ADHD and Working Memory: Why Things Can Disappear From Mind
You walk into the kitchen to do something and notice an envelope on the bench. It reminds you that you need to book an appointment, so you reach for your phone before the thought disappears.
There’s a notification waiting. You open it, reply to a message and notice something else you need to check. Several minutes later, you’re doing something completely different, and the original reason you walked into the kitchen has gone.
Sometimes it comes back almost immediately. Sometimes you remember when you return to the room. Sometimes it reappears hours later, when the moment in which you could easily have done something about it has passed.
Experiences like this can be frustrating because they don’t always feel like ordinary forgetting. You knew what you were going to do and the intention was genuinely there. Something else simply entered the picture and, somewhere in the shift, the original thought stopped being available.
Working memory can help explain why.
Working memory is the mind’s temporary workspace
Working memory is the capacity to hold information briefly while you’re using it. It helps you keep the beginning of a sentence in mind while listening to the end, remember the next step while completing the current one, hold onto a question while somebody else is speaking, or carry an instruction with you as you move from one room to another.
It’s sometimes described as a mental notepad, which is useful as long as we don’t imagine the notepad sitting quietly on a desk. Working memory is active. Information is being held, selected, updated and rearranged while new information continues to arrive.
You might be keeping one intention in mind when somebody asks you a question. While answering, another thought occurs to you. Your phone makes a sound, or you notice something else that needs doing. As your attention shifts, what occupies that temporary workspace can shift with it.
The original information hasn’t necessarily been erased from memory. It may simply no longer be active in the mental workspace you’re using right now.
This is different from long-term memory
One of the confusing things about working-memory difficulties is that they can coexist with an excellent memory.
You might remember conversations from years ago in remarkable detail, know the lyrics to songs you haven’t heard since childhood or retain obscure information about subjects that interest you, yet still lose the thing someone asked you to do moments after they said it.
That seems contradictory until we separate different kinds of memory.
Long-term memory allows information to be stored and retrieved over much longer periods. Working memory is concerned with keeping information available while you need to use it now. Remembering a childhood address and remembering why you walked upstairs aren’t really asking the same thing of your memory.
This is why someone can have vivid, detailed long-term memories and still struggle to keep a current intention active while something else is happening.
Sometimes the problem isn’t remembering the information
Imagine someone asks you to send them a document when you get home. You hear the request, understand it and genuinely intend to do it. Later that evening, the conversation suddenly returns to you.
The document.
You haven’t forgotten the request in the ordinary sense. You can remember who asked, what they wanted and perhaps even where you were standing when they asked. What didn’t happen was the intention returning to awareness at the moment when you could act on it.
Researchers use the term prospective memory for remembering to carry out an intention in the future. It’s involved when you need to remember to send a message after a meeting, take something with you when you leave the house, buy something when you reach the shops or make a phone call later in the day.
For that to happen, the information has to do more than remain somewhere in memory. It needs to become available again at a useful moment.
That distinction can explain an experience many people find particularly baffling: I didn’t forget that it mattered. I forgot to do it.
Interruptions can change what the mind is holding
Suppose you’re getting ready to leave the house and remember that you need to take something with you. The intention is active while you’re thinking about it, but then someone asks you a question. While answering, you notice that you haven’t filled your water bottle, so you head to the kitchen. Once there, you see something that needs putting away and deal with it while you’re there.
By the time you reach the front door, the thing you originally meant to take is no longer part of what your mind is actively holding.
There doesn’t need to be a dramatic lapse in memory anywhere in that sequence. Each shift made sense when it happened. The difficulty arose because the original intention needed to remain available while new information continued to arrive and compete for attention.
This is why an apparently simple instruction such as remember to take this with you can contain more mental work than it seems. You aren’t simply being asked to remember something. You’re being asked to keep remembering it while life continues around you.
ADHD can make this mental workspace less reliable
Research comparing adults with and without ADHD has found average differences in working-memory performance. This doesn’t mean every person with ADHD experiences working-memory difficulties in the same way, or that every forgotten intention can be attributed to ADHD. Working memory is one of several executive processes, however, that can help make sense of some familiar ADHD experiences.
An intention may be perfectly clear until attention shifts. You might lose the point you were about to make while listening to somebody else, begin one task and lose track of it after noticing something that needs doing first, or repeatedly reread instructions because parts of what came before aren’t staying available as you move through them.
Sometimes you’re even left with the strange feeling that there was something you needed to remember, without being able to retrieve what it was.
