Enhancing Performance with Single-switch Scanning

In a recent Phase I SBIR project, we developed a method for adjusting a single-switch scanning interface to increase a user's text entry rate (TER). We evaluated that method with nine individuals who use single-switch scanning to communicate. Text entry rates improved by an average of 120% (p=.003). All nine subjects increased their TER by at least 40% and five of the nine increased their TER by over 100%.

Example of single-switch scanning display
Fig 1. Example of a group-row-column scanning display. It includes 8 groups, scanned in the following order: (1) titlebar, (2) message window, (3) pronouns, (4) helping verbs, (5) letters+prediction, (6) verbs, (7) chat, (8) prepositions. Once a group is selected, scanning continues through rows, and then columns, of that group.

Results from this work were published in the Journal of Rehabilitation Research and Development, and we began Phase II research on this project in early 2015. We're interested in any feedback you may have on these results or our method for adjusting scanning systems. Feel free to comment on our blog post, or contact us.


  1. Koester HH, Simpson R. (2014). A Method for Enhancing Text Entry Rate with Single-switch Scanning. Journal of Rehabilitation Research and Development, 51(6): 995-1012.
  2. Koester HH, Simpson RC. (2014). A Method for Enhancing Text Entry Rate with Single-switch Scanning. Workshop presented at RESNA 2014 Annual Conference, Indianapolis, IN.
  3. Mankowski R, Simpson R, Koester HH. (2013). Validating a Model of Row-Column Scanning. Disability and Rehabilitation: Assistive Technology, 8(4):321-9. [abstract]
  4. Simpson R, Mankowski R, Koester HH. (2011). Modeling One-Switch Row-Column Scanning with Errors and Error Correction Methods. The Open Rehabilitation Journal, Vol. 4: 1-12.
  5. Simpson R, Koester HH, LoPresti E. (2007). Selecting an Appropriate Scan Rate: The .65 Rule. Assistive Technology, 19(2):51-58. [abstract]

For a full listing of all of our research publications, visit the Publications page.

Funded By

We thank the following funding agencies for their support, as well as the participants in our studies.