The forty-second forgetting
You stand up to get a glass of water, and on the way to the kitchen you remember you need to send an email. By the time you get back to your desk, the email is gone. You sit down, look at your screen, and feel that very specific flavour of frustration: I knew this thirty seconds ago. Where did it go?
If you have ADHD, this happens to you constantly. It is not a character flaw. It is a measurable difference in working memory.
What working memory actually is
Working memory is the cognitive bench you use to hold a thought long enough to do something with it. Reading a phone number from one screen and dialling it on another. Holding "I need to email Mara" in your head while finishing the sentence you were already typing. Keeping the next item in a sequence available while you do the current one.
It is not the same as long-term memory. You can have an excellent memory for facts and faces and still have unreliable working memory. Working memory is specifically the bridge between intention and action.
In adult ADHD, this bridge is shorter and less reliable than average. Russell Barkley's research positions deficits in working memory as one of the central executive functions impacted by ADHD, alongside response inhibition and self-regulation. More recent meta-analyses confirm that working memory tasks are one of the most consistent diagnostic differences between adult ADHD groups and controls.
The practical effect is that thoughts slip out before you can use them. The task you "definitely won't forget" gets forgotten, not because it wasn't important, but because something else demanded your attention before your brain finished writing the original thought to durable storage.
Why this is not a character problem
The most damaging part of working memory difficulty in adult ADHD is not the forgetting itself. It is the story you build around the forgetting.
If you grew up undiagnosed, you probably learned to interpret these gaps as moral failure. You forgot, so you must not have cared enough. You did not finish the thing, so you must be lazy. You said you would do it and then did not, so you must be unreliable.
None of those interpretations match the actual mechanism. The mechanism is: a thought arrived, your brain did not have enough working memory to hold it long enough to externalise it, and it left. Caring more would not have changed the outcome. Trying harder would not have changed the outcome. The thought was already gone before willpower could be applied to it.
This matters because the way you treat yourself about forgetting affects how often you build systems that compensate for it. People who think "I'm just bad at this" are less likely to use a capture system. People who think "my working memory is unreliable, so I need an external one" are more likely to use a capture system, and to keep using it.
The forty-second window
There is a rough rule that comes out of working memory research: a thought you do not externalise within roughly forty seconds is at high risk of being lost when you switch contexts. Forty seconds is not a hard limit. It varies by person and load. But it is a useful approximation for the question of when a thought needs to leave your head.
Most capture systems fail at this window. Opening an app, deciding which list it goes on, naming the task, and tagging it takes longer than the window. By the time you have completed the capture overhead, the thing you actually wanted to capture has either drifted or been displaced.
The most reliable workaround is to remove all of that overhead. The thought leaves your head before any decision is required. Sorting and prioritising happen later, not at the moment of capture.
Voice as a working-memory prosthetic
For adults with ADHD, voice capture is the closest thing currently available to a working-memory extension. Pressing one button and speaking is fast enough to fit inside the forty-second window even when the thought is complex or arrives in fragments. There is no decision about category, no naming, no prioritising. Just the act of saying it out loud.
This is the design principle behind Sukima. You hold the button, you speak whatever is in your head, and the thought is gone from your working memory and into a system that will hold it for you. The AI does the categorising and prioritising afterward, when your brain is no longer trying to hold the thought.
The shift this produces is hard to describe to someone whose working memory is reliable. The mental quiet that comes from knowing every loose thought is captured, with no required decision in the moment, is not the same kind of quiet you get from a good to-do list. It is more fundamental. The background hum of "do not forget, do not forget, do not forget" gets to stop.
What this looks like in practice
A normal day for an ADHD adult contains maybe twenty to forty captureable thoughts. Things to email, things to fix, things to look up, things to ask, things to remember at a specific time, things to remember at a vague future time. Without an external system, most of these are forgotten and then either rediscovered later in worse circumstances or never recovered at all.
With a working-memory prosthetic that fits inside the forty-second window, almost all of them get captured. They do not all need to be acted on, and many will be deprioritised by the system itself once you see them written down. But none of them get lost.
The downstream effect is that you stop having the experience of "I know I was supposed to do something today but I cannot remember what." That experience is one of the more demoralising parts of ADHD adulthood. Removing it has consequences beyond productivity.
Working memory is not something you can train
A note on the productivity advice that says you can improve your working memory through brain training games or mental discipline. The research on this is not encouraging. Working memory capacity appears to be relatively stable in adulthood, and what training improves is performance on the specific training tasks, not general working memory in real-world situations.
What does improve is the gap between what your working memory can hold and what your life requires it to hold, when you stop trying to close that gap with willpower and start closing it with external systems. Tools that act as a working-memory extension do not improve your working memory. They make your working memory limit irrelevant for most of the situations where it currently fails you.
This is not a workaround. It is the whole game.
References
Barkley, R.A. ADHD and the Nature of Self-Control. Guilford Press, 1997.
Cortese et al. Cognitive Impairment in Adult ADHD. PMC, 2025.
Baddeley, A. Working memory: theories, models, and controversies. Annual Review of Psychology, 2012.
Sukima is on the App Store today. If working memory is the thing your brain keeps dropping, this was built for exactly that.