Least-to-most (LTM) prompting, is a teaching method that starts with giving the learner a natural cue or hint and then gradually provides more helpful prompts if needed until the learner successfully demonstrates the skill (Ault & Griffen, 2013). In this approach, the instructor initially allows the learner a brief period to respond on their own. If the learner does not respond, the instructor offers the least intrusive prompt, such as a gentle reminder. If the learner still needs more help, more direct prompts (e.g., verbal prompt, gesture prompt) are provided as necessary to guide them through each session (Libby, 2008).
Least-to-most (LTM) prompting approach is a helpful method for teaching children with Autism Spectrum Disorder (ASD) who use Augmentative and Alternative Communication (AAC) to develop their language skills, especially when progressing to using multi-symbol messages. This technique involves giving initial natural cues to encourage the child to use their skills independently. If the child needs more help, the instructor gradually provides more direct prompts to guide them, ensuring that they eventually achieve the target skill (Ault & Griffen, 2013; Neitzel & Wolery, 2009).
In using the least-to-most (LTM) prompting procedure, several strategies are systematically implemented to support learning. These include verbal prompting, where the instructor asks a question to guide the child; verbal cueing, which involves requesting a specific response and modeling, which shows how to use a device. Additionally, the instructor can incorporate other types of prompts such as a small time delay (allowing time for the child to respond on their own) verbal modeling (providing a spoken example of the target response) or physical guidance to further assist the child in learning (Finke et al., 2017).
Study Overview:
This study focused on three boys with Autism Spectrum Disorder (ASD) and developmental disabilities, assessing their use of an iPad-based speech-generating device (SGD) to enhance communication skills. The intervention targeted the improvement of the boys' ability to make multi-word requests using the Proloquo2Go AAC system, while reducing maladaptive behaviours and promoting generalisation across settings and items.
Intervention Goals:
Teach the boys to request preferred items using the Proloquo2Go AAC system with two- and three-word sentences.
Increase both independent non-vocal and vocal requesting to improve communication precision.
Reduce maladaptive behaviours such as crying and pointing by replacing them with functional requests.
Promote generalisation of AAC-based requesting skills to other preferred items and settings.
Pre-session set-up: Prior to each session, the iPad with the Proloquo2Go app was placed within the children’s reach, with the initial screen displaying symbols related to requests (e.g., “I want to”). The iPad and preferred items were positioned to ensure visibility and accessibility.
Instructional Procedures:
Prompt 1: Natural Cue:
The instructor initiated the session by asking, "What do you want?" to prompt a request from the child.
Prompt 2: Verbal Prompt:
If no request was made within 5 seconds, a verbal prompt (e.g., “Touch chips”) was provided to guide the child’s response.
Prompt 3: Gestural Prompt:
If the child still does not respond after another 5 seconds, the instructor provides a gestural prompt by pointing to the SGD, such as pointing to the correct icon.
Prompt 4: Partial Physical Prompt:
If the child did not independently activate the SGD within 5 seconds, the instructor uses the least amount of physical guidance necessary to help the child touch the symbol and activate the speech output.
This step aligns with partial physical prompting by guiding the child's hand to the SGD, allowing for minimal assistance.
Feedback and Reinforcement:
Correct requests are immediately reinforced with praise and access is given to the requested item for 30 seconds, accompanied by a relevant statement like “Good job! You said eat chips,” in an enthusiastic voice.
For prompted responses, less enthusiastic feedback is given, such as in a monotone voice: “Good job, you said eat chips,” along with 15 seconds of access to the requested item.
Prompt Fading:
Prompts are systematically faded as the child becomes more proficient, reducing from physical guidance to no prompts during the maintenance phase.
This prompt fading encourages independent use of the SGD, as the intervention moved from using physical prompts to completely removing prompts.
Maintenance and Generalization:
To ensure the generalization of the requesting skill, one week after the intervention, sessions are conducted to assess the maintenance of requesting skills without prompts and in different contexts. The child is exposed to new items and communication partners, ensuring that the requesting behaviour generalized across different settings and people.
The continued reinforcement and support across different contexts (toys, snacks and applications) helps solidify the use of the SGD for communication beyond the initial setting.
Ault, M. J., & Griffen, A. K. (2013). Teaching with the system of least prompts: An easy method for monitoring progress. Teaching Exceptional Children, 45, 46–53
Finke, E. H., Davis, J. M., Benedict, M., Goga, L., Kelly, J., Palumbo, L., ... & Waters, S. (2017). Effects of a least-to-most prompting procedure on multisymbol message production in children with autism spectrum disorder who use augmentative and alternative communication. American Journal of Speech-Language Pathology, 26(1), 81-98. https://doi.org/10.1044/2016_AJSLP-14-0187
Libby, M. E., Weiss, J. S., Bancroft, S., & Ahearn, W. H. (2008). A comparison of most-to-least and least-to-most prompting on the acquisition of solitary play skills. Behaviour Analysis in Practice, 1(1), 37–43. https://doi.org/10.1007/BF03391719
Muharib, R., Alzrayer, N. M., Wood, C. L., & Voggt, A. P. (2019). Backward chaining and speech-output technologies to enhance functional communication skills of children with autism spectrum disorder and developmental disabilities. Augmentative and Alternative Communication, 35(4),251-262. https://doi.org/10.1080/07434618.2019.1704433
Neitzel, J., & Wolery, M. (2009). Steps for implementation: Leastto-most prompts. Chapel Hill, NC: National Professional Development Center on Autism Spectrum Disorders, Frank Porter Graham Child Development Institute, University of North Carolina