Effect of Number of Graphic Symbols, Levels, and Listening Conditions on Symbol Identification and Latency in Persons with Aphasia.

This study investigated the ability of persons with aphasia to complete a series of experimental tasks involving single symbol and subject-verb-object sentence identification on a speech-generating device (SGD) in the presence/absence of competing stimuli. In all, 10 persons with Broca's aphasia and 10 persons in the control group were compared on accuracy and response latency of symbol identification across three listening conditions. Persons with aphasia identified fewer symbols accurately and had longer response latencies than persons in the control group. Number of symbols on the screen and location level had a significant effect on accuracy and latency for both groups. Persons with aphasia perceived tasks to be more difficult than persons in the control group. Results indicate that effective use of SGDs by persons with aphasia may depend on several message organization factors including location and number of symbols per screen.