
05/07/2025
Who’s up to nerd out on function?
A functional behaviour assessment (FBA), especially when we’re addressing what gets labelled as a “problem behaviour,” gives us a foundation to work from. A good FBA is a working hypothesis, not a final answer. It helps us make an informed guess about what the behaviour is doing for the learner and what consequence is reinforcing it. That function isn’t necessarily fixed. It can shift depending on context, experience, or competing motivations.
Of course, not all behaviour is purely operant. Reflexes, emotional responses, and conditioned associations all play a role. But when we're trying to change or maintain behaviour in applied settings, understanding function gives us an essential entry point.
Once we understand the function, we can often teach a different behaviour that achieves the same goal for the individual.
Let’s say I’m trying to work. I’m mid-sentence or editing a paper, and my partner keeps interrupting me with questions or small talk. Eventually, I snap: “Can you not right now?” It’s not ideal, but it works. He backs off. I get the space I need. That snapping gets reinforced because it reliably leads to escape from interruption and a return to focus.
Now, what if instead I learn to say, “Give me 30 uninterrupted minutes, and I’ll check in after”? And what if that works, and I get the quiet I was asking for? That new behaviour still meets the same need: relief from disruption. It’s a lot nicer for him and a lot less frustrating for me.
That’s the core of this. We’re not just reinforcing a new behaviour. We’re making sure it actually serves the same purpose as the original one.
Sometimes we can’t match the original reinforcer exactly, but we can look for ways to come close or compete with it.
Still, it’s not just about delivering something reinforcing. Even if a new behaviour is technically reinforced, it may not hold across contexts unless the reinforcement actually meets the same need.
Take a dog who barks and lunges at other dogs. If I teach them to turn and look at me instead, and I reward that with a treat, but what they really needed was distance (and that’s not happening reliably), that behaviour may fall apart the moment the food disappears. Or it may never really stick if food wasn’t the relevant reinforcer to begin with.
That doesn’t mean treats are useless. Far from it. Food can be an excellent reinforcer and can help us build emotional safety into the process. It can build reinforcement value and strengthen new behaviours quickly and clearly. But if the original behaviour was functioning to prevent an interaction or create space, then the replacement behaviour should also result in space. The treat can enhance the learning process, but it doesn’t necessarily replace the reinforcer that actually satisfies the need.
Timing matters, too. If the dog turns to look at me but I don’t notice or I hesitate before responding, then the replacement behaviour isn’t getting reinforced under the right conditions.
The same is true for people. If I ask for uninterrupted time and my partner doesn’t follow through, the polite behaviour loses its value. This is where stimulus control comes into play. The cue to perform the new behaviour needs to be clear, and the consequence needs to follow consistently enough that the behaviour becomes reliable.
It’s also worth noting that some behaviours are emotionally charged. Snapping at a partner or barking at a dog may come with a surge of frustration, fear, or urgency. That doesn’t mean the behaviour isn’t functional, but it does mean we may need to support the learner in regulating arousal as part of the process, especially when we’re replacing high-intensity responses with more subtle or lower-effort alternatives.
The same principle applies to maintenance. If I ask my partner to give me 30 minutes, but he keeps interrupting anyway, I’ll probably snap again. Not because I’m being unreasonable, but because the polite request didn’t work. The original behaviour still does. (Sorry, Mike. I hope I don’t do that too often.)
Take Juno, for a slightly different example.
She’s generally uncomfortable around unfamiliar dogs who run up to say hello uninvited. Her default used to be a sharp, knee-jerk “telling off.” Sometimes it worked and the other dog would back off. Sometimes it didn’t. But the function was clear: she wanted space.
Over time, I helped her learn that she could say no in more subtle ways, and often before the dog even reached her. A stop. A head turn. A lip lick. A paw lift and hold. Avoiding eye contact. Sometimes just trotting off in another direction, depending on the approaching dog and how they were communicating. These are all natural and normal cut-off signals. These behaviours still communicated her boundary, but with far less mental and physical effort. And importantly, they still worked. In fact, they often worked better than the original outburst.
But here’s the thing. Sometimes, they don’t. Some dogs don’t take the hint. They ignore her signals. They pester. And in those moments, when her more subtle requests are ineffective, she sometimes escalates to shouting. The behaviour that was supposed to meet her need didn’t deliver.
This is why matching the function of reinforcement matters more than just offering something pleasant or preferred. A different reinforcer might work under some conditions, but not others. And if we want the new behaviour to last, especially when things get stressful or when reinforcement becomes intermittent, we have to make sure the need the original behaviour was meeting is still being met.
Depending on the situation, we can also reduce the value of that original reinforcer by offering it in other, more predictable ways. If I know I’ll get regular blocks of uninterrupted focus time during my day, and I trust that those boundaries will be respected, I’m much less likely to snap when my partner talks to me while I’m working. The behaviour loses its urgency because the need is already being met in other ways.
That’s the real work: identifying the function, matching it in our teaching, and reinforcing behaviours that truly serve the learner.