Comparison of relative demands implicated in direct selection and scanning: Considerations from normal children

Abstract

The relative demand of the two physical access techniques of direct selection and row column scanning was compared across 100 normal children: 20 each in grades 1 through 5. The children were required to find a specific shape on the 128 target array of the Prentke Romich Light Talker™, using either the optical head pointer to direct select or rocking lever switch to access the row column scan. The direction-following task had four difficulty levels. Performance on the task was measured by the number of errors. Analysis of variance results indicated that the subjects made significantly more errors when using row column scanning than when using direct selection. Furthermore, there was a significant increase in errors with an increase in difficulty level and a decrease in errors with an increase in grade level. In general, the results substantiated previous speculations that row column scanning is a more difficult task than direct selection. Clinical implications and suggestions for future research are addressed.

• direct selection
• message selection techniques
• row column scanning