Children's auditory lexical decisions: a limited processing capacity account of language impairment

Developmental Language Disorder Is Associated With Slower Processing Across Domains: A Meta-Analysis of Time-Based Tasks

PURPOSE

Individuals with developmental language disorder (DLD) often exhibit slower processing on time-based tasks in comparison with age-matched peers. Processing speed has been linked to various linguistic skills and might serve as a global indicator of individual differences in language abilities. Despite an extensive literature on processing speed in DLD, it remains unclear whether slower processing is domain general or restricted to linguistic and/or auditory tasks.

METHOD

This meta-analysis used robust variance estimation to compare response/reaction times (RTs) of DLD and age-matched groups (N = 812 DLD, 870 neurotypical; M _age [DLD] = 8.9 years, range: 4.3-22.7 years). Moderators included task (simple RT, choice RT, naming, congruent/baseline conditions of interference control tasks), stimulus type (linguistic/nonlinguistic), stimulus modality (auditory/nonauditory), and response modality (verbal/nonverbal). Age and publication year were covariates.

RESULTS

The overall effect based on 46 studies and 144 estimates indicated longer mean RTs in DLD groups (g = .47, p < .001, 95% CI [.38, .55]). Moderator analyses indicated larger effects when tasks required verbal as opposed to nonverbal responses. No other moderators approached significance. All subgroup analyses were significant, indicating longer mean RTs in DLD groups across tasks, stimulus types, stimulus modalities, and response modalities.

CONCLUSIONS

Individuals with DLD exhibit longer RTs across verbal and nonverbal tasks, which may contribute to observed difficulties in language, motor skills, and executive functioning. Simple processing speed measures should be included in screening for language delays but may not be suitable for differential diagnosis, given that slower processing may occur across multiple disorders.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21809355.

Word Form Processing in Primary School Children: A Psycholinguistic Perspective

Purpose From a psycholinguistic perspective, the quality of the stored word form in the phonological input lexicon, as well as its effective retrieval from the phonological output lexicon, is of great importance in lexical processing. This study aimed at gaining a deeper understanding of (a)typical word form processing in primary school children. In particular, age-related development and profiles of word form processing including children's response behavior were investigated. Method A sample of 164 monolingual primary school children (6-9 years of age) was tested in a cross-sectional design using two word form-related tasks (auditory lexical decision and rapid naming) with carefully controlled stimuli in combination with traditional vocabulary tests and a nonword repetition task. Results First, an age-related improvement (better performance and acceleration of reaction times) was found for both word form-related tasks. Second, a cluster analysis revealed five clusters with different profiles of word processing. Beside a cluster with overall results of above average, we found two clusters including children with typical lexical abilities who applied specific strategies to deal with the tasks (speed-accuracy trade-offs). Two other clusters represented weak lexical abilities at different levels of word processing. Conclusions Children's abilities in word form processing develop over time and are characterized by developmental boosts that occur at different times in development. The uncovered profiles document patterns of (a)typical lexical processing. Since difficulties with word form processing are easily overlooked in clinical assessment, lexical decision and rapid naming tasks offer valuable tools for an in-depth evaluation of lexical skills. Supplemental Material https://doi.org/10.23641/asha.12986036.

Auditory attention in individuals with tinnitus

Introduction

Tinnitus is characterized by the presence of a sound in the absence of external sound stimulus. In individuals with normal audiometry, it may be associated with auditory attention difficulty, especially in those who report high tinnitus annoyance.

Objective

To investigate auditory attention ability in individuals with tinnitus complaint.

Methods

Cross-sectional analytical observational study. We evaluated 30 volunteers with normal hearing (up to 25 dBHL): 15 with tinnitus (test group) and 15 with no complaints (control group), aged between 18-40 years. The volunteers answered the tinnitus handicap inventory questionnaire and a visual analogue scale. Subsequently, a basic audiological evaluation (meatoscopy, tonal and vocal audiometry, and imittanciometry) and psychoacoustic measures of tinnitus (loudness and pitch) were performed. To evaluate auditory attention, the following tests were performed: auditory cognitive evoked potential (P300), central auditory processing tests (dichotic digits test and speech-in-noise test) and sustained auditory attention ability test.

