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Purpose: Continuous performance tasks (CPTs) are used to measure individual differences in sustained attention. Many different stimuli have been used as response targets without consideration of their impact on task performance. Here, we compared CPT performance in typically developing adults and children to assess the role of stimulus processing on error rates and reaction times. Method: Participants completed a CPT that was based on response to infrequent targets, while monitoring and withholding responses to regular nontargets. Performance on 3 stimulus conditions was compared: visual letters (X and O), their auditory analogs, and auditory pure tones. Results: Adults showed no difference in error propensity across the 3 conditions but had slower reaction times for auditory stimuli. Children had slower overall reaction times. They responded most quickly to the visual target and most slowly to the tone target. They also made more errors in the tone condition than in either the visual or the auditory spoken CPT conditions. Conclusions: The results suggest error propensity and reaction time variations on CPTs cannot solely be interpreted as evidence of inattention. They also reflect stimulus-specific influences that must be considered when testing hypotheses about modality-specific deficits in sustained attention in populations with different developmental disorders.

Purpose: Continuous performance tasks (CPTs) are used to measure individual differences in sustained attention. Many different stimuli have been used as response targets without consideration of their impact on task performance. Here, we compared CPT performance in typically developing adults and children to assess the role of stimulus processing on error rates and reaction times. Method: Participants completed a CPT that was based on response to infrequent targets, while monitoring and withholding responses to regular nontargets. Performance on 3 stimulus conditions was compared: visual letters (X and O), their auditory analogs, and auditory pure tones. Results: Adults showed no difference in error propensity across the 3 conditions but had slower reaction times for auditory stimuli. Children had slower overall reaction times. They responded most quickly to the visual target and most slowly to the tone target. They also made more errors in the tone condition than in either the visual or the auditory spoken CPT conditions. Conclusions: The results suggest error propensity and reaction time variations on CPTs cannot solely be interpreted as evidence of inattention. They also reflect stimulus-specific influences that must be considered when testing hypotheses about modality-specific deficits in sustained attention in populations with different developmental disorders., Attention is a complex construct that has been implicated in disorders such as attention-deficit/ hyperactivity disorder (ADHD). Of the many tasks developed to assess different aspects of attention, the continuous [...]

Sensitivity to lexical stress in adult German-speaking students with reading difficulty was investigated using minimal pair prepositional verbs whose meaning and syntax depend on the location of the stressed syllable. Two tests of stress perception were used: (i) a stress location task, where listeners indicated the location of the perceptually most prominent syllable, and (ii) a stress pattern identification task, where listeners indicated if the stress pattern was appropriate for its semantic frame. The students with reading difficulties performed worse than the normally reading students on both tasks. Their poorer performance did not reflect the lack of a percept for lexical stress rather patterns of performance across the two tasks suggested that each loaded onto different underlying cognitive abilities. Deficits in these, rather than perceptual difficulties, explained observed group differences. Students with reading difficulties have a normal implicit knowledge of lexical stress usage but lack the necessary cognitive resources for developing an explicit metalinguistic awareness of it. Deficits in these skills not deficiencies in lexical stress perception are implicated in their reading difficulties. (Contains 4 figures and 5 tables.)

Verbal short-term memory (VSTM) is thought to play a critical role in language learning. It is indexed by the nonword repetition task where listeners are asked to repeat meaningless words like "blonterstaping". The present study investigated the effect on nonword repetition performance of differences in efficiency of functioning of some part of the neural architecture mediating VSTM. Hypotheses were stated within Baddeley and Hitch's (1974) multicomponent model of VSTM, with respect to regions of the brain known to be active during tasks tapping into VSTM. We were specifically interested in activations associated with the posterior planum temporale (Spt) which emerge during rehearsal since this region is hypothesized to be central to VTSM (Buchsbaum, Olsen, Koch, & Berman, 2005a). Participants performed a delayed reaction time task in the scanner which explicitly mimicked the three main stages of information-processing involved in VSTM (encoding, rehearsal, recall (here recognition)). The data for each stage were then convolved with scores from a separately measured nonword repetition task. Rather than observing a pattern of individual differences located to specific regions specialized for supporting VSTM, a dissociation in direction of correlation in overlapping regions of the brain was observed during encoding and recognition. Larger hemodynamic responses during encoding were associated with better nonword repetition, and vice versa during recognition. There was little evidence for a network of activations specialized for VSTM. Instead, the main correlations were observed in regions also known to be involved in long-term memory. It seems that individuals who are better at nonword repetition and hence at language learning, activate these regions more efficiently than poorer nonword-repeaters early after stimulus input. These observations are discussed with respect to various models proposed for explaining the phenomenon of VSTM. (Contains 5 tables and 4 figures.)

