Lexical access in aphasic and nonaphasic speakers

Neural regions essential for distinct cognitive processes underlying picture naming

We hypothesized that distinct cognitive processes underlying oral and written picture naming depend on intact function of different, but overlapping, regions of the left hemisphere cortex, such that the distribution of tissue dysfunction in various areas can predict the component of the naming process that is disrupted. To test this hypothesis, we evaluated 116 individuals within 24 h of acute ischaemic stroke using a battery of oral and written naming and other lexical tests, and with magnetic resonance diffusion and perfusion imaging to identify the areas of tissue dysfunction. Discriminant function analysis, using the degree of hypoperfusion in various Brodmann's areas--BA 22 (including Wernicke's area), BA 44 (part of Broca's area), BA 45 (part of Broca's area), BA 21 (inferior temporal cortex), BA 37 (posterior, inferior temporal/fusiform gyrus), BA 38 (anterior temporal cortex) and BA 39 (angular gyrus)--as discriminant variables, classified patients on the basis of the primary component of the naming process that was impaired (defined as visual, semantics, modality-independent lexical access, phonological word form, orthographic word form and motor speech by the pattern of performance and types of errors across lexical tasks). Additionally, linear regression analysis demonstrated that the areas contributing the most information to the identification of patients with particular levels of impairment in the naming process were largely consistent with evidence for the roles of these regions from functional imaging. This study provides evidence that the level of impairment in the naming process reflects the distribution of tissue dysfunction in particular regions of the left anterior, inferior and posterior middle/superior temporal cortex, posterior inferior frontal and inferior parietal cortex. While occipital cortex is also critical for picture naming, it is likely that bilateral occipital damage is necessary to disrupt visual recognition. These findings provide new evidence that a network of brain regions supports naming, but separate components of this network are differentially required for distinct cognitive processes or representations underlying the complex task of naming pictures.

Phonological skills and disfluency levels in preschool children who stutter

The relation between stuttering and aspects of language, including phonology, has been investigated for many years. Whereas past literature reported that the incidence of phonological difficulties is higher for children who stutter when compared to normally fluent children, the suggestion of association between the two disorders also drew several critical evaluations. Nevertheless, only a limited amount of information exists concerning the manner and extent to which the speech sound errors exhibited by young children who stutter, close to stuttering onset, is related to the characteristics of their stuttering, such as its severity. Conversely, information is limited regarding the effects a child's phonological skills may have on his/her stuttering severity. The current study investigated the mutual relations between these two factors in 28 carefully selected preschool children near the onset of their stuttering. The children, 20 boys and 8 girls, ranged in age from 25 to 38 months, with a mean of 32.2 months. The phonological skills of two groups with different ratings of stuttering were compared. Similarly, the stuttering severities of two groups with different levels of phonological skills (minimal deviations-moderate deviations) were compared. No statistically significant differences were found for either of the two factors. Inspection of the data revealed interesting individual differences.

LEARNING OUTCOMES

The reader will be able to list: (1) differences in the phonological skills of preschool children whose stuttering is severe as compared to children whose stuttering is mild and (2) differences in stuttering severity in preschool children with minimal phonological deviations as compared to children with moderate phonological deviations.

Lexical and post-lexical phonological representations in spoken production

Theories of spoken word production generally assume a distinction between at least two types of phonological processes and representations: lexical phonological processes that recover relatively arbitrary aspects of word forms from long-term memory and post-lexical phonological processes that specify the predictable aspects of phonological representations. In this work we examine the spoken production of two brain-damaged individuals. We use their differential patterns of accuracy across the tasks of spoken naming and repetition to establish that they suffer from distinct deficits originating fairly selectively within lexical or post-lexical processes. Independent and detailed analyses of their spoken productions reveal contrasting patterns that provide clear support for a distinction between two types of phonological representations: those that lack syllabic and featural information and are sensitive to lexical factors such as lexical frequency and neighborhood density, and those that include syllabic and featural information and are sensitive to detailed properties of phonological structure such as phoneme frequency and syllabic constituency.

Phonological neighborhood and word frequency effects in the stuttered disfluencies of children who stutter

PURPOSE

The purpose of this study was to examine (a) the role of neighborhood density (number of words that are phonologically similar to a target word) and frequency variables on the stuttering-like disfluencies of preschool children who stutter, and (b) whether these variables have an effect on the type of stuttering-like disfluency produced.

METHOD

A 500+ word speech sample was obtained from each participant (N = 15). Each stuttered word was randomly paired with the firstly produced word that closely matched it in grammatical class, familiarity, and number of syllables/phonemes. Frequency, neighborhood density, and neighborhood frequency values were obtained for the stuttered and fluent words from an online database.