Results

In the tinnitus handicap inventory, individuals with tinnitus had a mean score of 37.78 (±27.05), characterized as moderate degree. In the dichotic digits test (binaural separation), a difference was observed between the groups in both ears. Moreover, there was a difference in the speech-in-noise test in both ears (RE: p = 0.044; LE: p = 0.019), in P300 (p = 0.049) and in total sustained auditory attention ability test (p = 0.032). Also, there is a negative correlation between sustained auditory attention ability test, decrease in attentiveness and binaural integration (RE: p = 0.044; LE: p = 0.048).

Conclusions

Individuals with tinnitus had a poorer performance compared to the control group regarding auditory attention ability. Therefore, it is inferred that tinnitus is associated with poor performance in selective and sustained auditory attention in the assessed volunteers. These aspects should be considered for the management of patients with tinnitus.

Auditory Lexical Decisions in Developmental Language Disorder: A Meta-Analysis of Behavioral Studies

PURPOSE

Despite the apparent primacy of syntactic deficits, children with developmental language disorder (DLD) often also evidence lexical impairments. In particular, it has been argued that this population have difficulty forming lexical representations that are detailed enough to support effective spoken word processing. In order to better understand this deficit, a meta-analysis of studies testing children with DLD in the auditory lexical decision task was conducted. The objective was to provide summary effect size estimates for accuracy and response time measures for comparisons to age- and language-matched control groups.

METHOD

Two thousand three hundred seventy-two records were initially identified through electronic searches and expert consultation, with this cohort reduced to 9 through duplicate removal and the application of eligibility and quality criteria. The final study cohort included 499 children aged 3;8-11;4 (years;months).

RESULTS

Multivariate analysis suggests that children with DLD were significantly less accurate in the auditory lexical decision task than age-matched controls. For the response time estimate, however, confidence intervals for the same group comparison crossed 0, suggesting no reliable difference between groups. Confidence intervals also crossed 0 for language-matched control estimates for both accuracy and response time, suggesting no reliable difference between groups on either measure.

CONCLUSION

Results broadly support the hypothesis that children with DLD have difficulty in forming detailed lexical representations relative to age- though not language-matched peers. However, further work is required to determine the performance profiles of potential subgroups and the impact of manipulating different lexical characteristics, such as the position and degree of nonword error, phonotactic probability, and semantic network size.

Novel Morpheme Learning in Monolingual and Bilingual Children

PURPOSE

The purpose of the present study was to examine the utility of a novel morpheme learning task for indexing typical language abilities in children characterized by diverse language backgrounds.

METHOD

Three groups of 5- to 6-year-old children were tested: monolingual speakers of English, native speakers of Spanish who also spoke English (Spanish-L1 bilinguals), and native speakers of English who also spoke Spanish (English-L1 bilinguals). All children were taught a new derivational morpheme /ku/ marking part-whole distinction in conjunction with English nouns. Retention was measured via a receptive task, and sensitivity and reaction time (RT) data were collected.

RESULTS

All three groups of children learned the novel morpheme successfully and were able to generalize its use to untaught nouns. Furthermore, language characteristics (degree of exposure and levels of performance on standardized measures) did not contribute to bilingual children's learning outcomes.

CONCLUSION

Together, the findings indicate that this particular version of the novel morpheme learning task may be resistant to influences associated with language background and suggest potential usefulness of the task to clinical practice.

