TL;DR:
I suspect the apparent absence of spatial deficits in aphantasia may be an ascertainment artifact caused by studying unusually educated/high-WM people who have already successfully compensated for their condition. We should test aphantasia objectively using physiological tests like the pupilary response in an unselected population and examine whether the relationship between imagery, working memory and spatial performance changes.
In an early part of my life I worked as a post-grad Psychology researcher within a university. Recently I have been seeing a lot regarding "Aphantasia" and I had a weird sense of some concern regarding how it was being discussed and described.
So I have been digging into the cognitive science and neuroimaging data surrounding aphantasia and I believe I have identified what causes me concern and would like to share this with others and see what the response is.
While the condition is a measurable neurological reality, there is a critical selection bias in how researchers are currently studying it.
Basically, the current scientific consensus is likely missing a massive demographic, resulting in a skewed understanding of the baseline condition. Here is why I believe this to be the case:
1. We are testing the wrong way around (Flawed Screening)
Right now, the foundational physiological studies confirming aphantasia rely on a subjective survey called the Vividness of Visual Imagery Questionnaire (VVIQ) to find participants. Researchers take people who score a zero on the VVIQ, then run more objective physiological tests on them, such as measuring pupillary light response or binocular rivalry tests. Unsurprisingly, the people who self report having no visual imagery also fail the physiological tests.
However, to establish true population prevalence and eliminate semantic misunderstandings, this testing architecture must be inverted. Researchers need to conduct randomized, objective physiological screening (like pupil dilation) on the general population first, isolate those who lack the physiological response, and then see how they answer the VVIQ. Until we invert the pipeline, we are only studying people who possess the high degree of metacognition required to realize their internal rendering differs from the norm.
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2. The STEM and IQ/Intelligence Overrepresentation
While this is always a problem it is a particular issue here because of the mechanics of how aphantasia is tested. Because recruitment relies heavily on self reporting and university populations, current aphantasia cohorts are packed with individuals in Science, Technology, Engineering, and Mathematics (STEM). This means the literature is observing aphantasia exclusively through the lens of individuals with high baseline fluid intelligence and high working memory capacity. While this is a fairly generic problem, not specific to aphantasia, it massively compounds with the next issue.
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3. High IQ masks the deficit via algorithmic workarounds
In the studies conducted thus far, when aphantasic participants cannot rely on the computationally "cheap" heuristic of a mental picture, their brain has to work much harder to solve a spatial puzzle. It has to route the problem through propositional logic and spatial motor networks.
When researchers test aphantasics on spatial reasoning (like 3D mental rotation tasks), they find they are just as accurate as typical imagers, but they have significantly slower reaction times. A highly intelligent person has the raw working memory bandwidth to brute force this algorithmic heavy lifting. They get the right answer, it just takes them a fraction of a second longer. But this leaves less intelligent people simply unable to complete the task.
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4. The missing cohort: True aphantasia without the cognitive buffer
This is the serious gap in the current literature. If someone has average or lower fluid intelligence AND they cannot render visual heuristics, they lack the working memory capacity to execute that expensive logical workaround.
Instead of showing high accuracy and high latency on spatial tasks, their working memory will simply saturate, resulting in task failure. Because they fail, they are highly likely to be clinically categorized as having a general learning issues, poor memory, or a specific visuospatial deficit. AND, because they lack the metacognitive buffer to isolate their lack of mental imagery as the root cause, they are also less likely to self-identify as aphantasic. Currently the demographics cited above indicate over 20 percent of aphantasics work in these highly technical/STEM fields. Is this because they are genuinely over-represented or because we struggle to identify aphantasics outside of "intelligent" cohorts due to the above.
The Bottom Line
Current cognitive science claims that aphantasia does not inherently limit spatial reasoning. But that is only because researchers are almost certainly exclusively studying highly compensated individuals who possess the raw computational power to bypass the visual deficit. And this focus is NOT driven purely by traditional WEIRD selection bias. Until we establish objective general population screening, we are not studying baseline aphantasia; we are only studying high IQ compensation mechanics.
You both require high intelligence and capable meta-cognition to both identify and be identified as having aphantasia. This likely leads to over-diagnosis of intelligent participants who can readily exploit non-visual cognition for task completion, and massive under-diagnosis who have no alternative cognitive approaches and lack sufficient meta-cognition to articulate their issues.
Thank you for coming to my TED talk.