Aphasia and auditory extinction: Preliminary evidence of binding.

Background: McNeil, Odell, and Tseng (1991), and Murray and colleagues (Murray, 2000; Murray, Holland, & Beeson, 1997a, 1997b) have suggested that variability of performance in patients with aphasia may be due to nonlinguistic cognitive variables, such as attention (i.e., resources, capacity, effort), which affect language comprehension and production. Given the research that has supported the relationship between aphasia and attention deficits, it is important to determine what effect this breakdown in attention may have on cognitive processes for individuals with aphasia.Aims: This study aims to determine if auditory extinction is present in individuals with aphasia, and if so, if this is due to a breakdown in binding. If extinction is found for individuals with aphasia, it would further support the notion that auditory attention difficulties are present among individuals with aphasia, since visual and auditory research has attributed extinction to a breakdown in attention (Baylis, Driver, & Rafal, 1993; Deouell, Bentin, & Soroker, 2000; Deouell & Soroker, 2000). If binding is found to be deficient, the fact that individuals with both left and right hemisphere lesions demonstrate this phenomenon would lead to a number of implications regarding the relationship of attention and aphasia.Methods & Procedures: Auditory extinction, in which one stimulus is not perceived during double simultaneous stimulation (DSS) presentation, was examined in six individuals with aphasia (aged 42-74 years) and six age-matched healthy adults. Two different experiments were conducted in which the auditory stimuli, consisting of male and female voices speaking the letters "T" or "O", were systematically varied to investigate whether binding of identification to location contributes to extinction.Outcomes &
Results: Participants with aphasia made more omission errors (extinction) than the control group, and extinction was significantly greater for binding versus nonbinding conditions, suggesting that binding may play a role in extinction for individuals with aphasia.Conclusions: These data provide preliminary results that auditory extinction exists in individuals with aphasia and may be due to deficits in binding together identification and localisation information. Research on this phenomenon and how it influences language would be a worthwhile endeavour for future studies. Moreover, little is known about assessment of auditory attention in patients with aphasia. Further research in this area can lead to advancements in theoretical and functional assessment for individuals with aphasia who have auditory attention and/or binding deficits and require speech-language pathology intervention.