AAC Abandonment and Motor-Planning Consistency
Why 50-90 % of AAC devices are abandoned within the first year — and the three predictable causes that account for most cases.
By Davit Janunts, M.Ed. Special Education (Lehigh University — Fulbright Foreign Student Program); co-author, Morin, Janunts, et al. (2024), Exceptional Children, 90(2), 145-163, doi:10.1177/00144029231165506.
Summary
The 50-90 % AAC abandonment rate documented by Johnson, Inglebret, Jones & Ray (2006, Augmentative and Alternative Communication, 22(2), 85-99) is the most-cited figure in the AAC field — and the most often misread. It is not a measure of student capacity. It is a measure of the system around the student: the device’s vocabulary organization, the consistency of motor-planning locations across reprogramming events, and the dose of communication-partner instruction the family and the school team received. The systematic-review update by Moorcroft, Scarinci & Meyer (2019, Disability and Rehabilitation: Assistive Technology, 14(7), 710-731) replicates the abandonment finding and decomposes it into three categories of cause that districts can audit at the IEP-team level. This brief sets out those three categories and the field-level signals that distinguish a sustained AAC implementation from one that is in the process of failing.
The cost shape — what abandonment actually means
For a non-speaking or minimally-speaking student, the AAC device is the channel through which they speak. United Nations Convention on the Rights of Persons with Disabilities (2006), Article 21, frames access to communication — including AAC — as a human right. Romski & Sevcik (2005, Infants & Young Children, 18(3), 174-185) and Millar, Light & Schlosser (2006, Journal of Speech, Language, and Hearing Research, 49(2), 248-264) document that AAC supports — not inhibits — natural speech: 89 % of users in the Millar et al. case series showed speech-production gains; 0 % showed decreases. Abandonment therefore costs the student not only the AAC channel but also the speech gains that channel was scaffolding.
The financial cost is real but secondary. The clinical and legal cost is the failure to deliver an IEP-documented related service: when AAC is named in the IEP and the student is not actually using it, the district has not delivered FAPE on that goal. Kent-Walsh, Murza, Malani & Binger (2015, Augmentative and Alternative Communication, 31(4), 271-284) report a meta-analytic effect of d=1.34 for communication-partner instruction on AAC user output — meaning the largest single intervention in the AAC literature is training the adults around the student, and that intervention is the one most often skipped at the district level.
Three predictable causes that account for most abandonment
1. Motor-plan disruption — vocabulary moving locations
AAC use is a motor task. A user who has learned that “more” is at a fixed grid position has built a motor plan to that position. Reprogramming the device — changing the vocabulary system, rearranging the grid, switching between symbol sets — destroys that motor plan. Thistle & Wilkinson (2015, AAC, 31(2), 124-136) and the Light, Wilkinson, Thiessen et al. (2019, AAC, 35(1), 42-55) state-of-the-science review establish that consistent symbol-location placement is one of the most consistent design predictors of sustained AAC use across developmental and acquired disabilities. The structural compliance signal here is operational, not diagnostic: has the student’s core vocabulary moved position in the last six months? If yes, the abandonment risk is high regardless of any other factor. The Language Acquisition through Motor Planning (LAMP) framework operationalizes this principle by treating each word’s grid position as a fixed motor target.
2. Inadequate communication-partner instruction
Kent-Walsh, Murza, Malani & Binger (2015) is the largest peer-reviewed meta-analysis on AAC intervention modality: communication-partner instruction (training the family member, teacher, paraprofessional, or peer who interacts with the AAC user) produces an effect size of d=1.34 on the AAC user’s communicative output. Sennott, Light & McNaughton (2016, RPSD, 41(2), 101-115) extend this with explicit AAC modeling — partners who model AAC use during natural interaction produce gains across pragmatics, semantics, syntax, and morphology in participating children. The structural signal is documentable: has every adult in the student’s communication environment received explicit AAC partner instruction in the last twelve months? When the answer is no, abandonment within the year is the modal outcome.
3. Vocabulary mismatch — fringe-heavy displays without core
Banajee, Dicarlo & Stricklin (2003, AAC, 19(2), 67-73) established that approximately 80 % of toddlers’ everyday utterances are built from a small core vocabulary — fewer than 400 words — that recurs across topics. Devices configured primarily with topic-specific fringe vocabulary (the foods on the menu, the names of family members, the toys in the room) without an organized core-vocabulary layout fail at general communication even when they succeed at single-context labeling. Light & McNaughton (2014, AAC, 30(1), 1-18) frame this in their four-domain communicative-competence model: linguistic competence requires access to the productive grammatical system, which fringe-only displays do not provide. The structural signal: does the student’s display include an organized core-vocabulary section accessible from the home screen, with every core word at a fixed motor-planned location?
