and red patterns on a screen.
2. Imagery: Trying their best to imagine those same patterns.
The researchers then used "decoding" software—kind of like a digital mind-reader—to see if they could guess what a person was imagining just by looking at their brain activity.

What They Found

The results were a scientific plot twist! Even though the participants with aphantasia reported seeing nothing, the computer could still "decode" what they were trying to imagine based on their brain activity.
However, there was a huge difference:
  • Typical Visualizers: Their brain activity for *imagining* looked almost exactly like their brain activity for *seeing*. It’s like the brain re-plays a movie it already watched.
  • Aphantasics: Their brain activity for imagining did not match their activity for seeing. It was a completely different "code." Their brains were definitely doing something, but it wasn't "visual" in the traditional sense.

What This Might Mean

This suggests that aphantasia isn't just a "broken" imagination. Instead, the brain might be using a different strategy—like thinking in "blueprints" or "descriptions" rather than "photographs."
It suggests that for a mental image to become a conscious picture, the brain needs to use a specific sensory code that aphantasic brains seem to skip. Because this was a small study with 32 people, we can't say this is true for everyone, but it "suggests" aphantasia is about how the brain formats information.

One Interesting Detail

The researchers found that people with aphantasia actually had weaker brain responses even when looking at *real* objects. It’s as if their "visual volume" is turned down slightly lower than everyone else's, both for real sight and for imagination!
This summary was generated by AI and may contain errors. Always refer to the original paper for accuracy.