RESULTS

Findings revealed that stuttered words were lower in frequency and neighborhood frequency than fluent words. Words containing part-word repetitions and sound prolongations were also lower in frequency and/or neighborhood frequency than fluent words, but these frequency variables did not have an effect on single-syllable word repetitions. Neighborhood density failed to influence the susceptibility of words to stuttering, as well as the type of stuttering-like disfluency produced.

CONCLUSIONS

In general, findings suggest that neighborhood and frequency variables not only influence the fluency with which words are produced in speech, but also have an impact on the type of stuttering-like disfluency produced.

Re-visiting "semantic facilitation" of word retrieval for people with aphasia: facilitation yes but semantic no

Previous research has shown that word-to-picture matching for targets that cannot be named at pre-test results in improved naming relative to untreated control items for people with aphasia. This paper replicates and extends this finding and investigates its source. Is the effect a result of priming of semantic representations, or of post-semantic mechanisms in word retrieval? The first experiment shows that word-to-picture matching with unrelated distractors improves naming at short (2-3 minutes) and long (up to 25 minute) lags. There was no effect of being made aware of the relationship between word-to-picture matching and picture naming. People who have a semantic impairment improve only with a short lag between word-to-picture matching and naming. Participants with less semantic impairment show larger priming effects that are equal at short and long lags between word-to-picture matching and naming. The second experiment shows that the facilitation effect is just as large for word-to-picture matching with unrelated distractors as with semantically-related distractors. Furthermore, overall there was no difference between matching with coordinate items and with associated items. The results of these experiments show that facilitation of naming by word-to-picture matching in people with aphasia cannot be a result of the priming of semantic representations. Instead they are consistent with two effects: word-to-picture matching results in priming at a lemma level for aphasic people with a semantic impairment that is only found with a short lag between word-to-picture matching and naming. Word-to-picture matching causes priming of the lemma to output lexicon entry mapping that benefits participants with less semantic impairment that is evident at both a short and long lag between word-to-picture matching and naming. These findings fit well with previous research on repetition priming of naming with normal subjects.

Exploring the dynamics of aphasic word production using the picture-word interference task: a case study

In this study, we use an auditory picture-word interference task to examine an anomic individual, NP. NP produced semantic errors in picture naming, but his comprehension was relatively well preserved. In the task, pictures to be named were accompanied by semantically, phonologically or unrelated distractors, presented at onsets ranging from -200ms (before target) to +400ms (after target). Naming latencies were measured. A group of 12 older controls showed semantic interference (slower latencies with semantic than with unrelated distractors), which was significant at -200ms, and steadily diminished across later onsets. In contrast, at 0ms, NP showed powerful semantic facilitation. There were no significant semantic effects at other onsets, but the trends, particularly at later onsets, were towards interference. Phonological effects for NP were in the same direction as for controls (facilitation) but were of greater magnitude. Indeed, NP showed a reliable facilitatory effect at 0ms (and trends at -200ms and +200ms), but a similar trend in controls failed to reach significance. Within recent models of this task, in which semantic facilitation effects are attributed to an early, pre-lexical semantic processing stage, NP's pattern indicates that semantic processing is abnormally prolonged. The phonological facilitation effects are also consistent with this interpretation. We discuss their implications and future applications of the task to aphasia.

Observing the what and when of language production for different age groups by monitoring speakers' eye movements

Research on adult age differences in language production has traditionally focused on either the production of single words or the properties of language samples. Older adults are more prone to word retrieval failures than are younger adults (e.g., ). Older adults also tend to produce fewer ideas per utterance and fewer left-branching syntactic structures (e.g., ). The use of eye movement monitoring in the study of language production allows researchers to examine word production processes in the context of multiword utterances, bridging the gap between behavior in word production studies and spontaneous speech samples. This paper outlines one view of how speakers plan and produce utterances, summarizes the literature on age-related changes in production, presents an overview of the published research on speakers' gaze during picture description, and recaps a study using eye movement monitoring to explore age-related changes in language production.