Lexical conflict resolution in children with specific language impairment

The aim of our study is to examine the effect of conflict on naming latencies in children with specific language impairment (SLI) and typically developing (TD) children and to explore whether deficits in conflict resolution contribute to lexical problems in SLI. In light of previous results showing difficulties with inhibitory functions in SLI, we expected higher semantic conflict effect in the SLI than in the TD group. To investigate this question 13 children with SLI and 13 age- and gender-matched TD children performed a picture naming task in which the level of conflict was manipulated and naming latencies were measured. Children took longer to name pictures in high conflict conditions than in low conflict conditions. This effect was equally present in the SLI and TD groups. Our results suggest that word production is more effortful for children when conflict resolution is required but children with SLI manage competing lexical representations as efficiently as TD children. This result contradicts studies, which found difficulties with inhibitory functions and is in line with findings of intact inhibitory abilities in children with SLI. Further studies should rule out the possibility that in SLI lower level of conflict resulting from weaker lexical representations masks impairments in inhibition, and investigate the effect of linguistic conflict in other areas.

Differences in the performance of children with specific language impairment and their typically developing peers on nonverbal cognitive tests: a meta-analysis

PURPOSE

This study used meta-analysis to investigate the difference in nonverbal cognitive test performance of children with specific language impairment (SLI) and their typically developing (TD) peers.

METHOD

The meta-analysis included studies (a) that were published between 1995 and 2012 of children with SLI who were age matched (and not nonverbal cognitive matched) to TD peers and given a norm-referenced nonverbal cognitive test and (b) that reported sufficient data for an effect size analysis. Multilevel modeling was used to examine the performance of children with SLI relative to their typically developing, age-matched peers on nonverbal IQ tests.

RESULTS

Across 138 samples from 131 studies, on average children with SLI scored 0.69 standard deviations below their TD peers on nonverbal cognitive tests after adjusting for the differences in the tests used, the low-boundary cutoff scores, the age of the participants, and whether studies matched the two groups on socioeconomic status.

DISCUSSION

The lower performance of children with SLI relative to TD children on nonverbal IQ tests has theoretical implications for the characterization of SLI and clinical and political implications regarding how nonverbal cognitive tests are used and interpreted for children with this disorder.

Lexical activation during sentence comprehension in adolescents with history of Specific Language Impairment

One remarkable characteristic of speech comprehension in typically developing (TD) children and adults is the speed with which the listener can integrate information across multiple lexical items to anticipate upcoming referents. Although children with Specific Language Impairment (SLI) show lexical deficits (Sheng & McGregor, 2010) and slower speed of processing (Leonard et al., 2007), relatively little is known about how these deficits manifest in real-time sentence comprehension. In this study, we examine lexical activation in the comprehension of simple transitive sentences in adolescents with a history of SLI and age-matched, TD peers. Participants listened to sentences that consisted of the form, Article-Agent-Action-Article-Theme, (e.g., The pirate chases the ship) while viewing pictures of four objects that varied in their relationship to the Agent and Action of the sentence (e.g., Target, Agent-Related, Action-Related, and Unrelated). Adolescents with SLI were as fast as their TD peers to fixate on the sentence's final item (the Target) but differed in their post-action onset visual fixations to the Action-Related item. Additional exploratory analyses of the spatial distribution of their visual fixations revealed that the SLI group had a qualitatively different pattern of fixations to object images than did the control group. The findings indicate that adolescents with SLI integrate lexical information across words to anticipate likely or expected meanings with the same relative fluency and speed as do their TD peers. However, the failure of the SLI group to show increased fixations to Action-Related items after the onset of the action suggests lexical integration deficits that result in failure to consider alternate sentence interpretations.

LEARNING OUTCOMES

As a result of this paper, the reader will be able to describe several benefits of using eye-tracking methods to study populations with language disorders. They should also recognize several potential explanations for lexical deficits in SLI, including possible reduced speed of processing, and degraded lexical representations. Finally, they should recall the main outcomes of this study, including that adolescents with SLI show different timing and location of eye-fixations while interpreting sentences than their age-matched peers.