What makes this especially confusing is that the information often returns later. The problem wasn’t necessarily that it was never stored. It simply wasn’t reliably available at the point when you needed it.
“But you remembered when it mattered to you”
Memory is easily interpreted through motivation. If someone repeatedly forgets household tasks but can recall detailed information about an interest, it can look as though they remember what they care about and forget what they don’t. People can come to the same conclusion about themselves: If it really mattered to me, surely I would remember.
But importance doesn’t guarantee that an intention will remain active in working memory or return at exactly the right moment.
You can care deeply about replying to someone and still remember three days later. You can know an appointment matters and forget something you needed to bring. You can genuinely intend to complete a task and have that intention displaced by everything that happens between deciding to do it and reaching the moment of action.
Caring and attention can, of course, influence memory. The important distinction is that forgetting by itself doesn’t tell us how much somebody cared.
The mind may try to keep an intention alive
If you’ve learned that thoughts can disappear, you may already have an elaborate collection of ways to stop that from happening.
Perhaps you repeat something silently until you can write it down, put an object beside the door so you’ll see it before leaving, send yourself messages, leave browser tabs open or set an alarm the moment somebody mentions a future task. You might even put something somewhere deliberately inconvenient because you know you’ll have no choice but to notice it later.
These can look like ordinary habits, but they’re doing something quite sophisticated: moving information outside working memory so your mind doesn’t have to keep it continuously available.
Sometimes these strategies work so well that the underlying difficulty becomes almost invisible. You may not think of yourself as someone who struggles to remember things at all. Instead, you might say, I’m fine as long as I write everything down.
That as long as is worth noticing. The question isn’t simply whether you remembered. It’s also what helped the intention stay available long enough to become action.
Mental load can make the problem more visible
Working memory has limited capacity for everyone, so the demands on it increase when more information needs to be held and coordinated at the same time.
Something that feels manageable on a quiet day may therefore become much harder when life gets busy. You might be preparing dinner while somebody talks to you, keeping an eye on the time, remembering something needed for tomorrow and trying not to forget the washing you put on earlier. None of those tasks is particularly complicated on its own. Together, they create a very different cognitive demand.
An interruption in that situation doesn’t simply add one more item to a list. It can change what is currently occupying the mental workspace, making it easier for an earlier intention to drop out of active awareness.
This is one reason working-memory difficulties can become more noticeable during periods of greater demand. It doesn’t necessarily mean the person has become less capable. Their mind may simply be being asked to keep more things available at once.
Remembering later doesn’t mean you could have remembered earlier
There’s something particularly maddening about forgetting something when it matters and remembering it perfectly when it doesn’t.
You drive past the shop and suddenly remember what you meant to buy. You leave the house and picture the thing still sitting on the kitchen bench. Someone goes home and the question you meant to ask them immediately returns.
Information isn’t retrieved independently of context. Something you see, somewhere you go or another thought can act as a cue that brings an intention back into awareness.
So remembering later doesn’t necessarily mean the information was consciously available earlier and you simply ignored it. Sometimes whatever brought it back wasn’t there yet.
This can look like carelessness from the outside
Working-memory difficulties are largely invisible. Other people don’t see the information slipping out of active awareness; they see what happens afterwards. You didn’t bring the thing they asked for. You lost track halfway through. You forgot to reply.
When this happens repeatedly, it’s easy for those outcomes to acquire explanations such as careless, scattered, unreliable or not listening. Those explanations can become part of how someone understands themselves as well.
Understanding working memory doesn’t mean consequences stop mattering, or that every forgotten responsibility should simply be excused. What it offers is another question to place alongside the outcome: what was the mind being asked to hold while this was happening?
Sometimes that reveals a very different process from the one visible from the outside.
Working memory can also affect conversations
Not every working-memory difficulty involves forgetting a task. Conversation asks the mind to hold and update information continuously. You’re listening to what someone is saying while keeping track of what came before, connecting one idea with another, deciding whether you want to respond and perhaps holding your own thought until there’s an appropriate gap.
That’s a lot of moving information.
You may know the awkward choice that can create when a thought occurs while someone else is speaking. If you keep rehearsing what you want to say so you don’t lose it, you may realise you’ve stopped listening properly. If you let go of the thought so you can give the other person your attention, it may be gone by the time your turn arrives.
For some people, that can contribute to interrupting. The urge to speak immediately may partly reflect the sense that the thought won’t still be available later. Working memory certainly doesn’t explain every interruption, but it shows how several executive processes can meet inside something as ordinary as a conversation.