Behavioural and electrophysiological studies give differing impressions of when auditory discrimination is mature. Ability to discriminate frequency and speech contrasts reaches adult levels only around 12 years of age, yet an electrophysiological index of auditory discrimination, the mismatch negativity (MMN), is reported to be as large in children as in adults. Auditory ERPs were measured in 30 children (7 to 12 years), 23 teenagers (13 to 16 years) and 32 adults (35 to 56 years) in an oddball paradigm with tone or syllable stimuli. For each stimulus type, a standard stimulus (1000 Hz tone or syllable [ba]) occurred on 70% of trials, and one of two deviants (1030 or 1200 Hz tone, or syllables [da] or [bi]) equiprobably on the remaining trials. For the traditional MMN interval of 100-250 ms post-onset, size of mismatch responses increased with age, whereas the opposite trend was seen for an interval from 300 to 550 ms post-onset, corresponding to the late discriminative negativity (LDN). Time-frequency analysis of single trials revealed that the MMN resulted from phase-synchronization of oscillations in the theta (4-7 Hz) range, with greater synchronization in adults than children. Furthermore, the amount of synchronization was significantly correlated with frequency discrimination threshold. These results show that neurophysiological processes underlying auditory discrimination continue to develop through childhood and adolescence. Previous reports of adult-like MMN amplitudes in children may be artefactual results of using peak measurements when comparing groups that differ in variance. (Contains 2 tables and 8 figures.)

Some children with autism demonstrate poor nonword repetition--a deficit considered to be a psycholinguistic marker of specific language impairment (SLI). The present study examined whether there is an SLI subtype among children with autism. We compared the language abilities of children with SLI (n = 34, M age = 11;10 S.D. = 2;3), and children with autism with (Apoor, n = 18, M age = 10;11 S.D. = 3;1) and without (Aapp, n = 16, M age = 10;8 S.D. = 2;7) structural language difficulties. Participants were administered battery of standardized language and memory tests. Although there were some similarities in the language profile of the SLI and Apoor groups, the two groups differed on the tests of oromotor ability and verbal short-term memory and showed a different pattern of errors on the nonword repetition task. These findings providing evidence against the idea of an SLI subtype in autism. Further analyses suggested that the nonword repetition deficits experienced by some children with autism may arise when there is substantial impairment in multiple autistic domains. Learning outcomes: Readers will be introduced to (a) the current state of behavioral, cognitive and genetic research that has investigated the relation between SLI and autism, and (b) three hypotheses of why there exists similarity in the language characteristics of children with SLI and autism. Readers will then be taken through a detailed comparison of the language and memory abilities of group of children with each diagnosis. A theoretical model that seeks to explain the relation between these two disorders will be discussed.

In a previous behavioral study, we showed that parents of children with SLI had a subclinical deficit in phonological short-term memory. Here, we tested the hypothesis that they also have a deficit in nonverbal auditory sensory memory. We measured auditory sensory memory using a paradigm involving an electrophysiological component called the mismatch negativity (MMN). The MMN is a measure of the brain's ability to detect a difference between a frequent standard stimulus (1000Hz tone) and a rare deviant one (1200Hz tone). Memory effects were assessed by varying the inter-stimulus interval (ISI) between the standard and deviant. We predicted that parents of children with SLI would have a smaller MMN than parents of typically developing children at a long ISI (3000ms), but not at a short one (800ms). This was broadly confirmed. However, individual differences in MMN amplitude did not correlate with measures of phonological short-term memory. Attenuation of MMN amplitude at the longer ISI thus did not provide unambiguous support for the hypothesis of a reduced auditory sensory memory in parents of affected children. We conclude by reviewing possible explanations for the observed group effects.

Background: Some individuals with autism spectrum disorders (ASD) experience linguistic difficulties similar to those found in individuals with specific language impairment (SLI). Whether these behaviours are indicative of a common underlying genetic cause or a superficial similarity is unclear. Methods: Standardised language assessments were administered to three participant groups: parents of children with ASD (Par-A), parents of children with specific language/literacy impairment (Par-L) and parents of typically developing children (Par-T) (n = 30, in each group). Additionally, the Autism-Spectrum Quotient (AQ) was used to assess autism-like tendencies, in particular, social language use. Results: The Par-A group performed better than the Par-L group (and identical to the Par-T group) on all language tests. Conversely, the Par-A group was characterised by higher levels of pragmatic difficulties than the other two groups, as measured by the communication subscale of the AQ. Conclusions: No evidence was found for a shared phenotype in parents of children with ASD and SLI. A model is presented describing the relation between SLI and ASD.

This paper reports on increases in the phonetic inventories of nine children in the fifth and sixth years of experience with cochlear implants. Thirty-six of 44 phones in Australian English reached criterion levels, resulting in intelligible, but not completely natural, speech. The rate of improvement in the sixth year was slow, indicating a probable plateau in performance. (Contains references.) (Author/DB)

Eighty-seven primary-school children with impaired hearing were evaluated using speech perception, production, and language measures over a 3-year period. Forty-seven children with a mean unaided pure-tone-average hearing loss of 106 [...]

