Why Do I Doodle, Fidget, and Hum — Stimming and Attention

You are in a meeting that has gone twenty minutes past its scheduled end. Your pen is moving across the corner of your notebook in tight, repetitive spirals. Your left knee is bouncing under the table at a frequency you could not replicate on purpose. At some point in the last few minutes, you started humming a single note under your breath — so quietly that only you can hear it.

You are paying attention. You know this because you could repeat back the last three things the speaker said. But if someone across the table noticed the pen, the knee, the hum, they would assume the opposite. They would assume you had checked out.

This is the paradox at the centre of a set of behaviours that nearly everyone performs and almost nobody understands. Doodling, fidgeting, humming, tapping, rocking, clicking a pen, chewing the inside of your cheek — these are not the body's way of announcing boredom. They are the body's way of keeping the brain online.

What your body is actually doing when you fidget

In 1975, psychologist Sydney Zentall at Purdue University proposed a theory that would take decades to be fully appreciated. Zentall's optimal stimulation theory argued that individuals with ADHD are not over-aroused. They are chronically under-aroused. The hyperactivity, fidgeting, and restlessness that look like excess energy are actually the brain's attempt to generate enough sensory input to reach its biologically determined optimal arousal level.

The theory reframes everything. The child bouncing in their chair is not misbehaving. The adult tapping their foot during a presentation is not disrespectful. Both are running a self-regulation programme — one that operates below conscious awareness, using the body as a signal generator to feed a brain that needs more input than the environment is providing.

Zentall's framework was supported empirically when researchers found that children with ADHD performed better on cognitive tasks when extra-task stimulation was added: background noise during reading, coloured items during visual tasks, music during arithmetic. The brain was not distracted by the additional input. It was regulated by it.

Göran Söderlund and colleagues at Stockholm University extended this idea in 2007 with a study published in the Journal of Child Psychology and Psychiatry. They found that white noise improved cognitive performance in children with ADHD while degrading it in controls. Their Moderate Brain Arousal model proposes that dopamine levels modulate how much external stimulation a brain needs to function optimally. Low tonic dopamine — the neurochemical signature of ADHD — means the threshold for optimal arousal is higher. The brain needs more signal to reach the zone where it works well. Fidgeting manufactures that signal.

"Noise exerted a positive effect on cognitive performance for the ADHD group and deteriorated performance for the control group." — Göran Söderlund, Stockholm University

This is not a niche finding. A meta-analysis by Nigg and colleagues in 2024 replicated the effect in college-aged students: those with ADHD or elevated ADHD traits benefited from white noise, while their neurotypical peers were harmed by it. The under-aroused brain uses noise — including the noise it generates through its own body — as a tool. Stop the tool, and you stop the regulation.

Why doodling helps you remember more, not less

The assumption that doodling signals disengagement was tested directly by Jackie Andrade, a cognitive psychologist at the University of Plymouth, in a study published in Applied Cognitive Psychology in 2009. Andrade asked 40 participants to listen to a rambling, dull telephone message and try to remember specific names and places. Half were given a simple shading task — filling in printed shapes — while listening. The other half just listened.

The doodlers recalled 29 percent more information than the non-doodlers. On average, they remembered 7.5 names and places compared to 5.8 in the control group.

Andrade's proposed mechanism is elegant. During a boring task, the brain's default mode network — the same system we explored in why you zone out during meetings — tends to activate and pull attention inward toward daydreaming. Doodling occupies just enough cognitive resource to suppress the default mode network without consuming the resources needed to process the primary task. It is a cognitive floor, preventing the brain from falling into full disengagement while demanding so little that the main channel stays open.

The finding has a critical nuance. Later research, including a 2023 study published in the Journal of Applied Research in Memory and Cognition, found that doodling did not improve retention during more engaging or complex tasks. The benefit appeared specific to low-stimulation situations where the risk of mind wandering was highest — exactly the conditions under which the under-aroused brain is most likely to lose contact with the environment.

This maps precisely onto Zentall's optimal stimulation framework. Doodling is not a general-purpose cognitive enhancer. It is a compensatory behaviour that kicks in when the environment fails to provide enough stimulation to keep the attentional system engaged. The brain recruits the hand to generate what the lecture hall is not providing.

The neuroscience of fidgeting and working memory

The strongest evidence for fidgeting as cognitive regulation comes from a line of research led by Mark Rapport and Dustin Sarver at the University of Central Florida. In a 2015 study published in the Journal of Abnormal Child Psychology, Sarver, Rapport, and colleagues measured the relationship between gross motor activity and working memory performance in boys aged 8 to 12 — some with ADHD, some typically developing.

The finding inverted decades of clinical assumption. In children with ADHD, higher levels of physical movement during cognitive tasks correlated positively with better working memory performance. In typically developing children, the opposite was true — more movement meant worse performance. The hyperactivity was not impairing cognition. It was compensating for a deficit in the arousal system that supports cognition.

