Divided-Attention and Directed-Attention Listening Modes in Children with Dichotic Deficits: An Event-Related Potential Study

Abstract

Dichotic listening (DL) procedures are commonly employed in the evaluation of auditory processing in children. Review of the various clinical tests reveals considerable diversity in both the signals employed and their mode of administration. The extent to which other non auditory-specific factors influence the test outcome is often difficult to determine. Individual differences in memory, attention, facility with test stimuli, and report strategy are always of potential concern in the interpretation of results. In the present study, we examined behavioral and electrophysiological (ERP) responses for 20 children during two DL tasks. Two groups of children were evaluated. One group was comprised of children who showed substantial ear differences on clinical measures of DL; the other group showed no such deficits and served as age-matched controls. In one of the DL tasks, participants monitored dichotic stimuli using the divided-attention (unfocused) mode. In the other DL task, a directed-attention (focused) mode was employed. Both tasks involved simple "same-different" judgments for real words presented in a basic reference-probe paradigm. We purposefully sought an easy DL task in order to minimize the number of extra-auditory factors influencing their performance. For control purposes, a diotic procedure involving the same stimuli was also included. Results showed that the amplitude of the elicited late-positive component (LPC) was smaller and prolonged in latency for the group of poor listeners as compared to the control group. This finding occurred only when dichotic stimuli were presented in the divided-attention mode. When participants directed their attention to a single side, or when listening in a diotic mode, the LPC for both groups was more similar. Group differences in the N400 component were apparent for both listening tasks. Results are discussed in relation to an inability of some children to inhibit processing of unattended auditory information. Implications for the clinical administration of dichotic listening tests are also discussed.

Attentional Capacity Limits Gap Detection during Concurrent Sound Segregation

“…Such a competition for attention among multiple auditory objects could account for the reduced LPC amplitude. This interpretation is consistent with prior studies showing a reduced LPC under the influence of competitive interference between concurrent stimuli (Martin, Jerger, & Mehta, 2007;Fischler & Bradley, 2006). This phenomenon is also consistent with Wicken's attentional resource model in which attention is divided among mental operations, which impairs performance task demands (Wickens, 1976(Wickens, , 2008.…”

“…The participants might have adopted the strategy to keep their attention focused on the tuned harmonic. Previous findings have shown that the LPC amplitude was greater in conditions where participants were asked to focus their attention to a particular stimulus than in conditions where focused attention to that particular stimulus was not required in active listening tasks (Martin et al, 2007). To verify this possibility, future studies may consider comparing LPC amplitudes during gap detection, with the gap having equal probability of being inserted in the tuned and mistuned components of a sound complex.…”

Auditory Processing Theories of Language Disorders: Past, Present, and Future

“…The middle latency response, from approximately 12 ms to 50 ms poststimulus onset, is probably generated by the upper brainstem and primary auditory cortex and is followed by "later" cortical responses 50-250 ms after stimulus onset (Hall, 1992). Both ABRs and cortical responses have been used in investigations of auditory processing in children with APD, SLI, and dyslexia (e.g., Basu, Krishnan, & Weber-Fox, 2010;Bishop & McArthur, 2005;Jerger, Martin, & McColl, 2004;Jirsa, 1992;Jirsa & Clontz, 1990;Marler & Champlin, 2005;Martin, Jerger, & Mehta, 2007;McArthur, Atkinson, & Ellis, 2009;Sharma et al, 2006).…”

Auditory-cognitive interactions underlying interaural asymmetry in an adult listener: A case study

“…Word stimuli were selected from a larger body of words used in a previous study (Martin et al, 2007). The speech stimuli were recorded in an audiometric sound-treated room by an adult male, monolingual speaker of English.…”