The Unseen Mind — a guide to aphantasia and SDAM

1. What these conditions actually are

Aphantasia is the inability — or severely reduced ability — to form voluntary mental imagery. Most people, when asked to picture their grandmother’s face or the front door of the house they grew up in, produce something they would call a picture. Some of us do not. The screen stays blank. There is nothing to describe.

The word was coined in 2015 by Adam Zeman and colleagues at the University of Exeter, after a patient asked them why he had lost the ability to picture anything after a heart procedure. ^[1] Estimates now put the lifelong (congenital) form at somewhere between 2% and 5% of the population, depending on where you draw the line on the questionnaires. Under the strictest cut-offs the figure is closer to 1%. ^[2]

Aphantasia is not a single thing. Some people have no visual imagery but perfectly normal imagery in other senses: they cannot picture a face, but they can hear a song in their head, or imagine the smell of coffee, or feel the texture of a fabric. Others have what researchers now call multi-sensory aphantasia — no imagery in any modality at all. Spatial reasoning, oddly, is usually untouched: people with aphantasia navigate cities, read maps, and solve rotation puzzles just as well as everyone else. ^[3] The screen is blank, but something underneath the screen still knows where things are.

Severely Deficient Autobiographical Memory — SDAM — is a separate condition, first described in a 2015 paper out of the Rotman Research Institute in Toronto. ^[4] A person with SDAM remembers facts about their own life — where they grew up, who their family is, what school they went to — but cannot re-experience the events those facts describe. There is no mental time-travel back to the wedding, the funeral, the first day, the last evening. The knowledge persists. The re-living does not.

The two conditions overlap but are not the same thing. You can have vivid mental imagery and still have SDAM. You can have aphantasia and still re-experience your past vividly. What is becoming clear, though, is that the two often co-occur — often enough that a meaningful share of the people reading this sentence will recognise both. ^[5]

Neither is a disorder in the clinical sense. Neither is in the DSM or the ICD. There is no deficit to treat, no therapy to prescribe, no medication to take. There is only — and this is why this site exists — a quiet, common, largely unnamed way of being, that until very recently had no word for itself. We are writing one into the language.

2. The research, honestly

Aphantasia is ten years old as a named phenomenon. ^[7] SDAM is a bit younger, though the cases that prompted it go back further. That is not long. Half of what is “known” today will be refined or overturned within the decade. This section is a snapshot, not a settlement.

What the neuroimaging is starting to say

In 2025 a French group led by Jianghao Liu and Paolo Bartolomeo proposed that aphantasia is best understood as a functional disconnection between regions of the brain that would normally cooperate to produce mental imagery — roughly, frontal-parietal control regions and the visual cortex. ^[6] The imagery machinery is physically present in an aphantasic brain. The conductor does not call on it.

For SDAM, a recurring finding is reduced hippocampal activity during attempts to recall specific autobiographical episodes. ^[5] The hippocampus is the region most associated with stitching episodic memories back into a re-livable whole. In SDAM it is not absent; it is quieter, or reached less readily, when the task is remember the day, not the fact about the day.

The honest caveat: these findings are correlational. They describe the brain of a person with aphantasia or SDAM while they attempt a task. They do not (yet) explain why that brain is organised this way, whether it is genetic, how early it settles, or whether the organisation can be changed. All of those remain open questions.

Subtypes and heterogeneity

The earliest framing of aphantasia was binary: imagery or no imagery. That has not survived contact with the data. There are people with no visual imagery but rich auditory imagery. People with no voluntary imagery but occasional involuntary flashes on falling asleep. People who dream in pictures but cannot voluntarily produce them while awake. ^[2] Whatever the underlying mechanism is, it is not one switch.

Something similar is true for SDAM. Some people retain the semantic scaffolding of their lives clearly — they can tell you their whole chronology — but have no re-entry point. Others have episodes that surface unpredictably and are usually tied to strong external cues: a photo, a smell, a specific place. What has not emerged is a clean set of subtypes you can place yourself into.

