Why “He Knows It but Doesn’t Do It” Can Be More Complex Than It Sounds
“He knows how to do it. He just doesn’t do it.”
It is a phrase many parents hear when a child can demonstrate a skill in one situation but struggles to use it independently in everyday life.
A child may follow a direction during therapy but not at home. They may know how to request something but become frustrated instead of communicating when they really want it. They may demonstrate a social skill with a therapist but find it difficult to use the same skill with siblings, teachers, or peers.
This does not necessarily mean the child is refusing, being lazy, or choosing not to cooperate. Knowing a skill and being able to use that skill consistently, independently, and in different situations are not always the same thing.
Knowing a Skill Is Only One Part of Learning
Learning is more than being able to perform a task under one set of conditions.
For a skill to become functional, a child may need to learn when to use it, where to use it, with whom to use it, and how to use it without constant prompting.
This is particularly important when supporting children with developmental differences, including autism. The American Academy of Pediatrics identifies functional communication, social skills, adaptive skills, and independence as important areas of intervention. It also emphasizes the importance of helping children apply learned skills across different environments.
For example, a child might successfully complete a hand-washing routine when a therapist gives step-by-step prompts. That demonstrates that the child can perform the routine with support. However, the longer-term goal may be for the child to recognize when hand washing is needed, initiate the routine, complete the steps, and do so at home, school, or in the community.
That process takes teaching beyond simply “knowing.”
Why Doesn't the Skill Always Show Up?
There can be several reasons.
1. The Skill May Not Be Fully Independent
Sometimes a child appears to know a skill because they have learned to respond to prompts.
For example, if an adult repeatedly says, “Tell me what you want,” before a child requests an item, the child may learn to respond after that prompt. But if the adult is not there to provide the cue, the child may not initiate communication independently.
A Behavior Therapist or Behavior Analyst can assess how much support a child needs and gradually work toward greater independence by systematically reducing prompts.
2. The Child May Not Have Generalized the Skill
Generalization means using a learned skill in different situations, with different people, materials, or environments.
A child might learn to greet a therapist in a therapy room but not greet a teacher at school. This does not necessarily mean the child has forgotten the skill. The skill may simply not yet be generalized.
Research examining social-communication interventions in autistic children has found that generalization can occur across people, settings, and activities, although it is not always consistent across every skill. This highlights why generalization needs to be deliberately considered during intervention rather than assumed to happen automatically.
3. Communication and Behavior May Be Connected
Sometimes what looks like “not following instructions” may actually reflect a communication difficulty.
A child who cannot easily communicate “I don't understand,” “I need help,” “I don't want this,” or “I need more time” may communicate through behavior instead.
The American Academy of Pediatrics notes that strengthening communication and social skills can help address concerning behaviors, and that functional communication should be an important part of support for children with autism.
This is where Autism Behavior Therapy and communication-focused intervention can complement one another. Rather than simply trying to stop a behavior, professionals can look at what the child is communicating and teach a more functional way to express that need.
Speech Is Not the Only Measure of Communication
Another common misconception is that communication means speaking in sentences.
Communication can include spoken language, gestures, signs, pictures, communication boards, or speech-generating devices. The appropriate approach depends on the individual child's abilities and needs.
The American Academy of Pediatrics recognizes augmentative and alternative communication (AAC) as one option that can support communication for children who have difficulty communicating through speech.
A Speech Therapy program may therefore focus on much more than vocabulary. Depending on the child's needs, goals can include requesting, responding, understanding language, initiating interaction, taking turns, using language socially, and communicating needs more effectively.
What Can Professionals Do?
The first step is to understand why the skill is not occurring consistently.
Professionals may look at:
What the child can already do independently
What prompts or assistance are required
Where the skill occurs successfully
Where it breaks down
What happens immediately before and after the behavior
Whether the child understands the instruction
Whether communication difficulties are contributing
Whether the skill has been practiced across people and environments
Intervention can then be individualized around the child's actual needs.
Evidence-based behavioral approaches can be used to teach specific skills systematically, while speech and language professionals can address communication needs. The American Academy of Pediatrics recommends individualized,