The acquisition of prosodic constraints on derivational morphology in typically developing children and children with SLI

Aim of this study was to investigate at what age German children master prosodic and morphological constraints in the acquisition of the word formation paradigm -heit/-keit, which is comparable to English -ness, and whether children with Specific Language Impairment (SLI) have difficulties identifying the prosodic cues from the input. Derived words with -heit contain simple bases with final stress and those with -keit have complex bases with a weak final syllable. Three groups of typically developing children (four, six and eight years old) and 18 children with SLI (from 8 to 10 years) had to produce either -heit or -keit derivations in a sentence completion task. The results show that typically developing children mastered these derivations by the age of six only when both prosodic and morphological cues were present, while eight-year-old children performed almost adult-like. In contrast, most children with SLI did not produce systematic responses that follow prosodic and/or morphological constraints. The findings support the assumption that children with SLI are less sensitive to prosodic properties of grammatical forms than typically developing peers.

Interpretation of compound nouns by adolescents with specific language impairment and autism spectrum disorders: an investigation of phenotypic overlap

The study aimed to investigate (i) whether adolescents with Specific Language Impairment (SLI) and Autism plus Language Impairment (ALI) experience word-formation difficulties, and (ii) whether these two groups present with a similar language phenotype. The study investigated four groups using a 2 (language status) ×2 (autism status) design; adolescents with SLI (n = 14), ALI (n = 16), Autism Language-Typical (ALT; n = 14), and language matched controls (n = 17), with all groups presenting with typical non-verbal skills. Mean age was 14;10. Comprehension of conventional Noun-Noun lexical compounds (e.g., snowman), synthetic compounds (SCs, e.g., cat chaser), and novel root compounds (RCs, e.g., sheep socks), was assessed using a forced-choice picture selection task. The SLI and ALI participants frequently mis-parsed the SCs, interpreting the first noun as the agent. Those with poorer vocabularies and non-word repetition had greater difficulties. Reaction time (RT) profiles were flatter in the ASD groups, with similar RTs across different compounds. Language difficulties in the SLI and ALI groups extend to word-formation processes; for example, comprehension of SCs. This may reflect difficulties making analogies with stored lexical items. Overall the results support the hypothesis of a phenotypic overlap between SLI and ALI.

Spoken Language Processing Model: Bridging Auditory and Language Processing to Guide Assessment and Intervention

Purpose

This article outlines the author’s conceptualization of the key mechanisms that are engaged in the processing of spoken language, referred to as the spoken language processing model. The act of processing what is heard is very complex and involves the successful intertwining of auditory, cognitive, and language mechanisms. Spoken language processing disorders occur when a breakdown in any of these mechanisms impacts an individual’s ability to effectively process and use the information that is heard. The symptoms vary depending on the underlying deficit(s). The primary purpose of this article is to provide the reader with a basic understanding of these mechanisms, and, in turn, enable readers to (a) review the literature concerning processing disorders with discernment and (b) have a foundation for developing a test battery to derive composite profiles of individuals' processing abilities.

Method

A review of the literature, overview of the spoken language processing model, and suggested approach to diagnostic assessment are presented.

Conclusion

Spoken language processing can break down due to a myriad of underlying causes. Central auditory nervous system deficits can impact not only the initial processing of stimuli but possibly the development of effective language skills. On the other hand, deficits in various cognitive and language mechanisms can similarly impact the auditory processing of speech stimuli. Therefore, it is critical to understand how these mechanisms interact and contribute to the processing of speech stimuli.

Relation of three mechanisms of working memory to children’s complex span performance

There is a paucity of research examining the relative contribution of the different mechanisms of working memory (short-term storage [STM], processing speed) to children’s complex memory span. This study served to replicate and extend the few extant studies that have examined the issue. In this study, the relative contribution of three mechanisms of working memory — STM storage, processing speed, attentional resource allocation — to children’s complex span was examined. Children (6—12) completed a digit span task, an auditory-visual reaction time task, a task of attentional allocation, and a complex (listening) span task. Correlation analyses revealed that, after controlling for age, storage, processing speed, and attentional allocation significantly correlated with complex span. Regression analyses showed that, after partialling out age, storage accounted for 12.1% of unique variance in complex span and processing speed accounted for another 6.6% of unique variance; allocation contributed no unique variance. Consistent with the developmental literature, storage and general processing speed play critical roles in children’s complex span performance.