What is not yet established

• A genetic story. There are suggestive family patterns in the data but no confirmed gene.
• A developmental story. We do not know when in childhood these patterns settle.
• A treatment story. Nothing has been shown to reliably produce mental imagery in a person who does not have it. The training programmes advertised online do not have the evidence behind them.
• A clinical definition. Neither condition is in the DSM-5 or ICD-11. There are no accepted diagnostic cut-offs beyond the VVIQ and the SAM, which are self-report questionnaires.

We write this section sparingly on purpose. It is genuinely a frontier.

3. What it is like

4. How you tell (and how to talk to a GP)

There are two self-report questionnaires that anchor most of the field.

The VVIQ — Vividness of Visual Imagery Questionnaire. Sixteen items. You are asked to picture something — a relative’s face, a sunrise, a shop you know — and rate how vivid the image is on a five-point scale, from “perfectly clear, as vivid as normal vision” down to “no image at all”. People who score at the bottom on most items are the population the aphantasia research is about. The VVIQ is free; you can take it in ten minutes. See the resources page for a current link.

The SAM — Survey of Autobiographical Memory. Longer; twenty-six items across four subscales. The subscale that matters most for SDAM is Episodic, which asks how much you can mentally re-experience past events. A consistently low score on Episodic, with normal or high scores on the Semantic subscale, is the SDAM signature.

Neither questionnaire diagnoses. Both are evidence, not a verdict. The research literature uses them as starting points, not finish lines.

What a UK reader might actually say to a GP

Most UK GPs have not heard of either condition. That is not a failing — the research is new, the training has not caught up. You are not going into the appointment expecting a diagnosis, a referral, or a treatment; there is no clinical pathway for aphantasia or SDAM in the NHS, and there is nothing to treat. What most people are actually after is the conversation — a note on the record, confirmation they are not misremembering themselves, sometimes reassurance that nothing is wrong.

A straightforward script, which you are welcome to lift verbatim:

Swap in SDAM and the SAM questionnaire if that is the one that describes you. Most GPs, faced with this framing, will make a note and move on. A curious GP might ask to look the condition up, which is fine and useful. An occasional GP may push back — “is it really a thing?” — and you can point them at the Zeman group at Exeter, which is the main UK academic home for the research.

You do not need a diagnosis. There is nothing to be diagnosed out of. What you may want is the record, and perhaps a conversation with someone who now knows the name for what they are living with.

5. What it is not

A lot of people arrive at this site convinced they are in worse shape than they are, because the internet has handed them a more frightening word for their experience. Equally, some arrive convinced they are fine when actually something else is going on. This section is here to draw the lines.

It is not brain damage

Most aphantasia is congenital — you were born like this, you always have been. A small subset of cases follow a specific event: a head injury, a stroke, a heart procedure. Those are called acquired aphantasia, and they are a distinct clinical situation warranting proper medical follow-up. If you noticed that your imagery disappeared suddenly, or around a specific illness, see a GP.

It is not early dementia

People with SDAM sometimes worry about this, especially in their fifties and sixties. SDAM is lifelong. It has always been this way for you. Dementia is a change — a shift from a higher baseline toward a lower one. If your autobiographical memory has been flat since childhood, you do not have dementia. If it has recently got worse, see a GP.

It is not the same as having a poor memory

People with SDAM often have perfectly good memory in most respects — facts, names, routes, conversations. What they do not have is the re-living of episodes. That is a very specific shape of forgetting that is easy to mistake for general forgetfulness, and easy for other people to mistake for not caring.

It is not trauma-related dissociation

There is overlap in the felt experience — a sense of not being able to reach the past. But dissociation is, in most framings, a response to specific events, often reversible, often situational. SDAM is a baseline pattern across the whole life. The two can also co-occur. If you suspect you have both, the trauma piece is the one that does respond to therapy; go to that door first.

It is not a disorder

Neither condition appears in the DSM-5 or the ICD-11. There is a way a brain can be configured, which is more common than any of us realised until recently, and which lacks a name in most languages. That is not the same as a clinical condition, and calling it one would be inaccurate.

