Biomedical subjects

G M McArthur

Publications and source records attributed to G M McArthur.

8 recordsLinked to original sources

PubMed2005

Speech and non-speech processing in people with specific language impairment: a behavioural and electrophysiological study.

McArthur and Bishop (2004) found that people with specific language impairment (SLI) up to 14 years of age have poor behavioural frequency discrimination (FD) thresholds for 25-ms pure tones, while people with SLI upto 20 years of age have abnormal auditory N1--P2--N2 event-related potential (ERP) responses to the same tones. In the present study, we extended these findings to more complex non-speech and speech sounds by comparing younger (around 13 years) and older (around 17 years) teenagers with SLI and controls for their behavioural FD thresholds and N1-P2 ERPs to 25 and 250-ms pure tones, vowels, and non-harmonic complex tones. We found that a subgroup of people with SLI had abnormal responses to tones and vowels at the level of behaviour and the brain, and that poor processing was associated with the spectral complexity of auditory stimuli rather than their phonetic significance. We suggest that both the age of listeners and the sensitivity of psychoacoustic tasks to age-related changes in auditory skills may be crucial factors in studies of sound processing in SLI.

Acoustic Stimulation↗

PubMed2005

Electrophysiological evidence implicates automatic low-level feature detectors in perceptual asymmetry.

Perceptual asymmetry has been demonstrated behaviorally using frequency modulated (FM) stimuli: a modulated tone is easier to detect among unmodulated distracters than the converse. We demonstrate perceptual asymmetry for FM tones in the mismatch negativity (MMN) component of the event-related potential, regardless of whether the participant attends to the tones. These results suggest that perceptual asymmetry reflects the automatic activation of low-level feature detectors in the auditory system.

Acoustic Stimulation↗

PubMed2004

Frequency discrimination deficits in people with specific language impairment: reliability, validity, and linguistic correlates.

The reliability and validity of a frequency discrimination (FD) task were tested in 16 people with specific language impairment (SLI) and 16 people with normal spoken language (controls). The FD thresholds of the 2 groups indicated that FD thresholds for 25-ms and 250-ms tones were remarkably stable across 18 months. The FD thresholds were lower for control listeners than for listeners with SLI for both duration conditions, and the FD thresholds for both groups of listeners were lower for 250-ms tones than for 25-ms tones. Moreover, the FD thresholds were influenced little by nonperceptual, task-related abilities (e.g., paired-associative learning, memory for temporal order, sustained attention, and control of attention) of the listener groups. The significant group difference between the mean FD thresholds of the SLI and control groups was explained by a subgroup of people with SLI who had particularly poor thresholds compared with those of controls and the majority of the SLI group. This subgroup did not differ from the remainder of the SLI sample in terms of age or nonverbal ability but was characterized by very poor reading that was associated with poor phonemic awareness.

Adolescent↗

PubMed2004

Immature cortical responses to auditory stimuli in specific language impairment: evidence from ERPs to rapid tone sequences.

Event-related potentials (ERPs) to tone pairs and single tones were measured for 16 participants with specific language impairment (SLI) and 16 age-matched controls aged from 10 to 19 years The tone pairs were separated by an inter-stimulus interval (ISI) of 20, 50 or 150 ms. The intraclass correlation (ICC) was computed for each participant between the ERP to a single tone and the ERP to the tone pair. A high ICC indicates that the brain response to a tone pair is similar to that for a single tone. ICCs were significantly higher at short than at long ISIs. At 50-ms ISI, ICCs were higher for younger than older participants. Age and ISI interacted with SLI status: ERPs of older participants with SLI differed from age-matched controls, and resembled ERPs of younger controls, consistent with a theory of immature auditory processing in SLI.

Acoustic Stimulation↗

PubMed2003

Do video sounds interfere with auditory event-related potentials?

To make the electroencephalogram (EEG) recording procedure more tolerable, listeners have been allowed in some experiments to watch an audible video while their auditory P1, N1, P2, and mismatch negativity (MMN) event-related potentials (ERPs) to experimental sounds have been measured. However, video sounds may degrade auditory ERPs to experimental sounds. This concern was tested with 19 adults who were instructed to ignore standard and deviant tones presented through headphones while they watched a video with the soundtrack audible in one condition and silent in the other. Video sound impaired the size, latency, and split-half reliability of the MMN, and it decreased the size of the P2. However, it had little effect on the P1 or N1 or on the split-half reliability of the P1-N1-P2 waveform, which was significantly more reliable than the MMN waveform regardless of whether the video sound was on or off. The impressive reliability of the P1 and N1 components allows for the use of video sound during EEG recording, and they may prove useful for assessing auditory processing in listeners who cannot tolerate long testing sessions.

Acoustic Stimulation↗

PubMed2001

Auditory backward recognition masking in children with a specific language impairment and children with a specific reading disability.

The auditory backward recognition masking (ABRM) and intensity discrimination (ID) thresholds of children with a specific language impairment and poor reading (SLI-poor readers), children with an SLI and average reading (SLI-average readers), children with a specific reading disability and average spoken language skills (SRD-average language), and children with normal spoken and written language (controls) were estimated with "child-friendly" psychophysical tasks. The pattern of ABRM and ID scores suggests that a subset of children with concomitant oral language and reading impairments has poor ABRM thresholds, and that a subgroup of children with an SLI or SRD has poorer ID thresholds than controls. The latter result warns against using rapid auditory processing tasks that do not actively control for auditory discrimination ability. Further, some unusually poor ABRM scores and ID scores question the validity of extreme scores produced by children on psychophysical tasks. Finally, the poor oral language scores of many of the children who had impaired reading highlight the need to test the oral language skills of SRD samples to ascertain how homogeneous and specifically disabled they really are.

Adolescent↗

PubMed2000

On the "specifics" of specific reading disability and specific language impairment.

The reading and oral language scores of 110 children with a specific reading disability (SRD) and 102 children with a specific language impairment (SLI) indicated that approximately 53% of children with an SRD and children with an SLI could be equally classified as having an SRD or an SLI, 55% of children with an SRD have impaired oral language, and 51% of children with an SLI have a reading disability. Finding that a large percentage of children can be equally classified as SRD or SLI has repercussions for the criteria used to define an SRD, for conceptualising subgroups of learning disability, and for estimates of the incidence of SRD. Further, it highlights the need for future studies to assess both the reading and oral language abilities of SRD and SLI participants to determine how specifically impaired and homogeneous samples really are.

Adolescent↗

PubMedDate not supplied

Auditory perceptual processing in people with reading and oral language impairments: current issues and recommendations.

A popular hypothesis holds that specific reading disability (SRD) and specific language impairment (SLI) result from an impaired ability to process rapid and brief sounds. However, the results of experiments that have tested this hypothesis are incongruous. A number of factors could explain these contradictory findings, including the questionable reliability and validity of rapid auditory processing tasks, individual differences in the auditory processing abilities of SRD and SLI populations, the age of listeners, the quality of control groups, and the relationship between verbal and non-verbal auditory processing abilities. These issues highlight the need for future studies to (1) establish the reliability and validity of psychophysical tasks used to assess rapid auditory processing; (2) report the rapid auditory processing scores of individuals rather than just group means; (3) include a wide range of reading and spoken language tests to determine the literacy and oral language profile of people who demonstrate an auditory processing deficit; (4) include clinical comparison groups to determine whether a rapid auditory processing deficit is related specifically to written and spoken language impairments; and (5) examine the relationship between low-level non-verbal, verbal, and phonological processing abilities.

Child↗