Reading can place similar demands on working memory
Reading also requires more than recognising individual words. The beginning of a sentence needs to remain available while you reach the end, and one idea needs to stay active long enough to connect with the next.
If attention shifts or information isn’t staying active, you can reach the bottom of a page and realise that very little of what you’ve just read has come with you. So you go back and read it again, sometimes more than once.
This can happen even when you’re perfectly capable of understanding the material. The difficulty may lie in keeping enough of it available at once to build meaning from it.
It’s also not unique to ADHD. Fatigue, stress, anxiety, depression, distraction and many other factors can affect attention and working memory, which is why the individual experience always needs context.
Working-memory difficulties aren’t the same as having a bad memory
The phrase my memory is terrible can become a catch-all explanation for experiences that are actually quite different.
Perhaps your long-term recall is strong and you retain information well once it has been learned. The difficulty may show up primarily when something needs to remain mentally available while another activity is happening, or when an intention needs to return at a particular moment.
That is much more specific than simply being forgetful, and it helps explain why memory can feel so inconsistent. One thing may stay with you effortlessly while another disappears within seconds, not necessarily because one mattered more or because you tried harder, but because the two situations placed different demands on memory.
Recognising this experience doesn’t tell you whether you have ADHD
Almost everyone walks into a room and forgets why sometimes. People lose their train of thought, forget to buy things, become distracted and leave tasks unfinished.
Working memory is also affected by stress, sleep, anxiety, depression, overload and other health conditions, so recognising yourself in these experiences isn’t evidence by itself that you have ADHD.
When ADHD is being considered, clinicians look at the broader developmental pattern: the nature and persistence of relevant symptoms, how they appear across different settings, their effect on functioning and whether other explanations need to be considered.
Working memory can help describe one part of that experience. It isn’t an ADHD test. Its value is in helping us understand what may be happening inside ordinary moments that can otherwise be surprisingly difficult to explain.
Sometimes the most useful question is what helped you remember
We tend to judge memory by its outcome: either you remembered something or you didn’t. But that can make all the support surrounding successful remembering disappear from view.
Perhaps you remembered the appointment because three alerts appeared on your phone. The gift made it to dinner because you put it directly in front of the door. You bought what you needed because you added it to your phone the moment you thought of it. The school form went back because somebody happened to mention it that morning.
Those supports don’t make the outcome less successful. They show how information was kept available, or brought back into awareness, until it reached the moment when you could act on it.
You may have been creating these supports for so long that they barely register as effort. Understanding working memory can make some of that quiet work more visible, and perhaps shift the question from Why can’t I remember something so simple? towards something more useful: What did my mind need to keep available here, and what helped bring it back when I needed it?
A moment to wonder
Think of something you regularly do to make sure an intention doesn't disappear.
Perhaps you write it down immediately, put something where you'll see it, set an alarm, repeat it to yourself, ask someone to remind you or rely on a familiar routine.
You may never have thought of this as supporting memory. It may simply be the way you've learned to get things done.
For now, you might notice what that system allows your mind to stop carrying on its own.
Keep exploring
There’s more to explore across Through the Disconnect, from understanding ADHD and life after diagnosis to masking and making sense of your experience.
References
Australian ADHD Professionals Association. (2022). Australian evidence-based clinical practice guideline for ADHD.
Willcutt, E. G., Doyle, A. E., Nigg, J. T., Faraone, S. V., & Pennington, B. F. (2005). Validity of the executive function theory of attention-deficit/hyperactivity disorder: A meta-analytic review. Biological Psychiatry, 57(11), 1336–1346.
Faraone, S. V., Banaschewski, T., Coghill, D., et al. (2021). The World Federation of ADHD International Consensus Statement: 208 evidence-based conclusions about the disorder. Neuroscience & Biobehavioral Reviews, 128, 789–818.
Center on the Developing Child at Harvard University. Executive Function & Self-Regulation.
Alderson, R. M., Kasper, L. J., Hudec, K. L., & Patros, C. H. G. (2013). Attention-deficit/hyperactivity disorder (ADHD) and working memory in adults: A meta-analytic review. Neuropsychology, 27(3), 287–302.
Kasper, L. J., Alderson, R. M., & Hudec, K. L. (2012). Moderators of working memory deficits in children with attention-deficit/hyperactivity disorder (ADHD): A meta-analytic review. Clinical Psychology Review, 32(7), 605–617.
