Investigation of Resource Allocation in Persons with Aphasia for AAC-Related Tasks

This study investigated resource allocation abilities in persons with aphasia (PWA) in the presence and absence of competing stimuli across a series of experimental tasks that involved identifying and selecting single symbols and subject-verb-object (SVO) sentences on a speech generating device (SGD). Participants included 10 individuals with Broca’s aphasia and a group of 10 typical individuals matched on assigned variables. A mixed-group design was used to compare the performance of the two groups on single symbol and SVO sentence accuracy and response latency measures. Data were analyzed using a repeated-measures analysis of variance (ANOVA).
The results revealed that PWA accurately identified significantly (p <.01) fewer single symbols and SVO sentences in comparison to matched control participants. Additionally, number of symbols per screen and level of location of symbols had a significant effect (p <.01) on accuracy of responses for both groups. Furthermore, there was a significant (p <.05) interaction between the listening condition and group variables, indicating that competing stimuli have the potential to slow down the processing of information for PWA. Analysis of response latencies indicated that PWA exhibited longer response latencies across all three listening conditions in contrast to control participants. A significant negative correlation (p <.05) was observed between accuracy of responses for the single symbol and SVO sentence tasks and perceptual ratings of task difficulty. In summary, the results of this study indicate that effective and efficient use of SGDs by PWA depends upon several vocabulary organization factors such as the number of symbols on a screen and the specific location of a symbol across several screens. These results suggest that researchers and clinicians may need to consider organizing vocabulary on SGDs in such a manner as to reduce the cognitive demands placed on PWA.