Julie Schweitzer at the UC Davis MIND Institute has extended this work into adults. Her lab's research, published in Frontiers in Psychiatry in 2024, used quantitative motion tracking to measure fidgeting during sustained attention tasks. Adults with ADHD who engaged in what Schweitzer calls intrinsic fidgeting — self-generated, task-irrelevant movement like tapping or shifting in their chair — performed better on cognitive tasks. Critically, the longer the task went on, the greater the benefit of fidgeting. As sustained attention waned and the brain's arousal dropped, fidgeting increased to compensate, and performance was maintained.

The mechanism runs through the reticular activating system, a brainstem network that acts as a volume dial for cortical alertness. Proprioceptive input from movement — the feedback your muscles and joints send to the brain about body position and motion — feeds directly into this system, raising cortical arousal. For a brain with adequate tonic arousal, the additional input is unnecessary and potentially disruptive. For a brain running below its optimal threshold, the input is not a distraction. It is fuel.

Why you hum and what your vagus nerve has to do with it

Humming occupies a different position in the self-regulation landscape. Where fidgeting raises cortical arousal, humming appears to engage the parasympathetic nervous system — the branch of the autonomic system responsible for calming, recovery, and social engagement.

The mechanism centres on the vagus nerve, the longest cranial nerve in the body, running from the brainstem through the throat, heart, lungs, and gut. When you hum, the vibration of the vocal folds creates direct mechanical stimulation of the laryngeal branch of the vagus nerve. Simultaneously, the slow, controlled exhalation that humming requires activates the vagus through the respiratory pathway. The combined effect shifts the autonomic nervous system toward parasympathetic dominance — lower heart rate, reduced cortisol, increased heart rate variability.

A study by Trivedi and colleagues in 2023 found that humming lowered stress markers and increased heart rate variability, a key indicator of autonomic flexibility and resilience. A separate Holter-based study found that humming produced a lower stress index than physical activity, emotional stress, and even sleep.

This explains something that clinical observation has long documented but neuroscience is only now catching up with: many autistic individuals and people with ADHD hum, vocalise, or make repetitive sounds not to annoy the people around them but to regulate a nervous system that is running too hot. Where fidgeting raises the floor of arousal, humming lowers the ceiling of stress. The two behaviours are not the same. They are complementary — different tools in the same self-regulation toolkit, deployed by the body in response to different kinds of dysregulation.

Stimming is not a disorder — it is a regulatory strategy

The clinical term for these behaviours is self-stimulatory behaviour, shortened in common usage to "stimming." For decades, stimming was pathologised — treated as a symptom to be eliminated, particularly in autism. Applied behaviour analysis programmes historically targeted stimming for extinction, training children to suppress hand-flapping, rocking, vocalising, and other repetitive behaviours on the grounds that they were disruptive or socially unacceptable.

The evidence now runs firmly in the opposite direction. Research from Goldsmiths, University of London found that suppressing stimming for social acceptance had a direct negative effect on emotions and cognition. Participants described a stress-sensory-stress cycle: existing stress worsened sensory sensitivity, which increased the need to stim. When social pressure prevented stimming, the cycle intensified rather than resolved. The suppression did not teach regulation. It removed the person's most effective regulatory tool and left nothing in its place.

A 2024 systematic review synthesising approximately 48 studies and 4,000 autistic participants confirmed that camouflaging — which includes suppressing stimming — is a core contributor to autistic burnout, a state characterised by exhaustion, functional loss, and sensory overwhelm. The research identified that environments fostering authentic expression, including the freedom to stim, aided recovery. Environments that demanded suppression accelerated collapse.

Sofia Tancredi and Dor Abrahamson at UC Berkeley published a landmark reframing in Educational Psychology Review in 2024. Their paper, "Stimming as Thinking," argues that self-stimulatory behaviour is not peripheral to cognition but intrinsic to it. Stimming, they propose, maintains the dynamic equilibrium of the cognitive-affective system and, when enabled rather than suppressed, is capable of driving problem-solving and social interaction. The authors present stimming not as a deficit to manage but as an epistemic resource — a way of knowing that operates through the body rather than despite it.

The attention and sensory-motor dimensions

Through the lens of CognitionType's cognitive dimensions, the behaviours grouped under "fidgeting" and "stimming" sit at the intersection of two systems that are rarely considered together: attention and rhythm, and sensory-motor integration.

Attention and rhythm describes the brain's capacity to regulate its own arousal, sustain engagement across tasks of varying demand, and shift smoothly between focused and diffuse processing. When this dimension runs differently — when the arousal baseline is lower, or the regulatory mechanism is less consistent — the brain compensates. It recruits the body. The tapping foot, the spinning pen, the rhythmic knee bounce are all the attentional system's attempts to generate the input it needs to stay in its functional range.