Increases in the phonetic inventories of a group of 9 children in the fifth and sixth years of experience with a cochlear implant are reported, extending a previous 4-year study (T. A. Serry & P. J. Blamey, 1999). Thirty-six out of 44 phones in Australian English reached the criterion of 50% correct in the conversational samples of 5 or more children. This level of performance corresponds to intelligible, but not completely natural, speech. The rate of improvement in the sixth year was slow, indicating a probable plateau in performance. The 8 phones that did not attain the 50% criterion in 5 or more children were /IC, [Omega]e, ??, t, s, z, t[integral], [Theta]/. Potential reasons for the slow development or nondevelopment of these phones include very low frequency of occurrence for /IC, [Omega]e, ??/ and the perceptual and articulatory characteristics of /t, s, z, t[integral], [Theta]/. /t/ is also subject to a high degree of allophonic variation in the fluent speech of normally hearing speakers, probably accounting for much of the variability in its articulation in the conversational samples. KEY WORDS: phonetic inventory, hearing-impaired, cochlear prosthesis, children, speech, Historically, the development and maintenance of intelligible speech has been a considerable challenge for children and adults with profound hearing loss (e.g., Hudgins & Numbers, 1942; Markides, 1970). Osberger and [...]

Efficient auditory processing is hypothesized to support language and literacy development. However, behavioral tasks used to assess this hypothesis need to be robust to non-auditory specific individual differences. This study compared frequency discrimination abilities in a heterogeneous sample of adults using two different psychoacoustic task designs, referred to here as: 2I_6A_X and 3I_2AFC designs. The role of individual differences in nonverbal IQ (NVIQ), socioeconomic status (SES) and musical experience in predicting frequency discrimination thresholds on each task were assessed using multiple regression analyses. The 2I_6A_X task was more cognitively demanding and hence more susceptible to differences specifically in SES and musical training. Performance on this task did not, however, relate to nonword repetition ability (a measure of language learning capacity). The 3I_2AFC task, by contrast, was only susceptible to musical training. Moreover, thresholds measured using it predicted some variance in nonword repetition performance. This design thus seems suitable for use in studies addressing questions regarding the role of auditory processing in supporting language and literacy development. [ABSTRACT FROM AUTHOR]

Behavioural and electrophysiological studies give differing impressions of when auditory discrimination is mature. Ability to discriminate frequency and speech contrasts reaches adult levels only around 12 years of age, yet an electrophysiological index of auditory discrimination, the mismatch negativity (MMN), is reported to be as large in children as in adults. Auditory ERPs were measured in 30 children (7 to 12 years), 23 teenagers (13 to 16 years) and 32 adults (35 to 56 years) in an oddball paradigm with tone or syllable stimuli. For each stimulus type, a standard stimulus (1000 Hz tone or syllable [ba]) occurred on 70% of trials, and one of two deviants (1030 or 1200 Hz tone, or syllables [da] or [bi]) equiprobably on the remaining trials. For the traditional MMN interval of 100-250 ms post-onset, size of mismatch responses increased with age, whereas the opposite trend was seen for an interval from 300 to 550 ms post-onset, corresponding to the late discriminative negativity (LDN). Time-frequency analysis of single trials revealed that the MMN resulted from phase-synchronization of oscillations in the theta (4-7 Hz) range, with greater synchronization in adults than children. Furthermore, the amount of synchronization was significantly correlated with frequency discrimination threshold. These results show that neurophysiological processes underlying auditory discrimination continue to develop through childhood and adolescence. Previous reports of adult-like MMN amplitudes in children may be artefactual results of using peak measurements when comparing groups that differ in variance. [ABSTRACT FROM AUTHOR]

Poor discrimination of nonlinguistic sounds has been implicated in language-learning problems in children, but research evidence has been inconsistent. This study included 32 participants with specific language impairment (SLI) and 32 typically developing controls aged 7-16 years. Frequency discrimination thresholds were estimated in a task where participants had to distinguish a higher-frequency tone from a 1000 Hz tone. Neurophysiological responses were assessed in an oddball paradigm. Stimuli were either 1030 or 1200 Hz pure tones (deviants) presented in a series of standard 1000 Hz tones, or syllables (deviant [da] or [bi] in a series of standard /ba/). On the behavioral task, children (7- to 11-year-olds) had high thresholds, regardless of language status, but teenagers (12-16 years) with SLI had higher thresholds than their controls. Conventional analysis of electrophysiological responses showed no difference between groups for the mismatch negativity (MMN), but the late discriminative negativity (LDN) was reduced in amplitude for smaller deviants in participants with SLI. Time-frequency analysis revealed that, whereas the MMN reflected enhanced intertrial coherence in the theta frequency band, the LDN corresponded to a period of event-related desynchronization extending across a wide low-frequency band including delta, theta, and alpha. This manifested as a drop in power in those frequencies, which was marked in the controls but reduced or absent in children with SLI across all stimulus types. This provides compelling evidence for a low-level auditory perceptual impairment in SLI that affects a processing stage after initial detection of a sound change. [ABSTRACT FROM AUTHOR]