Neuroscience and Brain Mechanisms of Aphantasia

This file compares claims from /research/02_neuroscience.md against r/Aphantasia accounts retrieved via hybrid search (k=25 per claim).

A caveat up front: lay accounts cannot directly corroborate fMRI activation maps, lesion-network mapping, or 7T millimetre-scale connectivity analyses. What they can do is describe the phenomena the neuroscience predicts — flat autonomic responses to imagined threat, absent pupil constriction to imagined brightness, preserved spatial reasoning despite no object imagery, dreaming without waking imagery, and acquired-after-stroke onset. The match is striking.

Claim 1: "Aphantasics showed essentially flat SCL to the same stories"

Source: Wicken, Keogh & Pearson (2021), Proceedings of the Royal Society B, 288(1946), 20210267, "The critical role of mental imagery in human emotion: insights from fear-based imagery and aphantasia"

Supporting accounts

"After using multi-method verification of aphantasia, we show that this condition, but not the general population, is associated with a flat-line physiological response (skin conductance levels) to reading and imagining frightening stories. Importantly, we show in a second experiment that this difference in physiological responses to fear-inducing stimuli is not found when perceptually viewing fearful images." 2022 · t1_ichwzyi ↗

"Yeah reading anything scary gets no reaction out of me, love my horror films though" 2025 · t1_mwmku8f ↗

"When you are scared, you sweat. Not a lot, but it affects how well your skin conducts electricity so it can be measured. When people read a visually scary story, they sweat about the same as if they are shown similarly visually scary images. When aphants read visually scary stories they don't sweat as much as when they are shown visually scary images." 2025 · t1_mwbsmrj ↗

"The two groups read scary stories and the Aphants were less affected than others but when they showed scary photos there was little to no difference in the reactions of Aphants and others - they were equally scared." 2020 · t1_fcvtc7t ↗

Contradicting / qualifying accounts

"Lol not me I'm easily terrified by scary stories. I can't visualise the source of fear, but that doesn't mean it's not causing me fear." 2021 · t1_gqogrow ↗

"If I can see it with my eyes I am capable of fear. If I am thinking about something scary or reading about it, the fear is somewhat or greatly reduced. I dislike horror movies much more than horror novels." 2025 · t1_mz5v1ft ↗

The second "contradicting" account actually exhibits the predicted asymmetry (perceptual fear preserved, imagined fear blunted) while reporting against the caricature.

Extending observations

"Likely, this is very common. Personally, I don't feel emotional about memories at all. I can recall the facts of how I felt, like I know I felt sad when my friend passed or cried with joy when my kids were born, but I can't re-feel those same emotions when I talk about these things with others" 2021 · t1_gul8m25 ↗

This extends the Wicken et al. finding from imagined threat to autobiographical emotional memory — exactly the bridge Monzel et al. (2024) make at the hippocampus-visual-cortex level.

Claim 2: "In aphantasics: no significant luminance effect on pupil size during imagery, while perceptual pupil responses to actual brightness were preserved"

Source: Kay, Keogh, Andrillon & Pearson (2022), eLife, 11, e72484, "The pupillary light response as a physiological index of aphantasia, sensory and phenomenological imagery strength"

Supporting accounts

"Exposing participants to bright and dark shapes, the researchers found that aphantasic individuals exhibited the same pupillary response as the general population: constriction to bright, dilation to dark." 2022 · t3_u7t93w ↗

"Yes, when a visualizer imagines a bright light their pupils will shrink, or if they imagine darkness their eyes will dilate somewhat." 2022 · t1_i5gdj4s ↗

"One of the tests for aphantasia is checking whether the pupils dilate and constrict in reaction to imagined light. People without aphantasia see the light changing in their mind's eye and it's real enough for the pupils to react, while the pupils of people with aphantasia don't react as there's only the concept of a light rather than an image of one." 2026 · t1_o8khvfc ↗

"when people tell me to visualize something, I always assumed they were being metaphorical. I cannot envision things, I don't have a third eye, and to be honest it astounds me that there's such a thing. so if you told me to imagine a light, I could close my eyes and focus, and there's no light coming. so I guess it makes sense why my pupils wouldn't constrict" 2025 · t1_nw53emu ↗

Contradicting / qualifying accounts

None surfaced in top-25; the corpus uniformly accepts the finding when raised.

Extending observations

"I remember hearing how if you imagine a bright light your pupils would dilate, and I tried to see if that was a thing while looking in the mirror, tried to imagine a bright light and it didn't work." 2022 · t1_i670l0c ↗

A first-person home replication attempt — null result, consistent with the study.