Sensory-motor integration describes how the brain coordinates incoming sensory information with motor output and body awareness. Proprioceptive feedback from movement — the pressure of your feet against the floor, the weight of the pen between your fingers, the rhythm of your own breathing — feeds directly into the systems that regulate arousal, emotional state, and cognitive readiness. When sensory-motor integration is calibrated differently, as it is in many people with ADHD and autism, the brain may need more of this feedback, or different kinds of it, to maintain equilibrium.

The interplay between these two dimensions explains why fidgeting looks different in different people. Someone whose primary difference is in attentional regulation may fidget specifically during cognitively demanding tasks — the movement compensates for low arousal during high-load processing. Someone whose primary difference is in sensory-motor integration may fidget across all contexts — the movement provides a baseline of proprioceptive input that the nervous system requires regardless of task demands. Someone whose emotional regulation system is also under strain may stim most intensely during periods of emotional overwhelm, using rhythmic movement or vocalisation to activate the parasympathetic brake.

Understanding which dimension is driving the behaviour changes what you do about it. A one-size-fits-all approach — give everyone a fidget spinner, or take all fidget spinners away — misses the point entirely.

Why fidget spinners failed and what that tells us

In 2017, fidget spinners were banned from 32 percent of America's 200 largest high schools. The bans came after a wave of classroom disruption that seemed to prove what sceptics had argued: fidget toys are distractions, not tools.

But the research tells a more nuanced story. Paulo Graziano and colleagues at Florida International University published a systematic classroom evaluation in the Journal of Attention Disorders in 2020, studying children with ADHD using fidget spinners in real classrooms. They found that spinner use was associated with poorer attention and increased distracted behaviour. The spinners were not helping.

The critical distinction is between intrinsic and extrinsic fidgeting. Intrinsic fidgeting — the self-generated, often unconscious movement the body produces on its own, like bouncing a knee or tapping a finger — feeds proprioceptive input directly into the arousal system without consuming attentional resources. Extrinsic fidgeting — manipulating a novel, visually interesting external object like a fidget spinner — captures visual attention and engages the motor planning system in ways that compete with the primary task.

Schweitzer's research makes this distinction explicit. The fidgeting that improved cognitive performance in her studies was intrinsic: shifting weight, tapping, rocking. It was rhythmic, repetitive, and required no visual monitoring. A fidget spinner, by contrast, is visually engaging, novel, and socially interesting — precisely the features that make it compete with, rather than support, the attentional system.

The lesson is not that fidgeting does not work. The lesson is that the right kind of fidgeting works for the right kind of brain, and a commercial product marketed as a universal solution was never going to capture that specificity.

What you can do with this knowledge

If you recognise yourself in this article — if you have always doodled, bounced, hummed, chewed, tapped, or rocked, and have spent years trying to suppress these behaviours because someone told you they were rude, distracting, or immature — the research offers a fundamentally different frame.

Stop treating fidgeting as a character flaw. The evidence is clear: for many brains, self-generated movement during cognitive tasks is not a sign of inattention. It is the mechanism by which attention is maintained. Suppressing it does not produce focus. It removes the regulatory tool the brain was using to achieve focus.

Match the strategy to the need. If your fidgeting increases during demanding cognitive work, the driver is likely arousal regulation — your brain needs more sensory input to sustain engagement. Proprioceptive strategies work best: textured objects you can manipulate by touch without looking, resistance bands on chair legs, or simply allowing your body to move. If your stimming increases during emotional overwhelm, the driver is more likely dysregulation — your nervous system needs calming input. Rhythmic vocalisation, deep pressure, or slow repetitive movement may be more effective than high-energy fidgeting.

Know your own profile. The behaviours grouped under "fidgeting" emerge from different cognitive architectures and serve different functions. What your body does, when it does it, and what triggers the behaviour are all clues to which dimensions of your cognitive profile are doing the heavy lifting. CognitionType maps your processing style across seven cognitive dimensions — including attention and rhythm, sensory-motor integration, and emotional regulation — giving you a specific picture of why your body moves the way it does and what strategies will actually support the brain you have, rather than the brain other people assume you should have.

Advocate for environments that allow regulation. The open-plan office that bans headphones, the classroom that demands stillness, the meeting culture that equates eye contact and physical stillness with engagement — these environments are built on an assumption about how attention works that the research does not support. For some brains, stillness is the disruption. Movement is the focus.

Your body knows something your mind has not been told

The pen spiralling across the notebook margin, the knee that will not stop bouncing, the hum that rises without permission — these are not failures of discipline. They are the body's intelligence at work, running a regulation programme that has been operating since before you had language to describe it.

For decades, the instruction was to stop. Sit still. Pay attention. The irony, as the research now makes plain, is that for many brains, sitting still and paying attention are mutually exclusive. The body moves so the mind can stay.

Understanding that — really understanding it, not as permission to be disruptive but as neuroscience that explains your own experience — changes the relationship between you and the body that has been trying to help you all along.

CognitionType is an informational cognitive assessment, not a clinical diagnosis. If you suspect that ADHD, autism, sensory processing differences, or any other condition is affecting your daily functioning, we encourage you to seek formal evaluation from a qualified clinician.