Part 5 of Prediction, Control, and the Regulating Mind

The Hard Case: Autism and Stimming

Dr. Greg Moody · August 17, 2026 · Updated September 12, 2026

This is where I worked the model out first, and it's the application I hold with the least confidence.

A framework earns its keep on hard cases. Autistic stimming is the hardest one I know, because the behavior is common, the accounts of it conflict, the intervention history is genuinely ugly, and the people it describes are right there and able to say whether the description fits.

Everything below is a hypothesis about organization. Nothing in it should change what anyone does tomorrow, and the last section says so in plain terms.

What Stimming Is For

Kapp and colleagues interviewed 32 autistic adults about it, and the finding is directional (Kapp et al., 2019). Stimming responded to intense emotion in both directions. Some participants stimmed when anxious or distressed. Others when excited or happy.

As Rebecca put it:

"[s]timming is just a release of any high emotion, so really anxious, really agitated, really happy, really excited, just any high emotion, that's when I stim."

The valence varied across participants. The potency of the state was what stayed constant. Two participants described happy hand flapping as hands open and arms out, unlike the tighter, closer movement of distress. Same behavior, different topography by valence.

Sinead's account of childhood spinning isn't a description of soothing at all:

"I remember as a child spinning all the time and loving spinning and loving swinging and feeling that movement all the time, but then I also realised that there was a point where it wasn't acceptable to be spinning anymore … so it actually still feels glorious if there's nobody around and I can skip or I can spin and it's like I'm breaking the rules."

Two words get used interchangeably for what stimming does, and they aren't equivalent. Self-soothing is an observer's inference, what the behavior looks like it's for, from outside, in a person who appears distressed. Self-regulation is closer to what autistic people report, and broader in a way that matters.

I'll own my share of that first one. I spent years describing this behavior with a word nobody had ever tested against what the person doing the behavior reported. The label traveled on how plausible it sounded from across the room.

A behavior that occurs as reliably in pleasure as in distress is doing something other than soothing. It's bringing an aroused system back toward a workable range, from whichever side it departed.

"Self-stimulatory behaviour" entered the literature through behavior-analytic research on autistic children, where it named repetitive behavior that appeared to compete with instruction (Lovaas et al., 1971). If a behavior is reinforced by its own sensory feedback and competes with learning, the intervention logic points straight at extinction. Generations of autistic children were taught to sit on their hands.

"Stimming" is the community's reclamation of that term, and the shortening isn't cosmetic. It drops the pathologizing frame and keeps the descriptive content.

Prayer May Be Doing the Same Job

More than four in ten U.S. adults (44%) say they pray every day, according to Pew's most recent national survey of religion (Pew Research Center, 2025). Plenty of that prayer runs on repetition: beads counted, a phrase said over and over, a body rocking in time.

Bernardi and colleagues recorded 23 adults reciting the rosary in Latin and a yoga mantra, and both slowed breathing to almost exactly six breaths a minute while baroreflex sensitivity went up (Bernardi et al., 2001). That's a cardiovascular result, and the study didn't ask anyone whether they felt calmer.

Six breaths a minute is slow breathing, and a meta-analysis of 223 studies found slow breathing raises vagally mediated heart rate variability during a session, right after one, and across multi-session programs (Laborde et al., 2022).

Anxiety itself seems to produce repetition. Lang and colleagues induced anxiety in the lab and watched hand movements get more repetitive and more rigid, with the change tracking heart rate (Lang et al., 2015). Karl and Fischer found that stressed participants who moved more repetitively showed somewhat larger drops in heart rate, although that result was marginal and their formal ritual condition didn't beat the control group (Karl & Fischer, 2018).

In Mauritius, people who performed their usual temple ritual after a stressful task reported less anxiety and showed lower physiological anxiety than people who sat and relaxed (Lang et al., 2020). A later pre-registered study with 268 students found the effect slight overall, and clearest in the most anxious half of the sample (Lang et al., 2022).

Boyer and Liénard's account of ritualized behavior adds a downside: repetition can give temporary relief from intrusive thoughts and strengthen them over the long run (Boyer & Liénard, 2006).

Picture a grandparent working through rosary beads in the back pew, and a kid flapping their hands in a hallway. The repetition looks the same, and the autistic adults Kapp interviewed describe their stims as a way of regulating high emotion, which is the same general job (Kapp et al., 2019). The grandparent gets called devout, while the kid is more likely to get called a symptom and handed a behavior plan.

Link and Phelan put labeling first in how stigma forms: people single out a human difference, label it, and then link the label to negative stereotypes (Link & Phelan, 2001). Sinead, in Kapp's study, describes that from the inside – spinning "actually still feels glorious if there's nobody around" (Kapp et al., 2019).

Put every regulation behavior on one ladder, sorted by cost. The low-cost end holds prayer, mantra, slow breathing, stimming, rocking, exercise, dancing and time inside a special interest. Autistic bloggers describe the same functions under lists, routines, stims, exercise and dancing: a sense of control, recharging, and a reliable way to head off overwhelm (Petty & Cantwell, 2025). Autistic adults interviewed about flow described stimming as one way in, because it creates predictable sensory input that blocks out the overwhelming kind (Wain et al., 2026).

The high-cost end holds behaviors that do the same regulating job and hurt the body doing it. Self-injury is one – the self-injury addendum covers it in clinical terms. Most stims don't injure the body – a lot of the cost may come from how the people around the kid react.

Where do your own habits sit on that ladder (a pen clicked through a meeting, a knee bouncing under the desk, a rosary in a coat pocket)?