Why this is structural, not individual
The most important misreading of the 50-90 % abandonment figure is to treat it as evidence that the student “wasn’t ready,” “rejected the device,” or “preferred another modality.” The peer-reviewed AAC literature is clear that abandonment is in nearly every case attributable to identifiable failures in the implementation system — vocabulary organization, motor-plan stability, partner training, and continuity of clinical support during transitions (Moorcroft, Scarinci & Meyer, 2019). Light & McNaughton (2014) caution against the “not-ready-for-AAC” framing as a category error: communicative competence is built by AAC use, not pre-required for it.
The implication for districts and IEP teams is that abandonment is a process indicator on the system, not on the student. The three signals above are all observable in the service-delivery record without any assessment of the student.
Equity guard — presume competence
Romski & Sevcik (2005) and the broader AAC literature converge on the principle of presumed competence: the AAC system must be designed for the student to develop into, not for the team’s current estimate of the student’s capacity. Restricting vocabulary based on perceived ability — limiting the display to nouns, removing core words, configuring only for single-word labeling — is itself a documented driver of abandonment because it produces a system that cannot deliver the communication outcomes that motivate continued use. Robust vocabulary on day one is the equity intervention. Limited-vocabulary “starter” systems are not.
What changes operationally
The shift is from one-time AAC procurement (the device is delivered, the student is configured, the case is closed) to continuous service-delivery audit on three structural dimensions. Has core vocabulary moved position? Has every adult in the communication environment had partner instruction in the last twelve months? Does the home-screen display include an organized core section with motor-planned locations? Each of these is a yes/no field check on records the school SLP, AT specialist, or AAC vendor already maintains.
The deliverable is not a re-evaluation of the student. It is a queue of three structural questions that the responsible adult should answer before the next IEP review.
Disclaimer. This brief is a research-informed analysis of published peer-reviewed AAC research and clinical reference literature. It is not a clinical recommendation for any specific student or device. AAC selection, configuration, and implementation require the involvement of a qualified speech-language pathologist with AAC training, often in collaboration with an assistive-technology specialist; this brief is intended to inform the structural questions IEP teams ask, not to substitute for that expertise.
References
- Banajee, M., Dicarlo, C., & Stricklin, S.B. (2003). Core vocabulary determination for toddlers. Augmentative and Alternative Communication, 19(2), 67-73.
- Johnson, J.M., Inglebret, E., Jones, C., & Ray, J. (2006). Perspectives of speech-language pathologists regarding success versus abandonment of AAC. Augmentative and Alternative Communication, 22(2), 85-99.
- Kent-Walsh, J., Murza, K.A., Malani, M.D., & Binger, C. (2015). Effects of communication partner instruction on the communication of individuals using AAC: A meta-analysis. Augmentative and Alternative Communication, 31(4), 271-284.
- Light, J., & McNaughton, D. (2014). Communicative competence for individuals who require AAC: A new definition for a new era of communication? Augmentative and Alternative Communication, 30(1), 1-18.
- Light, J., Wilkinson, K.M., Thiessen, A., Beukelman, D.R., & Fager, S.K. (2019). Designing effective AAC displays for individuals with developmental or acquired disabilities: State of the science and future research directions. Augmentative and Alternative Communication, 35(1), 42-55.
- Millar, D.C., Light, J.C., & Schlosser, R.W. (2006). The impact of augmentative and alternative communication intervention on the speech production of individuals with developmental disabilities: A research review. Journal of Speech, Language, and Hearing Research, 49(2), 248-264.
- Moorcroft, A., Scarinci, N., & Meyer, C. (2019). A systematic review of the barriers and facilitators to the provision and use of low-tech and unaided AAC systems for people with complex communication needs and their families. Disability and Rehabilitation: Assistive Technology, 14(7), 710-731.
- Romski, M., & Sevcik, R.A. (2005). Augmentative communication and early intervention: Myths and realities. Infants & Young Children, 18(3), 174-185.
- Sennott, S.C., Light, J.C., & McNaughton, D. (2016). AAC modeling intervention research review. Research and Practice for Persons with Severe Disabilities, 41(2), 101-115.
- Thistle, J.J., & Wilkinson, K.M. (2015). Building evidence-based practice in AAC display design for young children: Current practices and future directions. Augmentative and Alternative Communication, 31(2), 124-136.
- United Nations Convention on the Rights of Persons with Disabilities (2006), Article 21.