Role of working memory in typically developing children's complex sentence comprehension

The influence of three mechanisms of working memory (phonological short-term memory (PSTM capacity), attentional resource control/allocation, and processing speed) on children's complex (and simple) sentence comprehension was investigated. Fifty two children (6-12 years) completed a nonword repetition task (indexing PSTM), concurrent verbal processing-storage task (indexing resource control/allocation), auditory-visual reaction time (RT) task (indexing processing speed), and a sentence comprehension task that included complex and simple sentences. Correlation and regression analyses were run to determine the association between the memory variables and sentence comprehension accuracy. Results revealed: (1) none of the memory variables correlated with simple sentence comprehension, (2) resource control/allocation and processing speed correlated significantly with complex sentence comprehension, even after covarying for age, and (3) attentional functioning and processing speed predicted complex sentence comprehension (after accounting for age). Results were interpreted to suggest that working memory is significantly involved in school age children's comprehension of familiar complex sentence structures.

Third graders' metalinguistic skills, reading skills, and stress production in derived English words

PURPOSE

This study examined relationships between 3rd graders' metalinguistic skills (phonological and morphological awareness), reading skills (decoding and word identification), and accurate stress production in derived words with stress-changing suffixes.

METHOD

Seventy-six typically developing 3rd-grade children (M=8;8[years;months]) participated in a battery of tests measuring general oral language ability, phonological and morphological awareness skills, reading skills, and derived word production.

RESULTS

Significant positive correlations between stress accuracy in derived words and all other measures were found. Two multiple regressions were run, one with stress accuracy as the outcome variable and the other with decoding as the outcome variable. Metalinguistic and decoding skills independently accounted for a significant proportion of the variance in derived word stress production beyond that accounted for by age and general oral language ability. When decoding was the outcome variable, accurate stress production explained a significant amount of variance (11%) after phonological and morphological awareness were controlled.

CONCLUSION

The relationship between accurate stress production and decoding appears to be strong and bidirectional. Possibly, the stress accuracy measure taps into another level of phonological awareness (i.e., morphophonological awareness), which develops later than typical segmental measures of phonological awareness.

Examining the language performances of children with and without specific language impairment: contributions of phonological short-term memory and speed of processing

PURPOSE

This study investigated the effects of processing speed and phonological short-term memory (PSTM) on children's language performance.

METHOD

Forty-eight school-age children with specific language impairment (SLI) and age peers completed auditory detection reaction time (RT) and nonword repetition tasks, the Clinical Evaluation of Language Fundamentals-Revised (CELF-R; E. Semel, E. Wiig, & W. Secord, 1987), and a word recognition RT task. Correlation and regression were used to determine unique and shared contributions to variance among measures.

RESULTS

Children with SLI were outperformed by age peers on each task. Auditory detection RT was correlated with nonword repetition (NWR) in each group. However, both variables covaried with age, and auditory detection RT did not contribute unique variance to NWR in either group. For the SLI group, NWR predicted unique variance in CELF-R performance (about 15%); auditory detection RT predicted a smaller amount of unique variance in the word recognition RT task (about 9%).

CONCLUSION

Processing speed and PSTM measures covaried with chronological age. Processing speed was associated with offline language performance only through association with PSTM. Processing speed contributed to online language performance, suggesting that speed is associated with processing more familiar language material (i.e., lexical content and structure) than less familiar material (e.g., various content on the CELF-R).