What do you do with that? Ask what the stim regulates, and whether a lower-cost version exists, before anyone asks how to stop it. Kapp's participants objected to treatment aimed at eliminating stimming, tried to suppress the stims that hurt them, and the ones who could hold their stims back described it as depleting, effortful work (Kapp et al., 2019).

Autistic adults name masking, the work of suppressing autistic traits, as the reason they give most often for autistic burnout (Raymaker et al., 2020; Mantzalas, Richdale, Adikari, et al., 2022). A conceptual model of burnout risk lists stimming as protective and warns that interventions aimed at eliminating stims can harm mental health (Mantzalas, Richdale, & Dissanayake, 2022).

If the stim hurts the kid (or someone else), look lower on the ladder for something that does the same job. If it doesn't, trying to eliminate it may cost more than it saves (Mantzalas, Richdale, & Dissanayake, 2022). Neither recommendation comes from the control model.

Stimming as a Limit Cycle

Which makes it measurable. If stereotypy is oscillation it should have frequency structure, and that structure should respond to loop parameters rather than to how unpleasant the room is.

Two other features fall out without extra assumptions.

Insistence on sameness. An under-damped loop is fine until something perturbs it. Its vulnerability is the ringing that follows a disturbance. A system that oscillates badly after every perturbation has a rational interest in preventing perturbations. Read that way, insistence on sameness stops looking like rigidity as a trait and starts looking like disturbance avoidance in a system whose recovery is expensive.

Meltdown escalation. Escalation is what an under-damped loop does when the disturbance persists, or when corrections generate new error. A meltdown that ends in exhaustion rather than resolution maps onto instability better than onto emotional intensity.

That distinction is testable, and cheaply. An intensity account predicts response size scales with trigger size. An instability account predicts that past a threshold, response size becomes largely independent of trigger size.

Why More Feedback Can Make Performance Worse

Four observations separate the two accounts, and they lean toward stability.

The eyes-open result. Under overload, closing your eyes removes an input and should reduce distress, so sway should worsen with the eyes closed, as it does in nearly every other population, because vision is stabilizing. Bloomer and colleagues found the group difference more apparent with the eyes open (Bloomer et al., 2025). Adding a feedback channel made it worse. That's what raising loop gain does, and not what removing sensory burden does.

The dynamic-only result. Lidstone and colleagues found the deficit for moving targets and not static ones, with the same display in both (Lidstone et al., 2020). Intensity was constant. The demand on closed-loop tracking was not.

The form of the degradation. Excess power below 0.25 Hz (Lidstone et al., 2020), more periodic reactive adjustments (Mosconi et al., 2015), and reduced entropy with increased regularity (Pettinato et al., 2024; Unruh et al., 2021) all describe output becoming more rhythmically structured. Overload and distraction produce noisier output. Instability produces more structured output, because a limit cycle is highly regular.

Degradation at both extremes. Mosconi and colleagues found worse performance at highly amplified and highly degraded feedback gain (Mosconi et al., 2015). Too much loop gain destabilizes. Too little leaves error uncorrected. An intensity account has no reason to predict that reducing feedback resolution also hurts.

None of this is decisive. Reduced entropy has other explanations, and stability is the more economical reading rather than the proven one. Overload has not been excluded.

How Strong the Evidence Is

The model has not been tested. No study has manipulated observer gain and controller gain independently in autistic participants, measured damping directly, or predicted a treatment response from loop parameters and then confirmed it.

None of the researchers cited above set out to test a gain-and-damping model, and none would necessarily accept this reading of their data.

The specific risk is flexibility. Four free parameters, plus delay and arbitration, can accommodate almost any outcome after the fact.

Sensory intervention works: observer gain. It fails: wrong parameter. Exercise helps: damping. It doesn't: wrong dose.

Each move is individually reasonable and collectively fatal.

The model also doesn't handle hypo-reactivity cleanly. Low registration can be modeled as low gain on a channel, but it can equally reflect attentional allocation, a detection threshold, or competition from a channel currently consuming the available precision. The framework accommodates hypo-reactivity. It doesn't predict it, and that asymmetry is a real weakness.

Something has to decide which loop gets control, and that arbitration has a formal treatment outside the autism literature in the reinforcement learning work on choosing between a fast stored answer and a slow deliberate one (Daw et al., 2005).

What Would Show This Is Wrong

Six more criteria sit alongside it in the full document. Three of them:

If reducing sensory intensity reliably outperformed increasing predictability, the account is wrong, because the model says the problem is loop stability rather than input magnitude.

If repetitive behavior turned out to have no characteristic frequency structure, the oscillation claim collapses. Stereotypy would be repetitive without being periodic, and a limit cycle is nothing if not periodic.

If observer-side and controller-side atypicality never dissociated in real people, the two dials aren't two dials.

These only work as protection if they're treated as commitments rather than as a list. That's the whole reason Part 7 exists.

What a Clinician Can Do with This

Two cautions that have nothing to do with control theory and outrank everything above.

The framing in autism research has moved, unevenly, from a deficit model toward a neurodevelopmental-difference model, in which much of the disability sits in the mismatch between person and environment (Pellicano & den Houting, 2022). That consequence is concrete. Under a deficit model the target of intervention is the person's behavior. Under a difference model the target is the fit. Same assessment, two different plans, and a mechanistic model of stimming can be pressed into service for either one. I intend it for the second.

And Milton's double empathy problem is the corrective worth carrying into any room where this gets discussed: the breakdown in mutual understanding between autistic and non-autistic people runs in both directions, and the clinician is one of the two parties (Milton, 2012).

Any sentence beginning "autistic people are" is a hypothesis to check with the person in front of you. That includes every sentence on this page.

Next, the same three failures, in a business.

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