Dissertation Abstracts

Neurophysiological bases of frequency discrimination in children with auditory processing disorder or specific language impairment

Author: Rota-Donahue, Christine

The purpose of this study was to determine if 10-12 year old children with Auditory Processing Disorder (APD) or Specific Language Impairment (SLI) could discriminate three different frequency changes behaviorally and electrophysiologically. Behavioral frequency discrimination and event-related potentials were examined using a 1000Hz pure tone base frequency. Typically developing children and children with APD or SLI differed in in their detection of frequency changes: behavioral results were below chance level and the MMN amplitude was smaller in the impaired population. Slight differences between children with APD and children with SLI were also found that might shed light on the controversy regarding the deficits underlying pediatric APD, either a disorder in itself, or a symptom of a higher information processing deficit.

Word association and semantic priming in individuals with autism spectrum disorders

Author: Battaglia, Dana

Lexical organization in individuals with Autism Spectrum Disorders (ASD) is not fully understood. This study investigated the nature of word association in individuals with ASD using two experimental paradigms: a word association task (Experiment 1), followed by an individualized semantic priming task (Experiment 2). In Experiment 1, participants were asked to name as many semantically related words as possible when auditorily presented with a target (e.g., participants heard the word cat and were asked to name semantically related words, within 60 seconds). In Experiment 2, participants were asked to name a target picture, preceded in time by 50 ms. Four types of auditory primes were used: Associated (e.g., bird-nest), Individual Semantic (e.g., bird-(tree)), Identity (e.g., bird-bird), and Unrelated (e.g., bird-car). The primes in the Individual Semantic condition were semantic associates obtained from responses in Experiment 1. Participants were 15 individuals with ASD (aged 14;0 to 19;2), 16 with typical language development matched for chronological age (CAM) (aged 15;0 to 19;7), and 14 with typical language development matched for raw score (VM) on the Peabody Picture Vocabulary Test 4 th ed (aged 8;1 to 13;4) (Dunn & Dunn, 2007). In Experiment 1, while individuals with ASD produced many appropriate word associations, they also produced more unrelated word associations than both control groups. In Experiment 2, participants’ reaction times revealed that individuals with ASD performed similarly to both control groups in all conditions: they exhibited priming in the Identity condition, but not in the Associated and Individual Semantic conditions. Absence of group x condition interaction in the Associated condition calls method into question. Results from Experiment 1 suggest that individuals with ASD have a similarly organized lexicon (i.e., more associated than unrelated responses to a given target), but the breadth and depth of their lexicons may be immature (i.e., higher proportion of unrelated responses, relative to both control groups). Findings have clinical and educational implications for vocabulary instruction in individuals with ASD. Word associations may first appear to be typical. However, in-depth analyses (i.e., monitoring associated, perseveration, proper noun, phrase, or unrelated responses), provides robust information regarding lexical organization.

Auditory selective attention and language processing in children with and without specific language impairment

Author: Victorino, Kristen Russo


There is a growing consensus that children with specific language impairment (SLI) have impairments in basic cognitive functions that underlie linguistic performance deficits. One such function is attention and its control. Selective attention involves the cognitive control of attention directed towards a relevant stimulus and a simultaneous inhibition of attention towards irrelevant stimuli.

In this study, a novel paradigm was used to gain information about the way children with typical language development (TLD) and with SLI attend to and process linguistic stimuli. Participants listened to words through headphones and were instructed to attend to the words in one ear while ignoring the words in the other ear. They were simultaneously presented with pictures and asked to make a lexical (same/different) decision. The pictures either matched the attended word, the unattended word, or were unrelated. A baseline condition utilized the cross-modal decision task in the absence of distracters. The groups performed with similar accuracy. Analysis of reaction time (RT) revealed main effects for Group and Condition. Analysis of patterns of performance within groups indicated that increasing levels of interference resulted in slower RTs for the TLD group. These data suggest that subjects with TLD actively inhibited competing stimuli in the unattended channel and selected the relevant stimuli efficiently. Subjects with SLI performed with a different pattern; they did not process competing stimuli differently from non-competing stimuli in the unattended channel. These results suggest that subjects with SLI had difficulty inhibiting distractors of all types. Analysis of supplemental task performance revealed deficits in the SLI group on tasks of verbal working memory and visuo-spatial executive function, but no group differences in basic dichotic listening skills. Correlations between experimental task performance, language scores, nonverbal intelligence scores, and supplemental task scores were examined. Moderate correlations between performance on the auditory selective attention task and the working memory task, as well as on the nonverbal intelligence measure, suggested that a common construct contributed to performance on these measures. However, regression analyses revealed that these factors did not adequately account for the variance in experimental RTs, suggesting that additional, unidentified factors were also at play.

An electrophysiological and behavioral examination of cognitive control in children with specific language impairment

Author: Tropper, Baila


There is accumulating evidence that children with specific language impairment (SLI) are deficient in managing internal, cognitive conflict that arises as they process information (e.g., Bishop & Norbury, 2005). This ability is referred to as cognitive control , a higher-order skill that encompasses the detection and resolution of conflict among competing response alternatives (Miller & Cohen, 2001). A deficit in cognitive control would likely have wide-ranging ramifications for the efficiency of language and non-language processing and might underlie poor information processing in the SLI population. The goal of the present investigation was to examine whether children with SLI are deficient in managing conflict between competing response tendencies that are invoked during processing of linguistic and non-linguistic stimuli. A behavioral method involving a GO/No-GO paradigm was employed simultaneously with the collection of event-related potentials (ERP). The N2 component was utilized as a neural index of the ability to detect conflict between the tendencies to make a speeded response (GO) and to refrain from responding (No-GO).

Behavioral measures of hit rates and false-alarm rates in response to linguistic and non-linguistic stimuli did not distinguish children with SLI from children with typical language development of the same age (TLD-A). By contrast, analysis of the N2 component revealed absent, or attenuated, and delayed divergence of GO and No-GO amplitudes in SLI relative to TLD-A children in response to linguistic stimuli presented at various probability levels. The N2 effect in children with SLI resembled that of children with typical language development who were on average three years younger. This finding suggests that school-age children with SLI exhibit a maturational lag in detecting conflict among competing response alternatives when processing linguistic information. Deficient conflict detection may, in turn, hinder SLI children’s ability to resolve conflict among semantic representations that are activated during language processing. An understanding of this limitation in cognitive control elucidates information processing deficits in SLI and bears promise to enhance our knowledge of how to remediate this developmental disorder.