Functional Performance Using Eye Control and Single Switch Scanning by People With ALS

Abstract

Eye control and switch scanning are commonly considered as augmentative and alternative communication (AAC) access options by people with amyotrophic lateral sclerosis (ALS) at the same clinical intervention point. Choosing optimal access methods must be supported by performance and qualitative feedback, as well as considerations of cognitive changes sometimes associated with ALS. We present quantitative and qualitative data comparing access methods used by five people with ALS and five adults without ALS. Each participant accessed an on-screen keyboard during repeated exposure to two conditions: single switch scanning and eye control. Participants were required to copy sentences presented on a computer screen. Keyboard letter organization was held constant between conditions, and rate enhancement and word prediction techniques were not used. Measures of speed and accuracy revealed a significant speed advantage for eye control and a significant accuracy advantage for single switch scanning. Speed and accuracy for both access methods improved with practice. Predictably, people with ALS performed significantly slower than participants without ALS using both access methods. Participants rated eye control as the more efficient access method overall. Participants without ALS rated both access methods significantly more fatiguing than people with ALS. Post study interviews revealed that eye control was the preferred access option for people with ALS. Clinical implications and extensions of this study are discussed.