Effectiveness of contextual repetition priming treatments for anomia depends on intact access to semantics

Naming of two semantically impaired aphasic patients was treated with the contextual repetition priming technique, which involves repeated repetition of names of pictures that are related semantically, phonologically, or are unrelated. Our previous studies using this technique have suggested that patients with impaired access to lexical-semantic representations benefit in the short-term from this treatment technique, but show no long-term improvement in naming. In contrast, patients with good access to semantics show short- and long-term benefits from this treatment. Here we report two studies of treatment for two individuals with aphasia affecting access to lexical semantics and anomia but spared access to input and output phonology and spared conceptual semantics. We predicted that they would show short-term facilitation from the contextual priming, but no long-term improvements in naming. The results confirmed the prediction. An account of this pattern is offered within the framework of an interactive activation model of word retrieval. Additionally, we discuss alternative techniques for addressing naming deficits when access to semantics is impaired.

Semantic priming over unrelated trials: evidence for different effects in word and picture naming

Two naming experiments are reported that replicated previous findings of semantic interference as a result of naming related word or picture primes three trials before picture targets. We also examined whether semantic interference occurred when the materials were reversed and picture or word primes were named before word targets. The interest in semantic interference during word naming followed a suggestion made by Humphreys, Lloyd-Jones, and Fias (1995) that word naming, like picture naming, may be reliant on a semantic route to name retrieval when the two stimuli are mixed. In contrast to their findings, we found no evidence for semantic interference during target word naming; in fact, we found facilitation from related picture primes. No priming was found for the related word prime and word target condition. The data allow us to rule out the possibility that word naming is reliant on a semantic route when mixed with pictures in this priming paradigm and to conclude that there is no clear evidence of semantic activation during word naming. We also conclude, in line with other research, that word naming and picture naming involve different processes.

Speech errors reflect newly learned phonotactic constraints

Speech errors reveal the speaker's implicit knowledge of phonotactic constraints, both languagewide constraints (e.g., /K/ cannot be a syllable onset when one is speaking English) and experimentally induced constraints (e.g., /k/ cannot be an onset during the experiment). Four experiments investigated the acquisition of novel 2nd-order constraints, in which the allowable position of a consonant depends on some other property of the syllable (e.g., /k/ can only be an onset if the vowel is /I/). Participants recited strings of syllables that exhibited the novel constraints throughout a 4-day experiment. Their errors reflected the newly learned constraints but not until the 2nd day of training. This contrasts with previous research showing that errors become sensitive to 1st-order constraints almost immediately. A model that learns to assign phonemes to syllable positions is presented. It attributes the relative slowness of the acquisition of 2nd-order constraints to the self-interfering property of these constraints.

Phonological activation of category coordinates during speech planning is observable in children but not in adults: evidence for cascaded processing

There is a long-standing debate in the area of speech production on the question of whether only words selected for articulation are phonologically activated (as maintained by serial-discrete models) or whether this is also true for their semantic competitors (as maintained by forward-cascading and interactive models). Past research has addressed this issue by testing whether retrieval of a target word (e.g., cat) affects--or is affected by--the processing of a word that is phonologically related to a semantic category coordinate of the target (e.g., doll, related to dog) and has consistently failed to obtain such mediated effects in adult speakers. The authors present a series of experiments demonstrating that mediated effects are present in children (around age 7) and diminish with increasing age. This observation provides further evidence for cascaded models of lexical retrieval.

Phonological and conceptual activation in speech comprehension

We propose that speech comprehension involves the activation of token representations of the phonological forms of current lexical hypotheses, separately from the ongoing construction of a conceptual interpretation of the current utterance. In a series of cross-modal priming experiments, facilitation of lexical decision responses to visual target words (e.g., time) was found for targets that were semantic associates of auditory prime words (e.g., date) when the primes were isolated words, but not when the same primes appeared in sentence contexts. Identity priming (e.g., faster lexical decisions to visual date after spoken date than after an unrelated prime) appeared, however, both with isolated primes and with primes in prosodically neutral sentences. Associative priming in sentence contexts only emerged when sentence prosody involved contrastive accents, or when sentences were terminated immediately after the prime. Associative priming is therefore not an automatic consequence of speech processing. In no experiment was there associative priming from embedded words (e.g., sedate-time), but there was inhibitory identity priming (e.g., sedate-date) from embedded primes in sentence contexts. Speech comprehension therefore appears to involve separate distinct activation both of token phonological word representations and of conceptual word representations. Furthermore, both of these types of representation are distinct from the long-term memory representations of word form and meaning.

Effect of semantic naming treatment on crosslinguistic generalization in bilingual aphasia

PURPOSE

The effect of semantic naming treatment on crosslinguistic generalization was investigated in 3 participants with English-Spanish bilingual aphasia.

METHOD

A single-subject experimental designed was used. Participants received semantic treatment to improve naming of English or Spanish items, while generalization was tested to untrained semantically related items in the trained language and translations of the trained and untrained items in the untrained language.

