Purpose: The purpose of this study was to determine whether individuals with right hemisphere damage (RHD) process impliciture sentences differently from matched controls. The research questions were: (a) Are participants with RHD less accurate than healthy controls in impliciture sentence processing? (b) Does the introduction of story context affect impliciture processing in participants with RHD? (c) Do participants with RHD demonstrate response time profiles that differ from controls?Method: Seven participants with RHD and 16 matched controls participated in two experiments. In Experiment 1, participants listened to 144 impliciture sentences, and verbally responded with the interpretation they thought best fit what the sentence meant. In Experiment 2, participants listened to 100 stories and verbally responded with their interpretation of what the final impliciture sentence meant. There were two story types for each sentence: one that facilitated the normally preferred interpretation, and one that negated that interpretation.Results: For Experiment 1, three participants were less accurate in impliciture comprehension when compared to controls. The results were significant for lexical, possessive, quantitative, and temporal implicitures. For Experiment 2, three participants demonstrated increased accuracy with context. The results were significant for hyperbole, possessive, quantitative, and temporal implicitures. However, item analysis showed that each participant with RHD had difficulty negating the preferred interpretation of the impliciture. For the response time analysis, the control group was significantly slower in the negating compared to the facilitating context condition (F<N>profile). In contrast, participants with RHD did not demonstrate a difference (F=N profile).Conclusions: These findings suggest that reduced accuracy in impliciture processing occurs in some individuals with RHD, although additional research is needed to determine what characteristics are related to poor impliciture comprehension. Participants also were unable to use story contexts as effectively as the control group, showing difficulty negating the normally-preferred interpretation. Because response time profiles differed between participants with RHD and the control group, it is likely that the integrity of the right hemisphere is required for normal processing of impliciture and use of contextual cues. The results suggest a number of additional avenues of research in both the normally aging and RHD populations.

This research was guided by a theoretical framework positing that children with typical language apply general cognitive resources, such as attention, to facilitate language acquisition, and limitations in these processes may contribute to poor language skills. From this perspective, studying the attentional functioning of children who exhibit difficulty with language would have value for both informing this theory and understanding the nature of the disorder. However, research on the attention of children with specific language impairment (SLI) is limited, as only a few subdomains have been addressed to date. In addition, although school-age children with SLI have been studied, the assessment of attentional functioning in preschool children with this disorder has been minimal. This is likely the result the limitations inherent to the methods used for evaluating attentional skills at younger ages. The purpose of this research was to extend a method previously used successfully with preschool children to study selected aspects of attentional control including susceptibility to distraction, inhibitory control, and updating skills. The research questions were: (a) Do children with SLI exhibit increased susceptibility to distraction relative to their typically-developing peers, and if so, does it vary according to the type of distracter (visual, nonverbal-auditory, linguistic) presented? (b) Do children with SLI exhibit poor inhibitory control relative to their typically-developing peers? (c) Do children with SLI and their typically-developing peers display evidence of updating? Thirty-one preschool children with SLI and 31 controls participated in two computer tasks designed to assess these mechanisms of attentional control. The susceptibility to distraction task involved resisting distracters presented in different stimulus modalities (visual and auditory-linguistic/nonlinguistic). Inhibition and updating skills were assessed using a stop signal paradigm. In comparison to typically-developing children, the children with SLI exhibited increased susceptibility to distraction and poor inhibitory control. Unlike the controls, they exhibited no evidence of updating. The results of this investigation will contribute to a long-term goal of addressing how attention may affect language acquisition in children with SLI. In addition, the successful methodology employed in this study may offer an improved procedure for diagnosing attentional difficulties at an early age, regardless of language status.

A common recommendation for communication partners of people with hearing loss is to speak clearly, but how effective is this simple instruction? Does everyone produce clear speech using the same strategies? Is clear speech produced when given minimal instruction the same as that produced when competing background noise is present? The present study examined the acoustic characteristics of passage level speech produced in four different conditions. Twelve talkers (8 female, 4 male) with a mean age of 21 years were audio recorded reading three paragraph length passages. In the first condition talkers read each passage conversationally as though speaking to a friend. In the three experimental conditions, talkers were instructed to speak as clearly as they could, speak as clearly as they could in the presence of multitalker babble, and speak as clearly as they could in the presence of speech-shaped noise. The babble and noise were presented over headphones at a level of 75 dB SPL. Acoustic measures examined changes in rate, frequency, and intensity across condition. Results of this study help clarify what changes talkers make in response to instructions to speak clearly compared to conditions with competing background noise.

