What This Study Is About
This paper argues that aphantasia—the inability to create mental images—is not a single, uniform condition. Instead, it suggests there are many different "varieties" of aphantasia caused by different underlying processes in the brain.
How They Studied It
This is a theoretical "letter" or perspective piece rather than a new laboratory experiment. The author reviewed existing research on mental imagery and aphantasia to categorize the different ways people experience a lack of imagery. The paper compares how aphantasia is currently identified (mostly through self-report questionnaires) versus how it could be identified using brain scans and physical measurements like pupil dilation.
What They Found
The author identified several distinct types of aphantasia:
- Voluntary vs. Involuntary: Some people cannot picture things on purpose but still have vivid dreams or involuntary "flashbacks," while others have no mental imagery at all.
- Unimodal vs. Multimodal: Some lack only visual imagery, while others lack imagery in all senses, including sound, touch, and smell.
- Object vs. Spatial: Many people with aphantasia can still accurately describe where objects are in a room (spatial imagery) even if they cannot "see" the objects themselves (object imagery).
- Biological Differences: The paper suggests that "prefrontal" aphantasia might involve a struggle to control imagery, while "occipital" aphantasia might involve the brain's inability to generate the image itself.
What This Might Mean
Treating aphantasia as one single category might be slowing down scientific progress. If researchers group everyone together, they might miss important discoveries about how different brains work. The author suggests that future studies should use more than just questionnaires to identify participants, adding physical tests to better understand which specific "type" of aphantasia a person has.
One Interesting Detail
The author uses an analogy of blindness: just as someone might be unable to see due to a problem with their eyes, their optic nerve, or their brain, people may have aphantasia for many different biological reasons.