Comparisons of five symbol assessment protocols with nondisabled preschoolers and learners with severe intellectual disabilities

Abstract

This report includes the results of two related experiments designed to compare five commonly used symbol assessment protocols. In the first experiment, five assessment tasks incorporating real objects and colored photographs were given to 25 preschoolers (age 26–41 months) without disabilities of any kind. In the second experiment, the same five protocols were administered to 20 learners with severe intellectual disabilities (age 7–21 years) who had varying levels of verbal labeling comprehension. The experiments compared the subjects' scores on the five assessment tasks, which included four visual matching protocols and one verbal matching protocol. The results of Experiment 1 (nondisabled preschoolers) indicated that the five protocols were equivalent. The results of Experiment 2 (learners with severe intellectual disabilities) indicated that there were significant differences across both subject groups and protocols. Two of the visual matching protocols appeared to differ in difficulty across all subjects, and the verbal label matching protocol was significantly more difficult for the subjects who did not have verbal label comprehension abilities. The results are discussed in terms of the generalizability of research using nondisabled subjects and their implications for symbol assessment and intervention in AAC.

• severe disability
• symbol assessment
• symbols