Studies of speech perception indicate that it is more difficult for people with and without hearing loss to detect speech in noise. Functional communication in noise, however, has been less often studied; there is currently no well-designed measure of communication effectiveness. The Diapix Task (Baker & Hazan, 2011) has potential; it elicits dialogue by having two people converse to find differences between two pictures. The purpose of the present study was to develop a reliable measure of communication effectiveness and use this measure to determine how noise influences communication. Experiment 1 investigated use of the Diapix Task as a measure of communication effectiveness in noise. Seven young adults with normal hearing, paired with an assistant, completed the Task with three different picture pairs in a sound field of cafeteria noise. Communication effectiveness was measured by counting communication breakdowns. Results indicated that the Task did elicit breakdowns and, out of nine picture pairs, one elicited a different amount of breakdowns than the others; this pair was excluded. Experiment 2 used the Diapix Task to measure communication effectiveness in quiet and different types of noise. Relation between self-reported use of communication strategies and communication effectiveness was also explored. Fourteen young adults with normal hearing completed the Diapix Task with an assistant in three conditions: quiet, cafeteria noise, and competing dialogue. Results indicated that significantly more breakdowns occurred in noise than quiet, but that there was no significant difference between types of noise. Additionally, self-reported use of communication strategies did not correlate with communication effectiveness. Results support use of the Diapix Task as a functional measure of communication effectiveness in young adults with normal hearing; future research should investigate use of the Diapix Task to measure communication effectiveness in clinical populations.

The brain's neural responses to words of different frequencies provide information on lexical organization and the cognitive processes involved in word identification and retrieval of meaning. Monolingual research has shown that exposure to high frequency words yields less cognitive difficulty than low frequency words as demonstrated by smaller N400 waves within even-related potential (ERP) methodology. The purpose of the present study was to compare frequency effects in adult native (L1) and non-native (L2) speakers of English during a sentence reading task embedded with high and low frequency word-pairs. Both L1 and L2 groups produced N400 waves of larger amplitudes for high frequency words compared to low frequency words that peaked around the 400 ms time mark. Group comparison found no significant difference in N400 wave amplitude and peak latency between both groups. The results are discussed with respect to theories of L2 word learning and lexical organization.

One of the fundamental challenges for communication by speech is the variability in speech production/acoustics. Talkers vary in the size and shape of their vocal tract, in dialect, and in speaking mannerisms. These differences all impact the acoustic output. Despite this lack of invariance in the acoustic signal, listeners can correctly perceive the speech of many different talkers. This ability to adapt one's perception to the particular acoustic structure of a talker has been investigated for over fifty years. The prevailing explanation for this phenomenon is that listeners construct talker-specific representations that can serve as referents for subsequent speech sounds. Specifically, it is thought that listeners may either be creating mappings between acoustics and phonemes or extracting the vocal tract anatomy and shape for each individual talker. This research focuses on an alternative explanation. A separate line of work has demonstrated that much of the variance between talkers' productions can be captured in their neutral vocal tract shape (that is, the average shape of their vocal tract across multiple vowel productions). The current model tested is that listeners compute an average spectrum (long term average spectrum - LTAS) of a talker's speech and use it as a referent. If this LTAS resembles the acoustic output of the neutral vocal tract shape - the neutral vowel - then it could accommodate some of the talker based variability. The LTAS model results in four main hypotheses: 1) during carrier phrases, listeners compute an LTAS for the talker; 2) this LTAS resembles the spectrum of the neutral vowel; 3) listeners represent subsequent targets relative to this LTAS referent; 4) such a representation reduces talker-specific acoustic variability. The goal of this project was to further develop and test the predictions arising from these hypotheses. Results suggest that the LTAS model needs to be further investigated, as the simple model proposed does not explain the effects found across all studies.

