How Did We Miss Motor Differences in Autism for So Long?

By Heather M. Burroughs, Parent & Professional.

Given that, it raises an important question: why are autistic people still routinely assessed as though motor ability has little or no bearing on what they can understand, communicate, or learn?

The implications of that gap are far-reaching, affecting education, therapy, communication access, employment, independence, and overall quality of life.

The 60-Second Version

Motor differences are common in autism, yet only a small percentage of autistic people receive a motor-specific diagnosis or intervention.

In other conditions such as stroke, ALS, or Parkinson's disease, clinicians do not assume refusal, lack of effort, or absence of understanding when movement is impaired. Instead, they recognize that the body may be unable to reliably carry out the brain's intent.

However, that same reasoning is often not applied consistently in autism, particularly for nonspeaking autistic people.

This is where the concept of Output–Intention Consistency (OIC) becomes essential. OIC refers to how reliably a person's physical output — speech, pointing, device use, writing, gesture — matches their intended response. When OIC is low, performance becomes inconsistent, not because intention is absent, but because motor execution is unreliable.

As a result, inconsistent performance is frequently misread as lack of willingness or understanding rather than a breakdown in motor consistency. Before drawing conclusions about what someone knows, it is essential to first consider their OIC: what their body can consistently and intentionally produce on demand.

A Conversation Worth Your Time

I recently listened to a compelling episode of The Lighter Side of the Spectrum, hosted by David Kaufer, featuring physiotherapist, researcher, and disability advocate Dr. Antigone Oreopoulos.

Their discussion highlights an area that deserves far more attention: the potential role of motor differences in autism, especially for nonspeaking autistic individuals.

A key principle emerges from their conversation and should inform every assessment. When motor differences affect initiation, planning, coordination, stopping, redirecting movement, pointing, speech, or access to communication tools, they must be considered before drawing conclusions about intelligence, learning potential, or communication ability.

In OIC terms, the question becomes whether a person's output is a reliable reflection of their intention or whether motor variability is disrupting that relationship. In many settings, this step is still overlooked.

We Already Understand This for Other Conditions

If a child presented with similar motor symptoms following a stroke or traumatic brain injury, most professionals would immediately consider a motor explanation. They would not assume the child was choosing not to respond or that they lacked understanding. Instead, they would look for neurological or physical factors that might explain the breakdown in performance.

In autism, however, when a nonspeaking individual cannot point accurately, imitate on command, respond consistently, or reliably use a speech-generating device, the explanation is often framed in cognitive or behavioral terms rather than motor ones. In other words, OIC is often assumed to be stable when it may not be.

This difference in interpretation can significantly alter a person's life trajectory. It influences educational placement, therapy recommendations, communication access, employment opportunities, and whether others believe the person has meaningful thoughts to express. Motor differences therefore do not only affect isolated tasks; they shape the opportunities available for demonstrating knowledge in the first place.

What the Body May Be Trying to Tell Us

Dr. Oreopoulos describes how motor differences can affect initiation, planning, coordination, sequencing, stopping, and shifting movement. These challenges may appear across speech, gestures, eye gaze, handwriting, pointing, self-care, and communication device use.

This reframes the central question. Rather than asking only whether a person can perform a task, we also need to ask what might be interfering with the body's ability to produce consistent output aligned with intention — that is, their OIC.

Many assessments focus on what a person can produce on demand, but that is not always equivalent to what they understand. A person may comprehend instructions, know the correct answer, or recognize the right choice while still being unable to consistently produce the expected motor response.

When motor planning is involved, performance may reflect output variability rather than knowledge variability. That distinction has significant downstream consequences.

Signs Families Often Notice First

Whole-body apraxia does not always present in obvious ways. More often, it appears as inconsistency in OIC, which can easily be misinterpreted. For example, a person may:

• Smile spontaneously but be unable to smile when asked
• Wave naturally but struggle to wave on command
• Use a preferred app easily but have difficulty with basic tools like zippers or utensils
• Demonstrate a skill during play but not during formal evaluation
• Know the location of an object but struggle to point to it when asked
• Wipe the wrong area of the face after being told where food remains
• Repeat familiar words or AAC selections that do not match intended meaning
• Require rhythm, modeling, extra time, or support to initiate movement
• Begin an action but have difficulty stopping or shifting to the next step

These patterns may reflect reduced OIC — a genuine disconnect between intention and the body's ability to execute that intention consistently.

The "Could This Be Apraxia?" resource at EvidenceBasedMethods.org helps families explore whether everyday observations may reflect motor-planning differences rather than lack of understanding or motivation.

In many cases, families notice this discrepancy long before it is formally recognized. They observe moments of clear understanding followed by sudden breakdowns in output when performance is required on demand. That pattern deserves careful consideration rather than dismissal.

Sensory Regulation Is Part of the Picture

Movement does not occur in isolation from the rest of the nervous system. Sensory processing, anxiety, regulation, visual demands, social expectations, and environmental complexity can all influence OIC.

For example, busy environments, unexpected sounds, visual clutter, rapid instructions, or performance pressure may significantly reduce a person's ability to coordinate intentional movement — even when they understand what is being asked. In such cases, OIC may drop sharply depending on context, making ability appear inconsistent or absent when it is actually context-dependent.

This becomes especially important when selecting communication systems. Even highly advanced devices may be inaccessible if a person cannot consistently coordinate vision, movement, timing, language, and regulation simultaneously.

When a communication system is not effective, the guiding question should shift. Instead of asking whether the person can communicate, we should ask whether the system supports their OIC — allowing intention to translate into reliable output.

Six Questions Professionals Should Ask First

Before concluding that someone cannot understand, learn, or communicate meaningfully, it is important to consider:

• What motor demands does this task require?
• Is the movement familiar or novel?
• Is the person regulated enough to access the skill at this moment?
• Are sensory, visual, environmental, or social factors interfering with OIC?
• Does performance improve with modeling, rhythm, extra time, or reduced pressure?
• Is this assessment measuring knowledge, or primarily measuring motor output consistency?

These questions should precede decisions about placement, therapy, or conclusions about ability.

We Know Better Now

Twenty years ago, the field had far less understanding of motor differences, whole-body apraxia, sensory regulation, and their relationship to communication. Today, that knowledge is much more developed.

This does not mean that every autistic person has significant motor challenges, nor that all communication differences are motor-based. It does mean that OIC and motor differences should no longer be overlooked when evaluating ability.

When professionals ask more precise questions, they make more accurate interpretations. This, in turn, allows individuals better opportunities to demonstrate knowledge, access communication, and participate fully in their own lives.

The central question is no longer whether motor differences matter. It is whether we are willing to let that understanding meaningfully change how we assess, teach, support, and communicate. Every assumption shapes opportunity.

If motor differences may be part of the picture, then OIC must be considered at the beginning of evaluation — not as a secondary explanation after years of misunderstanding.

Watch the featured clip, then listen to the full episode of David Kaufer's The Lighter Side of the Spectrum with Dr. Antigone Oreopoulos. Whether you are a parent, educator, therapist, physician, psychologist, or self-advocate, the conversation may shift how you think about autism, communication, and human potential.

If this article resonates, consider sharing it with someone who may need to reconsider a long-held assumption: Maybe the person understands. And maybe the body is what is making that understanding difficult to show.