RESULTS

Results demonstrated a within- and across-languages effect on generalization related to premorbid language proficiencies. Participant 1 (P1; equal premorbid proficiency across languages) showed within-language generalization in the trained language (Spanish) as well as crosslinguistic generalization to the untrained language (English). Participant 2 (P2) and Participant (P3) were more proficient premorbidly in English. With treatment in English, P2 showed within-language generalization to semantically related items, but no crosslinguistic generalization. With treatment in Spanish, both P2 and P3 exhibited no within-language generalization, but crosslinguistic generalization to English (dominant language) occurred. Error analyses indicated an evolution of errors as a consequence of treatment.

CONCLUSIONS

These results are preliminary because all participants were not treated in both languages. However, the results suggest that training the less dominant language may be more beneficial in facilitating crosslinguistic generalization than training the more proficient language in an unbalanced bilingual individual.

Learning artificial phonotactic constraints: time course, durability, and relationship to natural constraints

G. S. Dell, K. D. Reed, D. R. Adams, and A. S. Meyer (2000) proposed a "breadth-of-constraint" continuum on phoneme errors, using artificial experiment-wide constraints to investigate a putative middle ground between local and language-wide constraints. The authors report 5 experiments that test the idea of the continuum and the location of the experiment-wide constraints within it. Experiments 1 and 2 replicated the findings of Dell et al. on the experiment-wide constraints but showed only chance adherence to the local positional constraints. Experiment 3 showed that the latter constraints are uniquely affected by the form of practice used. Experiments 4 and 5 investigated the time course and robustness of the experimental constraints by reversing them during testing. This caused no difficulty when occurring between blocks (Experiment 4) but caused short-lived disruption when occurring within block (Experiment 5). The authors propose that the results do not support the idea of a continuum, but that the experiment-wide constraints reflect a local biasing of language-wide constraints, probably related to the need for rapid learning.

Retrieval of names in face and object naming in an interference study

Two experiments using the interference paradigm are reported. In the first experiment, the participants spoke aloud the names of celebrities and the names of objects when presented with pictures while hearing distractors. In the case of proper names, we replicated the data obtained by Izaute and Bonin (2001) using the interference paradigm with a proper name written naming task. In the case of common names, the results replicated those obtained by Shriefers, Meyer, and Levelt (1990). In the second experiment, the participants produced the names of celebrities when presented with their faces while hearing distractors that were either proper names associated with the celebrities (associate condition), that belonged to a different professional category (different condition), or that corresponded to the proper names of the celebrities (identical condition). For negative SOAs, "associate" distractors were found to increase latencies compared to the "different category" condition. The implications of the findings for proper name retrieval are briefly discussed.

Constituent structure and linear order in language production: evidence from subject-verb agreement

A number of studies have shown that structural factors play a much larger role than the linear order of words during the production of grammatical agreement. These findings have been used as evidence for a stage in the production process at which hierarchical relations between constituents have been established (a necessary precursor to agreement), but before the final linear order of words is determined. The current article combines evidence from off-line ratings, online production studies, and a corpus analysis in support of the view that linear order effects do exist. These findings have implications both for theories of agreement production and language production more generally.

"Tip of the fingers" experiences by deaf signers: insights into the organization of a sign-based lexicon

The "tip of the fingers" phenomenon (TOF) for sign language parallels the "tip of the tongue" phenomenon (TOT) for spoken language. During a TOF, signers are sure they know a sign but cannot retrieve it. Although some theories collapse semantics and phonology in sign language and thus predict that TOFs should not occur, TOFs were elicited in the current study. Like TOTs, TOFs often resolve spontaneously, commonly involve targets that are proper names, and frequently include partial access to phonology. Specifically, signers were more likely to retrieve a target sign's handshape, location, and orientation than to retrieve its movement. Signers also frequently recalled the first letter of a finger-spelled word. The existence of TOFs supports two-stage retrieval and a division between semantics and phonology in American Sign Language. The partial phonological information available during TOFs suggests that phonological features are accessed more simultaneously during lexical access for signed language than during lexical access for spoken language.

Semantic and phonological context effects in speech error repair

When speakers repair speech errors, they plan the repair in the context of an abandoned word (the error) that is usually similar in meaning or form. Two picture-naming experiments tested whether the error's lexical representations influence repair planning. Context pictures were sometimes replaced with target pictures; the picture names were related in meaning or form or were unrelated. The authors measured target picture-naming latencies separately for trials in which the context name was interrupted or completed. Interrupted trials showed semantic interference and phonological facilitation, whereas completed trials showed semantic facilitation and phonological interference. Thus, errors influence repair production. The authors explain the polarity of these effects in terms of the literature on context effects in word production.

