"Presume competence" is one of the most important ideas in AAC. It's also one of the most misunderstood.
Some people hear it as blind optimism. Others interpret it as ignoring real challenges. Neither is accurate. Presuming competence is a decision-making framework with practical consequences for how we provide AAC services, set goals, and include people in their own lives.
Let's look at where the idea came from, what it actually means, and why it matters for anyone who uses or supports AAC.
The Origin: Donnellan's Least Dangerous Assumption
The concept traces back to Anne Donnellan's 1984 paper, "The Criterion of the Least Dangerous Assumption." Donnellan, a special education researcher, posed a straightforward question: when we don't know what someone is capable of, which assumption is safer to act on?
She laid out two options:
Option A: Assume the person is competent, provide full access to communication and education, and be wrong. Result: you gave someone opportunities they didn't fully benefit from, but they were included and respected.
Option B: Assume the person is not competent, restrict access to communication and education, and be wrong. Result: you denied a capable person the chance to learn, communicate, and participate in life.
Donnellan's argument was that Option A is clearly less dangerous. If you're going to be wrong, be wrong in the direction that does less harm.
This wasn't about ignoring someone's disability or pretending challenges don't exist. It was about recognizing that our assessments of ability are imperfect, and when they're imperfect, we should err on the side that protects the individual's rights.
What Presuming Competence Looks Like in Practice
Presuming competence is not a feeling. It's a set of actions. Here's what it looks like when applied to AAC:
Providing robust vocabulary from the start
A competence-presuming approach gives the AAC user access to a full vocabulary system from the beginning. This means core words, fringe vocabulary, alphabet access, and the ability to say anything, not just make requests.
The alternative, giving someone a device with only 8 pictures of snacks and toys, presumes they have nothing to say beyond basic wants. That assumption limits what they can express and, over time, limits what they learn to express.
Setting ambitious goals
If we presume competence, our therapy goals reflect it. Instead of "the child will request 5 preferred items," a competence-presuming goal might be "the child will combine two or more symbols to comment, ask questions, and make requests across three settings."
The first goal assumes the child is a requester. The second assumes they are a communicator.
Teaching literacy
Presuming competence means providing literacy instruction alongside AAC. Not assuming that someone can't learn to read because they don't speak. Not waiting until they "prove they're ready." Research from Erickson and Koppenhaver (2020) has shown that individuals with complex communication needs can develop literacy skills when given systematic instruction, even when traditional readiness indicators are absent.
Including people in decisions about their own communication
This means asking AAC users what vocabulary they want. Letting them choose their device layout. Involving them in IEP meetings and goal-setting, even if that participation looks different from what we expect. It means treating them as the primary stakeholder in their own communication system.
Offering age-appropriate content
A 15-year-old who uses AAC should have access to the same topics, books, and social vocabulary as their speaking peers. Presuming competence means not infantilizing someone because of their communication method. For families navigating this stage, our guide on AAC for teenagers addresses the specific challenges of starting or continuing AAC in adolescence, including social dynamics and building independence.
How Low Expectations Limit AAC Access
The consequences of not presuming competence are well-documented. Research has consistently shown that expectations shape outcomes for people with disabilities.
The expectation gap
Research consistently finds that people who use AAC receive lower expectations than speaking peers with similar cognitive profiles. These lower expectations translate into less instructional time, simpler curriculum, and fewer opportunities for social interaction.
This creates a cycle. Lower expectations lead to fewer opportunities. Fewer opportunities lead to slower progress. Slower progress is then used as evidence that the low expectations were justified. The person's potential is never tested because the environment never demands it.
Gatekeeping through "readiness"
One of the most damaging consequences of not presuming competence is the concept of "readiness" for AAC. Historically, individuals were required to demonstrate certain prerequisite skills before receiving an AAC system. These prerequisites included things like cause-and-effect understanding, symbolic play, or the ability to match pictures.
The problem, as documented by Kangas and Lloyd (1988) and reiterated in ASHA's current position statements, is that there is no evidence these skills are necessary before someone can benefit from AAC. Many individuals develop these skills through AAC use rather than before it.
The self-fulfilling prophecy
Jorgensen, McSheehan, and Sonnenmeier (2010) described how presumptions about competence become self-fulfilling prophecies in educational settings. When teachers presumed a student with complex communication needs was competent, they provided grade-level instruction, expected participation, and created opportunities for learning. When they didn't, they provided simplified activities with minimal communication demands.
Students in the first group made more progress. Not because they started with more ability, but because they were given more opportunity.
Research on Expectation Effects
The relationship between expectations and outcomes is not unique to AAC. It's one of the most consistent findings in educational and psychological research.