Claim 3: "Resting-state: stronger functional connectivity between prefrontal cortex (BAs 9, 10, 11) and the visual-occipital network in hyperphantasics versus aphantasics"

Source: Milton, Fulford, Dance, Macpherson, Onians, Winlove & Zeman (2021), Cerebral Cortex Communications, 2(2), tgab035; convergent with Liu, Hadj-Bouziane, Jolly, Volle & Bartolomeo (2025), Cortex, on FIN-frontoparietal disconnection

Supporting accounts

"Aphantasia is linked to reduced activity in the brain’s visual network, especially between the visual cortex and prefrontal cortex. Dreaming is controlled by a different system, the default mode network (DMN), which could explain why some still dream visually." 2025 · t1_mf3e8nj ↗

"As far as I know, there’s evidence that aphantasics have an abnormality in the connection between the prefrontal cortex and visual cortex. People with ADHD have a difference in the prefrontal cortex. That might be a reason to expect a correlation" 2023 · t1_j89bgy4 ↗

"Found aphantasics activate similar visual areas during imagery, but with reduced functional connectivity between the Fusiform Imagery Node and frontoparietal areas" 2025 · t1_ntk2pnq ↗

"In summary, visual cortex excitability reliably correlated negatively with the strength of visual imagery using both fMRI and TMS as measurement tools. Modulating visual cortex excitability also altered the strength of visual imagery. Specifically decreasing visual cortex excitability led to increased visual imagery strength. There was also evidence that altering prefrontal cortex excitability modulates visual imagery strength, but in the opposite pattern to visual cortex – increasing prefrontal cortex excitability led to increased imagery strength." 2021 · t1_gvzaal2 ↗

Contradicting / qualifying accounts

None surfaced in top-25. Several accounts speculate about exact mechanism but all accept the basic frontoparietal-visual disconnection frame.

Extending observations

"Visualization is thinking in images, for that you need a connection between the thinking and the seeing (prefrontal and visual cortex if I’m not mistaken). We lack that connection and the only explanation I’ve ever found anywhere for that is that our visual cortex is kinda busy all the time so the thoughts from the prefrontal cortex never reaches the back of our brains where the visual cortex is." 2020 · t1_fompujk ↗

This lay description tracks Keogh, Bergmann & Pearson (2020) almost sentence-for-sentence: a noisy/over-busy V1 swamps the weak top-down signal.

Claim 4: "Spatial imagery (Object-Spatial Imagery Questionnaire spatial scale) is often above average in aphantasics, while object imagery is at floor"

Source: Pearson & Keogh, Bainbridge, Spagna and others (e.g., Bainbridge et al., 2021; Pounder et al., 2022; Knight, Milton & Zeman, 2022); Kay, Keogh & Pearson (2024), Consciousness and Cognition, on mental rotation

Supporting accounts

"Spatial imagery (specifically object rotation tasks, as seen here) and visual mental imagery are not necessarily directly linked in the way you’re asking about. Most studies on this have found that aphantasics don’t exhibit statistically significant impairments compared to non-aphants on spatial imagery tasks" 2025 · t1_mdcyf37 ↗

"Spatial and visual mental representation (while related) are not the same, it's believed that aphantasia is a lack of visual but not spatial representation. In fact many aphantasics outperform those with visual mental imagery on spatial tasks." 2021 · t1_hmefzjh ↗

"I have full aphantasia but I can rotate objects in my head. Not visually, but spatially, which for me seems to be an independent skill." 2024 · t1_lj7h8tn ↗

"Spatial sense allows us to do that without seeing it. It is completely separate from visualization. Multiple studies have found that aphants perform about the same as controls on mental rotation tests." 2024 · t3_1eq3490 ↗

Contradicting / qualifying accounts

"I genuinely have no clue how people are able to mentally rotate objects (maybe I could do it with effort for a simple object, but there’s no chance for a complex one). I think I have a lesser known type of aphantasia (spatial aphantasia). I think the spatial part is probably more debilitating than the visual part." 2025 · t1_myp7104 ↗

A subset of aphants self-identify as having "spatial aphantasia" too — a phenotype the literature acknowledges but that is rarer than the preserved-spatial pattern.

Extending observations

"Spatial rotation tasks do not rely on images." 2025 · t1_myp2xl4 ↗

"Verbal strategies → reasoning through words, categories, and similarities." 2025 · t1_ncn7p2z ↗

These describe the analytic / first-person-embodied / verbal strategies that Kay, Keogh & Pearson (2024) and the Boere et al. (2025) EEG study propose account for the slower-but-equally-accurate aphantasic profile.

