Foot tapping, leg bouncing, pen clicking, shifting in a chair, rolling something between your fingers. From the outside, all of it can look like the brain has left the building.
But movement can increase when the brain is being asked to do more, which makes the picture a lot less simple than “still = focused, moving = distracted.”
Thinking harder can come with more movement
In adults with ADHD, researchers have found that motor activity can increase during working-memory demands. One study comparing adults with ADHD, generalized anxiety disorder, and healthy controls found that all three groups moved more during working-memory tasks, but the increase was disproportionately larger in the ADHD group. That study is here.
That study doesn’t tell us the movement caused better thinking. It tells us “more thinking” and “more movement” can show up together.
Earlier work in children with ADHD found a related pattern. Higher activity was associated with better working-memory performance for children with ADHD, while the pattern was different in typically developing children. That research is here.
Sometimes the movement may be doing a job
A 2024 study of 70 adults with ADHD measured wrist and ankle movement during an attention-heavy cognitive task. Participants fidgeted more during correct trials, and people with more consistent reaction times showed more fidgeting later in the task.
The researchers described those findings as consistent with the possibility that fidgeting may support arousal and sustained attention. They also left room for other explanations, which is important. This is an association, not proof that everybody should start moving more on purpose.
What you can see doesn’t tell you where attention is
I think that’s part of why fidgeting gets interpreted so quickly. A still body looks attentive from across the room. A bouncing leg looks distracted. Neither observation tells you very much about what the brain is actually doing.
The question I find more useful is whether the movement is happening in the background while the brain stays with the task, or whether the movement itself has become the task.
If you want the adult-attention version of that question, including the personal story that sent me into this research, start with Why Do I Focus Better When My Hands Are Busy?