by Margaret Edwards, MA, MEd, CCC-SLP (Speech-Language Pathologist); NWACS Contributor
We are most familiar with using Augmentative/Alternative Communication (AAC) with a student who can point. This student typically uses their finger to directly activate a button on their AAC system. What happens when a student cannot point? How will they access their AAC system?
This is the perfect time to consider scanning. This option is used for students who are unable to directly select a button by touching the screen/board. For a formal definition, I’ll go back to Beukelman and Mirenda (2005) who describe scanning as an individual having to “wait while the facilitator or electronic device scans through undesired items before reaching the item of choice”. Selections are usually made via use of a switch. There are different types of scanning patterns, and that’s what I’d like to discuss, along with the pros and cons of each.
CIRCULAR SCANNING: This is when the items to be selected are presented in a circle, similar to numbers on a clock. The scanner moves from one item to the next. The user must stop the scan when they hear or see the pointer pause on the desired item. I do not have any personal experience using this type of scanning. However, Beukelman and Mirenda (2005) explain a positive of this type of scanning is that it is relatively easy to master.
PRO: easier to cognitively master
CON: small set of items to choose from
LINEAR SCANNING: I have used this type of scanning with students and guess that many SLPs choose this pattern. With the linear scan, the buttons are presented in rows/columns. Each button is highlighted/spoken, going through each row until the desired item is selected. Here is an example of a device that is programmed to linear scan.
PRO: items are selected one at a time which may be more straight forward than group scanning (see below)
CON: potentially can take longer for a user to get to their selection
GROUP ITEM SCANNING: When an AAC device is set up with rows and columns, it can be set to scan an entire row first, by highlighting the row. The scanning will then jump to the entire second row. When the user sees the item they want in the highlighted row, they select this row. The device will then linear scans each item in that row until the user selects the desired item. Here is an example of group scanning (called ‘blocks’ in this video).
Most devices allow for adjustment of the scanning speed. For example, in Proloquo2Go under Access Method and Scanning, there is an option to select the scan rate.
Finally, there needs to be a decision made for Automatic scanning, Inverse Scanning, or Step Scanning.
Initially, setting up an AAC device for scanning can seem overwhelming. However, with practice it gets easier and can be very beneficial for students who are unable to directly access their AAC system.
Remember the first time you set up scanning for a student? Share a bit of your story in the comments.
Beukelman, D. & Mirenda, P. (2005). Augmentative & Alternative Communication. Baltimore, MA: Paul H. Brookes Publishing Co.