Not a disorder is not the same thing as not sometimes hard. People arrive at these names carrying real grief, real frustration, and sometimes the long-standing sense that something in how they think did not match what the world expected of them. All of that is valid and none of it is undone by the research being clear that aphantasia and SDAM are not pathologies. The point of insisting the medical label is wrong is not to minimise the experience; it is to keep you from spending your energy on fixing something that cannot be fixed and does not need fixing.

It is not something to be cured

The internet is busy with training programmes, supplements, apps, and visualisation courses claiming to restore mental imagery. As of 2026, none has evidence behind it meeting any reasonable bar. Be suspicious. If someone is selling you imagery, they probably are not giving you any.

6. Living with it

Much of what follows is lived wisdom rather than research — a collection of strategies that people in the forum and in the literature have landed on over time. Treat it as a starting list, not a prescription.

External memory as a first-class habit

People with SDAM often develop, unbidden, a heavy reliance on external memory systems: photos, journals, calendars with notes, voice memos after conversations, a partner whose role includes “holding the story of us”. If this is you, you are not overcompensating; you are doing what an unaided mind cannot. The right frame is not I am bad at remembering; it is I have offloaded the remembering to a system that works.

Things people tend to do:

• Photos as memory, not aesthetic. Take a lot of them. Write what mattered into the caption or file metadata the same day. A photo without a caption, for an SDAM person, is often just a photo.
• A one-line-a-day journal. Enough to hang a memory on, not so much that you stop keeping it. The habit is the point.
• Voice memos after consequential conversations. Five minutes, while it is fresh. You are not recording the other person — you are recording yourself, what you said, what they said, what you agreed.
• A shared note for the relationship. Decisions, in-jokes, promises. It will feel unromantic. It is unusually romantic.

What external memory cannot do

Photos and notes do not give you back the re-living. They give you the scaffolding you can build a re-telling on. That is a different thing, and it is worth being honest with yourself about the gap.

For relationships

People you are close to may find this harder to absorb than you do. The absence of a picture of their face when you think of them, the inability to play back the holiday you just shared, the fact that you may not miss them the way they miss you — these can land as rejection even after they have been explained. Keep explaining. Some lines help:

See the family & partners page for a longer version of this material.

For work

Written reflection does the work that mental rehearsal does for everyone else. If you need to remember what someone said in a meeting, write it down while they are saying it. If you need to prepare for a difficult conversation, draft it. The aphantasic and SDAM professional is often the most-written person in the room, and the habit is quietly why.

7. For the people around you

Short — most of this material lives on the family & partners page. Draft pending.

8. Where to go next

UK research groups actively recruiting

• The University of Exeter, led by Adam Zeman’s group, is the UK home of the aphantasia research. They have run the Eye’s Mind project and continue to recruit participants. Current study information is linked from the resources page.
• The University of Glasgow, led by Fiona Macpherson, runs the wider consciousness and imagination research programme that includes imagery extremes.
• For SDAM specifically, the main site is still the Rotman Research Institute in Toronto. They accept international participants.

The community (opening later in 2026)

A UK-focused forum is in preparation — deliberately small and moderated, aimed at thoughtful written peer conversation rather than fast-moving chat. It is not live yet; the forum page explains the plan and lets you be told when it opens.

The research tracker

A monthly research tracker translates new peer-reviewed papers into plain English, with citations. If you want the field delivered without wading through journals, that is the place.

The newsletter

One email a month. What landed on the site. What shifted in the research. Nothing else. Double opt-in; export your address any time.

Further reading

• Zeman, A. (2024), Aphantasia and hyperphantasia: exploring imagery vividness extremes, Trends in Cognitive Sciences — a long-form overview pitched at roughly the right level for a non-specialist reader.
• The references at the foot of this page are the primary literature the guide has drawn from.
• Reddit’s r/Aphantasia and r/SDAM are useful for pattern-recognition — you will see yourself in other people’s posts — but they are not evidence.

If you have read this far and something in here felt like it was written for you, the newsletter is the one door most worth walking through today. The forum opens later in 2026 and newsletter subscribers are told first.