How Can You Tell the Difference Between Avoidance and Inability?

In applied behavior analysis (ABA therapy), one thing parents commonly ask is whether their child is refusing to do a task or whether they don’t have the ability to do it. This distinction between avoidance and inability is crucial for determining how to best support a child with autism spectrum disorder (ASD).

When a child responds to a task by crying, walking away or ignoring the instruction, it can be easy to label the behavior as defiance or stubbornness. However, in neurodiverse children, the why behind the behavior is rarely that simple

Treating an inability as a behavioral refusal can lead to frustration and burnout for the child. At the same time, treating avoidance as an inability can inadvertently stall the child’s progress.

In this article, we’ll explore how to identify the differences between won’t and can’t and how ABA therapy uses data to provide the right kind of support for each.

Key Takeaways

A child’s resistance to a task is not always defiance; it may reflect a real skill or sensory barrier.
Treating inability like refusal can increase frustration, stress, and burnout.
Treating avoidance like inability can unintentionally slow progress and reduce opportunities for growth.
ABA professionals use data, observation, and assessment tools to determine whether the issue is skill, motivation, environment, or sensory input.
The right support depends on the reason behind the behavior: teach the skill when the child can’t, and adjust motivation or task design when the child won’t.

Table Of Contents

Understanding the Gap Between Can’t and Won’t

To understand this important distinction, we look at the two primary drivers of behavior in this context, the “can’t” and the “won’t.”

The can’t, or an inability to do something, occurs when a child lacks the prerequisite skills, motor planning or cognitive processing to complete a task. Even if you offered them their favorite treat, they physically or mentally could not perform the action.

The won’t, or an avoidance of doing something, occurs when a child has the skill but chooses not to use it because the task is too difficult, boring or unappealing. In this case, the cost of the effort outweighs the value of the reward for the child.

Comparison Area	Can’t	Won’t
Core Meaning	The child does not yet have the prerequisite skills, motor planning, sensory tolerance, or processing ability needed to complete the task.	The child has the skill but avoids using it because the task feels too hard, boring, unpleasant, or not worth the effort.
What It May Look Like	The child cries, freezes, struggles physically, makes repeated errors, or becomes distressed even with support.	The child ignores the instruction, walks away, delays, negotiates, or resists when asked to do the task.
Main Cause	A skill deficit or sensory barrier is getting in the way.	A performance deficit is present, meaning motivation and task conditions are the issue.
How ABA Helps Identify It	The child still cannot complete the task even when support and strong reinforcement are provided.	The skill appears when motivation increases, the setting changes, or the child is offered a meaningful incentive.
Best Response	Teach the missing skill, reduce barriers, and provide structured support.	Adjust motivation, build momentum, and make the task feel more manageable and worthwhile.

How ABA Professionals Solve the Mystery

Board Certified Behavior Analysts (BCBAs) use a scientific approach called Functional Behavior Assessment (FBA) to determine which category a behavior falls into

Here are the primary methods used to tell the difference.

The Big Motivation Test

One of the simplest ways to check for ability is to increase the reinforcement. If a child can’t put on their shoes, we might offer a very high-value incentive to see if the skill emerges.

If the child suddenly puts the shoes on perfectly, we know we are dealing with a performance deficit (avoidance). If they still struggle and become distressed despite the reward, we are likely looking at a skill deficit (inability).

Generalization Checks

We look at the child’s history to see if the child has performed this skill before.

If a child could zip their coat yesterday but can’t today, it is unlikely they lost that physical ability overnight. It may be that they are tired, the environment is too loud or they are simply avoiding the transition to going outside.

Sensory and Environmental Scan

Sometimes, an inability is actually a sensory barrier. A child might have the fine motor skills to wash their hands, but the sensory inability to tolerate the water temperature or the scent of the soap makes the task feel impossible.

In these cases, the avoidance is a self-protective measure against sensory overload.

Situation	Recommended ABA Strategies	How the Strategy Helps
When a child truly can’t do the task	Errorless learning, task analysis, prompting hierarchies	These methods reduce failure, break larger goals into small steps, and help the child build confidence and competence over time.
When a child can do the task but avoids it	Behavioral momentum, Premack Principle (First/Then), choice-making	These strategies increase motivation, reduce resistance, and help the child engage with less stress.
When the difference is unclear	Functional Behavior Assessment, reinforcement testing, generalization checks, sensory and environmental review	These tools help identify whether the barrier is skill-based, motivation-based, sensory-based, or influenced by the environment.
When parents notice patterns at home	Documenting what happens, when it happens, and under what conditions	Parent observations give the clinical team real-world context and help personalize the treatment plan.

Strategies for Supporting Inability

When a child truly can’t perform a task, pushing for compliance is counterproductive. Instead, ABA therapists focus on skill acquisition, through strategies such as …

Errorless Learning: We provide immediate prompts so the child can’t fail, gradually fading those prompts as the child gains confidence and muscle memory.
Task Analysis: We break a large goal (such as brushing teeth) into tiny, achievable steps (picking up the brush, wetting the bristles, etc.).
Prompting Hierarchies: We move from physical guidance to visual cues, ensuring the child feels supported at every stage.

Strategies for Overcoming Avoidance

If the child has the skill but is avoiding the work, we shift our focus to Motivation and Behavioral Momentum, using strategies such as …

Behavioral Momentum: We ask the child to do three easy things they love before asking for the hard thing they are avoiding. This builds a “yes” habit.
Premack Principle (First/Then): We clearly communicate that the hard task is a gateway to a preferred activity. For example, “first put away two blocks, then we go to the swing.”
Choice-Making: Giving a child a sense of agency can reduce avoidance. For example, “do you want to use the blue crayon or the red crayon for your homework?”

The Role of Parent Observation

Parents see the real-world version of these behaviors every day. You might notice that your child has no trouble opening a bag of chips but can’t seem to figure out how to open their lunchbox.

These observations are gold mines for your BCBA. By documenting when and where these struggles occur, you help the clinical team tailor the treatment plan to your child’s specific needs.

Blue Gems ABA Bridges the Gap for Children with ASD

At Blue Gems ABA, we don’t believe in generic labels. We know that a child’s ability can fluctuate based on their health, their sleep and their environment.

Our therapists are trained to look past the surface behavior to understand the underlying cause. Whether your child needs to learn a new skill or the right motivation to use the skills they already have, we are here to support them.

To learn more about how we assess and support your child’s unique learning journey, please contact us today.

FAQs

How can parents tell whether a child can’t or won’t do a task?

Parents can look for patterns. If the child shows the skill in other settings or with stronger motivation, the issue may be avoidance. If the child consistently struggles even with support, the issue may be inability.

Why is this distinction so important in ABA therapy?

Because the intervention changes based on the cause. A skill deficit calls for teaching and support, while avoidance calls for strategies that improve motivation, task structure, and engagement.

Can sensory issues make a child seem unwilling when they actually can’t participate?

Yes. A child may have the physical skill to complete a task but still feel unable to do it because the sensory experience is overwhelming or distressing.

What does ABA do when a child truly can’t complete a task yet?

ABA therapists focus on skill-building through structured methods such as task analysis, prompting, and errorless learning so the child can succeed step by step.

How can parents help the therapy team?

Parents can share observations about when the behavior happens, what the environment is like, and whether the child shows the skill in other moments. That information helps shape a more personalized plan.