Assent vs Consent in ABA: What's the Real Difference?

Consent is the caregiver's legal yes signed once at the start of services. Assent is the kid's ongoing yes, measured all session long. Picture a strep test at the doctor's office. The parent signed the consent form in the waiting room. But the moment that swab gets close to the back of the throat, the kid either keeps their mouth open or turns their head away. The signature is consent. The open mouth is assent. ABA needs both.

The one-sentence difference#

Consent is one signed yes that covers a whole intervention. Assent is the learner's moment-by-moment yes that can change at any second. A signed form does not make a session okay. A kid's body language during minute thirty-seven does.

This matters because the two words sound alike and get mixed up constantly. They are not the same thing. They do not protect the same person. They do not get gathered the same way. And in ABA, you almost always need both at once.

"Consent with a C is singular. It is one instance following understanding that indicates continuous acceptance of the intervention that was agreed to." From the talk — Matt Harrington

Consent: one signature at the doctor's office#

Consent is a legal yes. It happens once, before the intervention starts. The person giving consent has to be old enough and able enough to understand what they are agreeing to. They hear the plan. They hear the risks. They hear the benefits. Then they sign.

For most kids in ABA, the parent or legal guardian signs. The kid is too young or has a disability that means the law does not let them sign for themselves. So consent is the parent's job.

Once that signature is on the paper, the clinical team has legal permission to run the intervention for the time period the paperwork covers. That is it. Consent does not get re-asked every session. It does not get re-asked every trial. It is one yes that holds until the paperwork expires or somebody pulls it back in writing.

"Many of the clients we work with would not be legally able or allowed to give consent." From the talk — Matt Harrington

That is the legal frame. Now here is where ABA gets different.

Assent: the strep test in real time#

Assent is what the kid is telling you with their body and their behavior, right now, in this moment. It is not a signature. It is a stream of small yeses and small nos that you have to watch for the whole time you are working.

Go back to the strep test. Mom signed the consent form. But the kid is the one with the throat. If the kid opens their mouth and lets the swab in, that is assent. If the kid turns their head away, pushes the stick back, or slaps the swab out of the nurse's hand after, that is assent withdrawal. The signature did not change. The kid's behavior did.

"If they're looking for ascent with an A for that same shrep test, well, that would be measured by me not turning away my head when the little stick is coming through." From the talk — Matt Harrington

In a clinic, assent looks like a kid sitting at the table and working through a discrete trial. Discrete trials, often called DTT, are short structured teaching moments where the BCBA (the Board Certified Behavior Analyst, the clinician who writes the plan) or the RBT (the Registered Behavior Technician, the person running the sessions) presents a task and reinforces a correct response. Assent withdrawal looks like the kid pushing the cards away, leaving the chair, covering their ears, or quietly going silent and not responding.

The key word is ongoing. You do not get assent once and keep it forever. You earn it every minute.

Why ABA leans harder on assent than SLP or OT#

Speech-language pathologists (SLPs) and occupational therapists (OTs) work with the same kinds of kids ABA does. They also care about how the kid is feeling during the session. But ABA sessions are usually much longer, and that changes everything.

A speech session might run thirty minutes. A pediatric OT block might run forty-five. An ABA session often runs three, four, six, even eight hours. That is a whole school day of one-on-one work. The kid you started with at 8 a.m. is not the same kid at 3 p.m. Hunger, tiredness, and stress add up.

"Our session lakes tend to be significantly longer than our counterparts, mental health therapists, SLPs, OTs. A five-year-old saying yeah, let's get started with therapy at 8am is not the same five-year-old who says yeah, let's do the ninth DTT task at 3.30pm with no nap." From the talk — Matt Harrington

Because the session is long, the BCBA cannot just check in once at the start. The team has to read assent over and over. That is why ABA leans on assent in a way the shorter therapies usually do not have to.

When you need both (and when consent alone is fine)#

You need both consent and assent for every ABA session. Consent gives you legal permission to be in the room. Assent tells you whether the kid is actually okay with what is happening today, right now, on this task.

A simple way to think about it:

• No consent, no session. You cannot start. The paperwork has to be in place.
• Consent but no assent, change something. The legal yes is there, but the kid is telling you with their body to stop. Back off. Then change the task, the setting, or the reinforcement before you try again.
• Consent and assent, keep going. Both yeses are present. Run the trial.

There are short moments outside ABA where consent alone really is fine. A blood draw the kid agreed to at the start but cried through. A vaccine the parent signed off on. The doctor finishes the job because the medical need is high and the moment is short. ABA almost never has that excuse. The sessions are too long, the tasks are too repeatable, and the goals are about long-term skills, not a thirty-second medical procedure. If the kid is pulling assent, the team has time to stop and rework the plan. That is the standard.

The audit angle#

This is where the comparison page becomes a tool you can actually use. When a BIP (behavior intervention plan, the written plan the BCBA writes to guide each session) gets reviewed by a supervisor, an insurance auditor, or a parent, the question is no longer "did you have consent." The question is "can you show me both."

Consent shows up as a signed form in the chart. Easy.

Assent has to show up in your data. That means the BIP should name the small behaviors that count as assent withdrawal for this specific kid. Not just hitting or screaming, but the quiet stuff too: looking away, going silent, sliding off the chair, covering ears. Then the data sheet should track when those happened and what the RBT did next.

If the chart shows assent withdrawal six times in a row with no change to the task, that is a problem. If the chart shows assent withdrawal twice, then a task change, then a re-presentation, that is assent-based care on paper. Same kid, same goal, very different audit story.

Quick reference table for your treatment plan#

Frequently asked questions#

Can a parent give assent on behalf of their child?

No. A parent gives consent. Assent has to come from the kid because assent is about what the kid is doing in the moment. The parent is not in the chair during the DTT trial. The kid is. The closest a parent can get is helping the team understand their kid's signals, like what quiet withdrawal looks like for this child, so the RBT can spot it earlier.

If I have consent, do I still need assent?

Yes. Consent gets you legally cleared to run the plan. Assent tells you whether to keep running it right now. A signed form does not make a hard session okay. If the kid is showing assent withdrawal and the team keeps pushing the same task without changing anything, that is a problem even when the consent paperwork is perfect.

Is verbal "yes" enough to count as assent?

Not by itself. A kid can say "yes" and still be pulling away with the rest of their body. Real assent is the whole picture: words, body, engagement with the task, and what happens after the trial ends. Two yeses in a row from a tired kid who is also turning their head and dropping the cards is not assent. It is compliance under pressure. The team has to read the whole signal.

Keep learning#

Consent and assent are the floor, not the ceiling. Once you can tell the two apart on paper, the next step is making your sessions actually run on assent: knowing what withdrawal looks like for your kid, what to do the second you see it, and how to build skills that make the hard moments easier over time.