Dosage has been identified as important element of intervention that has the potential to affect intervention efficacy. The purpose of this study was to examine the role of dose schedule for treatment of grammatical morphology deficits in children with Specific Language Impairment (SLI). Sixteen 4-5 year old children with SLI participated in a 6-week intervention program during which children received equivalent daily Enhanced Conversational Recast treatment targeting grammatical morpheme errors. Half of the children received treatment in one 30-minute session (massed condition). The other half received treatment in three 10-minutes sessions (spaced condition) over a 3-hour period. Progress was assessed three times weekly by probing a child’s use of his/her treatment morpheme and untreated morpheme (a maturational control) in untreated contexts. Pre-to-post treatment morpheme usage differed significantly for children regardless of dosage condition, demonstrating overall treatment efficacy. There were no differences in treatment effects for the massed and spaced conditions. In addition, nonverbal IQ and receptive vocabulary test scores correlated with treatment effect sizes. The study adds to evidence that Enhanced Conversational Recast can produce positive results, in a relatively short period of time, for children with specific language impairment. Moreover, it appears that clinicians may have some flexibility in terms of the dose schedule they employ to deliver this treatment in an evidence-based manner.

Language recovery was examined in 108 individuals with aphasia in the chronic phase of recovery who participated in various forms of aphasia treatment over extended periods of time. The Western Aphasia Battery (WAB) was administered at multiple time points and Aphasia Quotient (AQ) scores were used as a measure of language performance over time. As a group, the cohort showed an improvement of +6.52 AQ points, yielding an average rate of change of +4.07 AQ points per year. The rate of change was greatest at earlier times post onset (between three months and two years), and improvement was greatest for individuals with aphasia in the moderate severity range. Age, sex, and fluency did not have a significant effect on recovery. Education level had marginal predictive value in the direction of those with less education showing greater rate of improvement. These results suggest that language recovery continues during the chronic stage for individuals who are involved in some form of rehabilitation activity, especially in individuals with aphasia of moderate severity.

One of the lasting concerns in audiology is the unexplained individual differences in speech perception performance even for individuals with similar audiograms. One proposal is that there are cognitive/perceptual individual differences underlying this vulnerability and that these differences are present in normal hearing (NH) individuals but do not reveal themselves in studies that use clear speech produced in quiet (because of a ceiling effect). However, previous studies have failed to uncover cognitive/perceptual variables that explain much of the variance in NH performance on more challenging degraded speech tasks. This lack of strong correlations may be due to either examining the wrong measures (e.g., working memory capacity) or to there being no reliable differences in degraded speech performance in NH listeners (i.e., variability in performance is due to measurement noise). The proposed project has 3 aims; the first, is to establish whether there are reliable individual differences in degraded speech performance for NH listeners that are sustained both across degradation types (speech in noise, compressed speech, noise-vocoded speech) and across multiple testing sessions. The second aim is to establish whether there are reliable differences in NH listeners' ability to adapt their phonetic categories based on short-term statistics both across tasks and across sessions; and finally, to determine whether performance on degraded speech perception tasks are correlated with performance on phonetic adaptability tasks, thus establishing a possible explanatory variable for individual differences in speech perception for NH and hearing impaired listeners.

Purpose: To identify effects of variability of visual input on development of conceptual representations of academic concepts for students with normal language (NL) and language-learning disabilities (LLD). Method: Students with NL (n=38) and LLD (n=11) participated in a computer-based training for introductory biology course concepts. Participants were trained on half the concepts under a low-variability condition and half under a high-variability condition. Participants completed a post-test in which they were asked to identify and rate the accuracy of novel and trained visual representations of the concepts. We performed separate repeated measures ANOVAs to examine the accuracy of identification and ratings. Results: Participants were equally accurate on trained and novel items in the high-variability condition, but were less accurate on novel items only in the low-variability condition. The LLD group showed the same pattern as the NL group; they were just less accurate. Conclusions: Results indicated that high-variability visual input may facilitate the acquisition of academic concepts in both NL and LLD college students. Specifically, it may be beneficial for generalization to novel representations of concepts. Implicit learning methods may be harnessed by college courses to provide students with basic conceptual knowledge when entering courses or beginning new units.