Switches - Scanning
A switch is a device that allows a user to indirectly activate a device (Coyne, 2004). Switches are typically used by individuals with physical or intellectual disabilities to make it easier for them to use communication or other electronic devices (Coyne). They are often described as augmentative and alternative communication devices. There are three main methods of interacting with a switch: buttons, joysticks, and scanning. There are also newer technologies which include head-controlled interfaces and tools that user’s can interact with using their eyes, mouths, feet, among others (Shih & Shih, 2009); however, there is less research examining these tools.
Switches require a number of abilities in order for a user to operate them, including: waiting for the correct moment to activate the switch, the ability to activate the switch and hold it in an activated position, releasing the switch, waiting again, and activating the switch again as appropriate (Beukelman & Mirenda, 2013). Therefore, the individual’s physical and intellectual abilities need to be considered when choosing the correct type of switch.
Switch scanning involves a device or software automatically and systematically visiting all items that can be selected on a screen one at a time, followed by the user triggering a switch activation (e.g., a button) when the desired item is highlighted (Leung, Brian, & Chau, 2013). Although scanning is often combined with button switches, it may be slow and inefficient for users (Ka, Simpson, & Chung, 2012). There are different methods of scanning reviewed in the research literature, but no conclusions about the best method can be made at this time (Blackstein-Adler, Stein, Quintal, Birch, & Weiss, 2004). Further, there is limited research examining the success of switches compared to other augmentative and alternative communication devices, but there have been studies comparing types of switches to each other (e.g., Cole & Swinth, 2004) or case studies examining an individual users’ success using a switch (e.g., Blackstein-Adler et al., 2004). Due to this limited research, individuals should work with an Occupational Therapist to determine the best style of switch for their specific needs.
Because of the expense associated with switches, some researchers and developers have started to look for more widely available options, and have adapted other tools such as computer mouses (Shih & Shih, 2009) or Wii Nunchuks (Standen et al., 2011) to be used as switches. Standen and colleagues found that there were no significant differences among the participants’ performance when using their familiar switch device compared to the Wii Nunchuks, which demonstrates the exciting possibility of future availability of more inexpensive devices for individuals with disabilities. Unfortunately, at this time switches are not optimized for mobile devices and more research is required (Fager et al., 2012).
Research Rating: Due to the lack of peer-reviewed experimental research, the claims made by the developers of these products may not be reliable or valid. It should be noted that there have been a number of case studies completed; however, it is not clear how well this information generalizes to other individuals.
May be the only way than an individual can interact with a device; allow individuals with physical or intellectual disabilities to communicate or interact with their environment (Coyne, 2004)
Widely available tools (e.g., Wii Nunchuk) can be adapted to be used as switches, decreasing the cost and increasing availability (Standen et al., 2011)
There is a wide variety of styles of switches, which allows them to be tailored to each individual’s specific needs and preferences (Cole & Swinth, 2004)
Windows and Mac operating systems come pre-loaded with on-screen keyboard options that can be switch controlled (Schaefer & Andzik, 2016)
There may be little support for individuals and these devices may be hard to integrate into day-to-day life, which may contribute to abandonment of these devices (Leung et al., 2013)
May require intensive training over a long period of time (Schaefer & Andzik, 2016)
Can be very expensive and difficult to acquire (Shih & Shih, 2009)
Switches should be tailored to each individual’s specific strengths and needs (Cole & Swinth, 2004). Contact an Occupational Therapist to determine which system and what settings are the most appropriate.
Special Consideration: Workflow
Exact prices change frequently, which is why only approximate ranges are listed.
$ - Under $5
$$ - Between $6 and $50
$$$ - Between $51 and $250
$$$$ - Over $250
Beukelman, D. R., & Mirenda, P. (2013). Augmentative and Alternative Communication: Supporting Children and Adults with Complex Communication Needs: Paul H. Brookes Pub.
Blackstein-Adler, S., Stein, F., Quintal, J., Birch, S., & Weiss, P. L. T. (2004). Mouse manipulation through single switch scanning. Assistive Technology, 16, 28-42.
Cole, J., & Swinth, Y. (2004). Comparison of the TouchFree switch to a physical switch; Children’s abilities and preferences: A pilot study. Journal of Special Education Technology, 19, 19-30.
Coyne, D. (2014). Augmentative and alternative communication (AAC) guidelines for speech pathologists
who support people with disability. Retrieved from http://www.adhc.nsw.gov.au/__data/assets/file/0011/302402/Augmentative_and_Alternative_Communication_Practice_Guide.pdf
Fager, S., Beukelman, D. R., Fried-Oken, M., Jakobs, T., & Baker, J. (2012). Access interface strategies. Assistive Technology: The Official Journal of RESNA, 24, 25-33.
Ka, H. W., Simpson, R., & Chung, Y. (2012). Intelligent single switch wheelchair navigation. Disability and Rehabilitation: Assistive Technology, 7, 501–506.
Leung, B., Brian, J. A., & Chau, T. (2013). Learning and mastery behaviours as risk factors to abandonment in a paediatric user of advanced single-switch access technology. Disability and Rehabilitation: Assistive Technology, 8, 426-433.
Schaefer, J. M., & Andzik, N. R. (2016). Switch on the learning: Teaching students With significant
disabilities to use switches. Teaching Exceptional Children, 48, 204-212.
Shih, C., & Shih, C. (2009). Development of a computer input system for people with disabilities
using a commercial mouse and switches. Disability and Rehabilitation: Assistive Technology, 4, 414–421.
Standen, P. J., Camm, C., Battersby, S., Brown, D. J., & Harrison, M. (2011). An evaluation of the Wii Nunchuk as an alternative assistive device for people with intellectual and physical disabilities using switch controlled software. Computers and Education, 56, 2-10.
Written by Bronwyn Lamond, Last Revision May 2018