Derivational morphology in children with grammatical-specific language impairment

Although it is well-established that children with Specific Language Impairment characteristically optionally inflect forms that require tense and agreement marking, their abilities with regards to derivational suffixation are less well understood. In this paper we provide evidence from children with Grammatical-Specific Language Impairment (G-SLI) that derivational suffixes, unlike tense and agreement suffixes, are not omitted in elicitation tasks. We investigate two types of derivation - comparative/superlative formation and adjective-from-noun formation - and reveal that G-SLI children supply these suffixes at high rates, equivalent to their language matched peers. Moreover, increasing the phonological or morphological complexity of the stimulus does not trigger suffix omission, although it results in non-target forms that are not characteristic of typically developing children. We discuss what these results reveal about the nature of the deficit in G-SLI within the context of three hypotheses of SLI: the Extended Optional Infinitive, Implicit Rule and Computational Grammatical Complexity Hypotheses.

Real-time language processing in school-age children with specific language impairment

BACKGROUND

School-age children with specific language impairment (SLI) exhibit slower real-time (i.e. immediate) language processing relative to same-age peers and younger, language-matched peers. Results of the few studies that have been done seem to indicate that the slower language processing of children with SLI is due to inefficient higher-order linguistic processing and not to difficulties with more basic acoustic-phonetic processing. However, this claim requires further experimental verification.

AIMS

It was investigated whether the real-time language processing deficit of children with SLI arises from inferior acoustic-phonetic processing, inefficient linguistic processing, or both poor sensory processing and linguistic processing. If these children's impaired online language processing is due to inferior acoustic-phonetic processing, then their reaction time (RT) for recognizing words presented in list fashion should be significantly longer relative to control children's RT. If, however, their impaired language processing relates to inefficient linguistic processing, then, relative to control children, their RT for word-list-presented words should be comparable and their sentence-embedded word-recognition RT should be significantly longer.

METHODS & PROCEDURES

Sixteen school-age children with SLI, 16 age-matched (CA) typically developing children, and 16 receptive-syntax matched (RS) children completed two word-recognition RT tasks. In one task, children monitored word lists for the occurrence of a target word (isolated lexical processing task). In the second task, children monitored simple sentences for a target word (sentence-embedded lexical processing task). In both tasks, children made a timed response immediately upon recognizing the target.

OUTCOMES & RESULTS

Children with SLI and CA children showed comparable RT in the isolated lexical processing task and both were faster than RS children. In the sentence-processing task, children with SLI were slower at lexical processing than CA and RS children, with CA children demonstrating the fastest processing.

CONCLUSIONS

The real-time language processing of children with SLI appears to be attributable to inefficient higher-order linguistic processing operations and not to inferior acoustic-phonetic processing. The slower language processing of children with SLI relative to younger, language-matched children suggests that the language mechanism of children with SLI operates more slowly than what might otherwise be predicted by their linguistic competence.

School-aged children's phonological production of derived English words

PURPOSE

Little is known about the phonological aspects of derivational processes. Neutral suffixes (e.g., -ness) that do not change stress and rhythmic or nonneutral suffixes (e.g., -ity) that alter stem stress were used in a production task that explored developmental changes in phonological accuracy of derived English words.

METHOD

Three groups of typically achieving children, aged 7 (n = 19), 8 (n = 18), and 9 (n = 15) years, produced derived words in isolation (12 words with rhythmic suffixes and 10 with neutral suffixes). Productions were transcribed from audio-recordings.

RESULTS

Stress accuracy was at ceiling levels for neutral derived words but steadily improved in words with rhythmic suffixes. The predominant stress error was maintaining stem stress in the derived form. Children also made syllabification and consonant errors (in isolation and overlapping with stem stress errors). More errors occurred on derived words with vowel changes than without.

CONCLUSIONS

Morphophonological knowledge for words with rhythmic suffixes undergoes development in early school-aged children. The number or degree of phonological changes between the stem and derived word appears to be an important variable in accurate production.