Claim 5: "Acquired aphantasia (MX, PL518, post-stroke, post-illness, post-stem-cell-transplant): often associated with focal lesions in left fusiform / lingual gyrus or bilateral PCA territory"

Source: Zeman, Della Sala et al. (2010), Neuropsychologia, 48, 145; Thorudottir et al. (2020), Brain Sciences, 10:59 (PL518); Spagna et al. (2025) lesion network mapping; congenital/acquired distinction throughout

Supporting accounts

"Aphantasia is both a congenital and developmental condition. The majority of people have aphantasia since birth, sometimes referred to as “lifelong aphantasia.” There's ongoing research into possible hereditary factors (TBD). But aphantasia can also result from a stroke or brain injury. The original case (that led to the naming of aphantasia) was an acquired case of aphantasia. 'Patient MX' lost the ability to visualize after a stroke." 2023 · t1_k3exc80 ↗

"I acquired it after my brain didn’t receive enough oxygen for a bit too long. So it certainly can be acquired as before that I had very vivid mental imagery." 2021 · t1_gzm28sy ↗

"Acquired aphantasia is very rare. Maybe less than 3% of aphants acquire it after birth. The current theory is that some event has to happen. Physical trauma such as stroke, TBIs and surgery are known causes. Psychological trauma along with depression and depersonalization are also known causes. There is even a paper saying that COVID-19 caused a case." 2023 · t3_164yno5 ↗

"Yes, but it is typically acquired after a traumatic brain injury or something similar, I think trauma could also cause it. My father in law lost his ability to visualize after a TBI" 2023 · t1_joloq11 ↗

Contradicting / qualifying accounts

"it isn't for life long asphants, but NIH and other sites say brain injury and stroke are the usual causes of acquired aphantasia, which I have. But I have acquired aphantasia and as far as I know, neither applies in my case." 2025 · t1_mtd1v11 ↗

This qualifies rather than contradicts: acquired aphantasia without identifiable focal lesion is exactly the open subset the Spagna et al. lesion-network mapping work is designed to capture (network-level convergence onto the FIN even when no single lesion is visible on MRI).

Extending observations

"This is always important to point out, because most people here are congenital aphants, they are like they are from birth - thus have no comparison." 2025 · t1_mtmvknm ↗

The community itself enforces the congenital/acquired distinction central to section 9 of the research note.

Claim 6: "Often preserved visual dreaming (in ~50-70% per Zeman group surveys)"

Source: Zeman, Dewar & Della Sala (2015), Cortex, 73, 378-380, "Lives without imagery - Congenital aphantasia"; reaffirmed throughout the Zeman group's surveys

Supporting accounts

"In one study of almost 2000 aphants, 63.4% reported having visual (not necessarily lucid) dreams. Top researchers have recently clarified that voluntary visualization requires “full wakefulness” and they stated that \"imagery in dreams or on the verge of sleep is often preserved.\"" 2024 · t1_lswcx2j ↗

"Despite their substantial (9/21) or complete (12/21) deficit in voluntary visual imagery, as judged by the VVIQ, the majority of participants described involuntary imagery. This could occur during wakefulness, usually in the form of ‘flashes’ (10/21) and/or during dreams (17/21)." 2021 · t1_hjwz53g ↗

"Many people with aphantasia still have visual/sensory dreams, it's not unusual at all. Aphantasia is only about conscious voluntary recall, your dreams have no bearing on it at all." 2021 · t1_h7ue2u4 ↗

"Yes. Extremely visual color dreams. Zero waking imagery." 2018 · t1_e3zm11x ↗

Contradicting / qualifying accounts

"I cannot visualize while dreaming at all." 2021 · t1_hjwz53g ↗

The same Reddit thread that quotes Zeman et al. also includes lay reports of fully imageless dreaming — consistent with the ~30-50% of the literature's estimate who do not report visual dreams.

Extending observations

"Dreams are the only time I can visualize anything, they’re always so vivid and also just weird honestly." 2020 · t1_fzo035k ↗

A direct phenomenal description of the wakefulness-gates-imagery distinction cited in Claim 6 — vivid in-dream visuals that cannot be re-summoned voluntarily upon waking. The DMN-vs-frontoparietal-imagery network split (Section 3 of the research note) is exactly the dissociation this account describes.

Synthesis

For every neuroscientific claim where a phenomenal correlate exists, r/Aphantasia accounts confirm the predicted experience: flat reactions to written horror but normal reactions to scary images (Wicken et al. 2021), null pupil responses to imagined brightness (Kay et al. 2022), preserved spatial / mental rotation despite no object imagery (Bainbridge et al. 2021; Kay et al. 2024), acquired-after-stroke onset (MX, PL518), and preserved visual dreaming in roughly two-thirds of aphants (Zeman et al. 2015). The lay corpus also spontaneously articulates a frontoparietal-to-visual-cortex disconnection model — in lay words, "the prefrontal cortex can't get through to the visual cortex" — that maps cleanly onto Milton/Zeman 2021 and Liu/Bartolomeo 2025. Where the neuroscience is specifically about integration (FIN-frontoparietal coupling, hippocampus-occipital negative coupling, P300 amplitude), Reddit cannot verify the substrate but reliably reports the dissociations that those substrates predict — dreaming without waking imagery, semantic-but-not-emotional memory, slow-but-accurate rotation. The lived experience is in fact richer than the fMRI in one place: the routine spontaneous reports of "spatial aphantasia" and of multi-sensory aphants whose verbal/auditory imagery is also absent suggest sub-phenotypes the imaging literature is only just beginning to map.