“But They Can Do It When They Want To”: Understanding Inconsistent Performance
Child-focused mental health professionals frequently hear, “But I know they can do it. I’ve seen them do it before.” When a child’s performance varies across situations, it can be tempting to interpret that inconsistency as a matter of motivation. But being able to perform a skill sometimes does not necessarily mean a child can reliably access it when needed.
Inconsistent performance, however, does not necessarily mean inconsistent willingness. A child’s ability to access a skill can vary considerably depending on the setting, demands, emotional state, and supports available.
The more clinically useful question is not simply “Can this child do it?” but rather:
“What is different about the situations in which this child succeeds versus the situations in which they struggle?”
Capacity Is Not the Same as Consistent Performance
Knowing how to perform a skill and being able to reliably perform that skill when needed are not necessarily the same thing. A student may demonstrate that they understand a math concept but struggle to initiate a worksheet independently. A child may know how to use a coping strategy but be unable to access it when highly distressed.
Performance is influenced by much more than knowledge or skill. Sleep, hunger, stress, cognitive load, environmental distractions, task difficulty, emotional arousal, novelty, and competing demands can all affect whether a child is able to use a skill in a particular moment.
This is why “They did it yesterday” does not necessarily mean “They can do it today.” Previous success is important information, but it does not tell us that all of the conditions supporting that success are present every time.
Executive Functioning Can Make Performance Look Especially Inconsistent
Executive functioning difficulties can be particularly confusing for adults. Consider a student with ADHD who spends an hour intensely focused on a preferred activity but appears completely unable to begin a relatively simple assignment. From an outside perspective, this can look like a choice: “If they can focus on that, they can focus on this.”
However, interest, novelty, urgency, immediate feedback, and external structure can substantially affect executive functioning and task engagement. The issue may not be whether the student possesses the underlying skill, but whether the conditions are supporting them in accessing it.
Similarly, a child may complete a multistep routine independently when an adult has established predictable cues but struggle when expected to organize the same routine without those supports. Rather than viewing this as evidence that the child is choosing not to comply, clinicians can ask which component of the task is breaking down.
Anxiety Can Look Inconsistent, Too
Anxiety-related difficulties are also highly context-dependent. A child might give a presentation one week and refuse to present the next. They may enter school independently on Tuesday but struggle at the door on Wednesday. A child with social anxiety or selective mutism may speak comfortably with one person while becoming unable to speak with another.
These differences do not necessarily indicate manipulation or that the child is “choosing” when to be anxious. Instead, they provide valuable information about the variables influencing the behavior.
What changed? Was the audience larger? Was the child already overwhelmed? Was the task more difficult? Was a particular person present? Had there been a stressful event earlier that day?
The inconsistency itself can become part of the assessment.
Motivation Matters—But It Is Not the Same as “They Just Don’t Want To”
It is important not to swing too far in the opposite direction. Motivation does matter. Children, like adults, are more likely to engage in behaviors that are interesting, rewarding, achievable, or immediately meaningful. Reinforcement influences behavior, and avoidance can become reinforced when it consistently allows a child to escape something difficult.
But recognizing the role of motivation does not mean reducing behavior to “they just don't want to.” A child may simultaneously have a genuine skill deficit, difficulty tolerating frustration, and a history of learning that avoidance makes uncomfortable situations go away.
The goal is not to determine whether a child “can” or “won’t.” Often, the answer involves some combination of skill, motivation, reinforcement, environment, and emotional state.
From Judgment to Functional Assessment
When adults say, “But I know they can do it,” clinicians can use that statement as a starting point for functional assessment rather than as evidence that the child is refusing.
Ask: Under what conditions can they do it?
Compare situations in which performance is stronger with situations in which it deteriorates. For example, a child may perform better with one-to-one adult support, interesting or novel tasks, short and clear directions, immediate reinforcement, predictable routines, or lower emotional arousal. Performance may worsen during independent work, repetitive tasks, multistep directions, transitions, delayed reinforcement, or periods of anxiety and frustration.
These comparisons can point directly toward intervention.
A Practical Framework for Clinicians
When you hear “But I know they can do it,” consider the following:
Define the behavior. What specifically is not happening? Avoid vague descriptions such as “won’t cooperate” or “is unmotivated.”
Identify when it does happen. What is different about the situations in which the child succeeds?
Examine antecedents. What happens immediately before the difficulty? Consider task demands, transitions, people present, instructions, and emotional state.
Examine consequences. What happens after the behavior? Does the child escape a demand, receive additional support or attention, or gain access to something more preferable?
Assess the demands involved. Does the task require executive functioning, frustration tolerance, academic skills, social communication, or anxiety management?
Adjust support without eliminating expectations. Scaffold the specific point of difficulty, reinforce successful engagement, and gradually fade support as the child becomes more independent.
The goal is not to lower expectations simply because performance is inconsistent. Rather, it is to understand what makes success more accessible and then intentionally build those conditions into intervention.
A child’s best performance tells us something important: the skill may be accessible under at least some conditions. Our job is to understand those conditions, identify the barriers that interfere with performance elsewhere, and help the child gradually develop greater flexibility and independence.
Instead of asking, “Why won't they do it when I know they can?” we can ask a more useful question:
“What does this child need in order to access what they already know how to do—and how can we help them need that support less over time?”