The nature of written language deficits in children with SLI

Children with specific language impairment (SLI) have associated difficulties in reading decoding and reading comprehension. To date, few research studies have examined the children's written language. The aim of the present study was to (a) evaluate the nature and extent of the children's difficulties with writing and (b) investigate the relationship between oral and written language. Eleven children with SLI were identified (mean age = 11 years) and were compared with a group of children matched for chronological age (CA; mean age = 11;2 [years;months]) and language age (LA; mean CA = 7;3). All groups completed standardized measures of language production, writing, and reading decoding. The writing assessment revealed that the SLI group wrote fewer words and produced proportionately more syntax errors than the CA group, but they did not differ on a measure of content of written language or on the proportion of spelling errors. The SLI group also produced proportionately more syntax errors than the LA group. The relationships among oral language, reading, and writing differed for the 3 groups. The nature and extent of the children's written language problems are considered in the context of difficulties with spoken language.

Present tense be use in young children with specific language impairment: less is more

A well-known characteristic of children with specific language impairment (SLI) is a significant deficit in grammatical morphology production compared with younger, language-matched, typically developing children. This is true for present tense be (am, is, are), as well as other inflectional morphemes. However, grammatical morpheme learning by children with SLI may vary depending on developmental stage. Participants were 8 boys with SLI (42 to 58 months old with mean length of utterances [MLUs] < or = 3.0 morphemes) and 14 MLU-matched controls (girls and boys; mean age of 27 months). These groups were younger and had lower MLUs than groups from oft-cited studies (e.g., Cleave and Rice, 1997; Leonard, Bortolini, Caselli, McGregor, and Sabbadini, 1992; Leonard, Eyer, Bedore, and Grela, 1997; Rice, Wexler, and Hershberger, 1998). The SLI group had a significantly higher percentage of be use in obligatory contexts (46%) than did the younger, typically developing children (27%). This pattern of better performance in grammatical morphology by SLI groups than controls has been reported. Ingram (1972) and Morehead and Ingram (1973) found similar results for children with language impairment in early-MLU stages. Although findings are presented with caution, they afford an opportunity to consider the nature of SLI. If SLI represents a general processing limitation, then that limitation might enable the language learner with SLI to acquire some initial morphological mappings with relative success. This apparent paradox, which also is evident in normal language acquisition, has been termed less is more by Newport (1990). Limited perception and memory force attention to smaller pieces of the input, and these constraints simplify the task for the language learner. SLI is compared with a chronically constrained system that initially assists the learner to achieve basic form-function mappings but ultimately hinders mastery of English morphology.

The search for common ground: Part I. Lexical performance by linguistically diverse learners

This study examines lexical performance by 3 groups of linguistically diverse school-age learners: English-only speakers with primary language impairment (LI), typical English-only speakers (EO), and typical bilingual Spanish-English speakers (BI). The accuracy and response time (RT) of 100 8- to 13-year-old children in word recognition and picture-naming tasks were analyzed. Within each task, stimulus difficulty was manipulated to include very easy stimuli (words that were high frequency/had an early age of acquisition in English) and more difficult stimuli (words of low frequency/late age of acquisition [AOA]). There was no difference among groups in real-word recognition accuracy or RT; all 3 groups showed lower accuracy with low-frequency words. In picture naming, all 3 groups showed a longer RT for words with a late AOA, although AOA had a disproportionate negative impact on BI performance. The EO group was faster and more accurate than both LI and BI groups in conditions with later acquired stimuli. Results are discussed in terms of quantitative differences separating EO children from the other 2 groups and qualitative similarities linking monolingual children with and without LI.

The search for common ground: Part II. Nonlinguistic performance by linguistically diverse learners

Below-average performance on some nonlinguistic tasks often is considered a potential correlate of primary language impairment (LI). If nonlinguistic cognitive processing truly is deficient in children with LI, then measures may be identified that distinguish language learners at risk for LI that are independent of the number and type of languages learned. This study focuses on within- and across-task performance on 4 basic nonlinguistic processing tasks. The aim was to systematically investigate areas of potential overlap and divergence among 3 groups of linguistically diverse children: English-only speakers with LI, typically developing English-only speakers (EO), and typically developing bilingual Spanish-English speakers (BI). The performance of the 100 8-13-year-old children who took part in J. Windsor and K. Kohnert's (2004) study was analyzed. Experimental tasks were simple and choice versions of auditory- and visual-detection tasks. Each task included 4 levels of motor difficulty: responding with the preferred and nonpreferred hand and foot. Analyses revealed no significant differences among groups in simple auditory detection. The EO group was significantly faster than the LI group in each of the other 3 tasks. While the same pattern was evident for the BI group, the difference was significant only in choice visual detection. Overall patterns of response latency within and across tasks were qualitatively similar across the 3 groups. Development, indexed here by chronological age, played a significant role in predicting response latencies for children in all 3 groups.