Rosenthal and Jacobson (1968)
The classic "Pygmalion in the Classroom" study showed that when teachers were told (falsely) that certain students were "intellectual bloomers," those students showed significantly greater IQ gains than control students. The teachers' expectations changed their behavior, which changed the students' outcomes.
Jussim and Harber (2005)
A comprehensive review of expectation effects in education found that teacher expectations do influence student achievement, though the effects are generally more moderate than earlier research suggested. Importantly, they found that expectation effects tend to be larger for students from stigmatized groups, which includes students with disabilities.
The connection to self-determination
Research on self-determination for people with significant disabilities shows that self-determination skills are strong predictors of positive adult outcomes. Wehmeyer and Palmer (2003) found that students with higher self-determination were more likely to live independently and be employed after high school. When staff presume competence and provide opportunities for choice-making and self-advocacy, they help build the self-determination skills that lead to better outcomes.
Practical Ways to Presume Competence Daily
Presuming competence is not a one-time declaration. It's something you practice in small decisions every day. Here are concrete ways to do it:
Talk to the person, not about them
When a child who uses AAC is in the room, direct your comments and questions to them. Not to their parent, teacher, or aide. Even if you're not sure they understand everything, speaking to them directly communicates respect and inclusion.
Wait longer for responses
AAC takes time. Forming a message on a device is slower than speaking. Giving someone 10 to 20 seconds to respond (instead of the 3 seconds we typically wait in conversation) presumes they have something to say and are working on saying it.
Assume understanding until proven otherwise
If you're explaining something to a class and a student who uses AAC is present, assume they're following along. Use the same vocabulary and concepts you use with everyone else. Simplify only if there's specific evidence that the content is inaccessible, not simply because the person doesn't speak.
Provide a comprehensive AAC system
Giving someone a device with 50 words presumes they only have 50 things to say. A full AAC system with thousands of words and alphabet access presumes they might want to say anything. Choose the second option.
Respond to all communication attempts
Vocalizations, gestures, reaching, eye gaze, facial expressions. These are all communication. Responding to them validates the person's communicative intent and builds motivation to communicate more.
Stop requiring proof
Don't make someone "prove" they can use a simple system before giving them a complex one. Don't require a cognitive assessment before providing AAC. Don't wait for them to master single words before introducing multi-word combinations. Provide access first. Assess what they can do with that access.
What Presuming Competence Is Not
To avoid misunderstanding, let's be clear about what this concept does not mean:
It does not mean ignoring disabilities. Presuming competence doesn't mean pretending someone doesn't have challenges. It means providing support for those challenges while maintaining high expectations.
It does not mean withholding support. A competence-presuming approach provides more support, not less. It means offering a full AAC system with training, modeling, and ongoing customization.
It does not mean all outcomes will be the same. Different people will achieve different things. Presuming competence means giving everyone the opportunity to show what they can do, not predicting that everyone will do the same thing.
It does not mean ignoring assessment data. Assessment is important. But assessment should guide how we support someone, not whether we support them.
The Bottom Line
Presuming competence is not optimism. It's risk management. When we don't know someone's potential, and we never fully do, we choose the assumption that protects their rights and maximizes their opportunities.
For AAC, this means providing comprehensive communication systems, setting ambitious goals, teaching literacy, and treating every communicator as someone with something to say.
The alternative, underestimating someone and limiting their access to communication, is a risk we should never be willing to take.
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References
- Donnellan, A.M. (1984). The criterion of the least dangerous assumption. Behavioral Disorders, 9(2), 141-150.
- Erickson, K.A., & Koppenhaver, D.A. (2020). Comprehensive Literacy for All: Teaching Students with Significant Disabilities to Read and Write. Paul H. Brookes Publishing.
- Kangas, K.A., & Lloyd, L.L. (1988). Early cognitive skills as prerequisites to augmentative and alternative communication use: What are we waiting for? Augmentative and Alternative Communication, 4(4), 211-221.
- Wehmeyer, M.L., & Palmer, S.B. (2003). Adult outcomes for students with cognitive disabilities three-years after high school: The impact of self-determination. Education and Training in Developmental Disabilities, 38(2), 131-144.
- Jorgensen, C.M., McSheehan, M., & Sonnenmeier, R.M. (2010). The Beyond Access Model: Promoting Membership, Participation, and Learning for Students with Disabilities in the General Education Classroom. Paul H. Brookes Publishing.
- Rosenthal, R., & Jacobson, L. (1968). Pygmalion in the Classroom: Teacher Expectation and Pupils' Intellectual Development. Holt, Rinehart & Winston.
- Jussim, L., & Harber, K.D. (2005). Teacher expectations and self-fulfilling prophecies: Knowns and unknowns, resolved and unresolved controversies. Personality and Social Psychology Review, 9(2), 131-155.