Listening effort and fatigue in school-age children with and without hearing loss

Parents, audiologists, and educators have long speculated that children with hearing loss must expend more effort and, therefore, fatigue more easily than their peers with normal hearing when listening in adverse acoustic conditions. Until now, however, very few studies have been conducted to substantiate these speculations. Two experiments were conducted with school-age children with mild-to-moderate hearing loss and with normal hearing. In the first experiment, salivary cortisol levels and a self-rating measure were used to measure fatigue. Neither cortisol measurements nor self-rated measures of fatigue revealed significant differences between children with hearing loss and their normal-hearing peers. In the second experiment, however, a dual-task paradigm used to study listening effort indicated that children with hearing loss expend more effort in listening than children with normal hearing. Results are discussed in terms of clinical application and future research needs.

English derivational suffix frequency and children's stress judgments

Considering the importance of word and stem frequency in the adult lexical processing literature, and the effect of input frequency on children's acquisition of words (Tardif, Shatz, and Naigles, 1997), it was hypothesized that children's acquisition of English morphologically conditioned stress alternations would be affected by the frequency with which children were exposed to different stress-changing suffixes (e.g., -tion, -ity, and -ic). Study 1 determined the proportional representation of suffixes in a children's literature corpus, thereby allowing the suffix variable to be established. Study 2 empirically examined the effect of suffix frequency on school-aged children's judgments of primary stress placement. Findings suggest that age and suffix frequency both play a role in children's awareness of stress placement.

General slowing in language impairment: methodological considerations in testing the hypothesis

Although the general slowing hypothesis of language impairment (LI) is well established, the conventional method to test the hypothesis is controversial. This paper compares the usual method, ordinary least squares regression (OLS), with another method, hierarchical linear modeling with random coefficients (HLM). The analyses used available response time (RT) data from studies of perceptual-motor, cognitive, and language skills of LI and chronological-age-matched (CA) groups. The data set included RT measures from 25 studies investigating 20 different tasks (e.g., auditory detection, mental rotation, and word recognition tasks). OLS and HLM analyses of the RT data yielded very different results. OLS supported general slowing for the LI groups, and indicated that they were significantly slower than CA groups across studies by an overall estimate of 10%. HLM indicated a larger average extent of LI slowing (18%). However, the variability around this average was much greater than that yielded by OLS, and the extent of slowing was not statistically significant. Importantly, HLM showed a significant difference in the RT relation between LI and CA groups across studies, indicating that study-specific slowing, rather than general slowing across studies, was present. A separate HLM analysis of two types of language tasks, picture naming and word recognition, was performed. Although the extent of slowing was equivalent across these tasks, the slowing was minimal (2%) and not significant. Methodological limitations of each analysis to assess general slowing are highlighted.

Testing the generalized slowing hypothesis in specific language impairment

This study investigated the proposition that children with specific language impairment (SLI) show a generalized slowing of response time (RT) across tasks compared to chronological-age (CA) peers. Three different theoretical models consistent with the hypothesis of generalized slowing--a proportional, linear, and nonlinear model--were examined using regression analyses of group RT data. Each model was an excellent fit with the RT data. The most parsimonious model indicated that the SLI group was proportionally slower than the CA group. Mean RTs of the SLI group were about one fifth slower across tasks than the CA group's mean RTs. Less slowing was evident for a subgroup of young children with expressive SLI than for children with mixed (expressive and receptive) SLI. Although the mean RT data reflected many individual SLI children's RT performance, not all SLI children showed generalized slowing.