A structural account of phonological paraphasias

The aim of this study is to develop a partial theory of phonological paraphasias which has some cross-syndrome and cross-linguistic validity. It is based on the distinction between content and structural units and emphasizes the role of the latter. The notion of structure holds the key to an understanding of the differences among the following three types of data: slips of the tongue, slips of the pen (defined as errors committed by healthy, competent adults), and paraphasias. A comparison of these three data types reveals that slips of the pen and paraphasias display striking similarities whereas slips of the tongue stand apart. This pattern emerges very clearly in an analysis of nine empirical effects all of which are found to be of a structural nature. On the basis of these results, it is argued that both the written output of normals and the oral output of aphasics are generated under a reduced structural representation (i.e., weak activation of structural nodes). However, the reasons for the diminished sensitivity to structure are not the same in the two modalities. While the impoverished structural representation is a likely consequence of the relatively slow production rate in writing, it may stem from an impaired transmission of activation among structural nodes in aphasia. By contrast, the normal speaking process occurs under the sway of a full-fledged structural representation. Hence, slips of the tongue are highly sensitive to structural effects.

Naming concepts: evidence of two routes

This study examines a parallel distributed processing (PDP) model (partly based on the Wernicke-Lichtheim information processing model) that posits two routes for naming concepts, whole word and phonological. To test the two naming route hypothesis of this model, we performed confrontation naming tests that were either uncued, semantically cued, or phonologically cued in a patient with naming impairment due to Broca's aphasia. In spoken language and in uncued naming to confrontation, word retrieval was severely impaired and marked by semantic but no phonemic paraphasic errors. With semantic cues, naming behavior was unchanged; however, with phonological cues, naming success was enhanced but frequent phonemic paraphasias were produced. These results suggest that the patient spontaneously engaged the whole word naming route, but when given phonological cues, he engaged an alternative phonological naming route that incorporated phonological sequence knowledge.

Cumulative semantic inhibition in picture naming: experimental and computational studies

We report an experiment in which subjects named 120 pictures, consisting of series of five pictures drawn from each of 24 semantic categories (and intermixed with 45 fillers). The number of intervening trials (lag) between successive presentations of members of the same category varied from two to eight. Subjects' naming latencies were slowed by 30 ms for each preceding member of the category. This effect was both cumulative and linear, and unrelated to the lag elapsing since the previous presentation of a category member. These results definitively demonstrate the occurrence of cumulative interference for word retrieval by prior retrieval of other exemplars of the same semantic category-cumulative semantic inhibition. We claim that this inhibition effect could only occur if the spoken word production system possesses three specific properties (competition, priming, and sharing of semantic activation). We provide computational-modelling evidence in support of this claim. We show that no current theory of spoken word production has all of these properties. In their current form, all these theories are falsified by these results. We briefly discuss the obstacles that may be encountered by current models were they modified to account for our findings.

Becoming syntactic

Psycholinguistic research has shown that the influence of abstract syntactic knowledge on performance is shaped by particular sentences that have been experienced. To explore this idea, the authors applied a connectionist model of sentence production to the development and use of abstract syntax. The model makes use of (a) error-based learning to acquire and adapt sequencing mechanisms and (b) meaning-form mappings to derive syntactic representations. The model is able to account for most of what is known about structural priming in adult speakers, as well as key findings in preferential looking and elicited production studies of language acquisition. The model suggests how abstract knowledge and concrete experience are balanced in the development and use of syntax.

Aphasic Deficits in Syntactic Processing

Two main classes of theories of deficits in syntactic processing in aphasia have been suggested: impairments affecting specific syntactic operations and reductions in resources available for syntactic processing. This paper reviews the data upon which such theories are based and argues that they may support only the latter type of model.

From tip-of-the-tongue (TOT) data to theoretical implications in two steps: When more TOTs means better retrieval

Two experiments in which participants named pictured objects with difficult or easier names, and a reanalysis and review of published data, reveal that problematic measures used in previous studies obscured the implications of group differences in tip-of-the-tongue (TOT) rates. In Experiment 1, increased age led to more TOTs for difficult but not easy targets. In Experiment 2, bilinguals had more TOTs than monolinguals for easy targets but fewer TOTs for difficult targets. The authors developed a theoretically motivated measure that clarifies the implications of TOT data by linking all responses elicited in the TOT paradigm with either success or failure in completing 2 retrieval steps in current models of language production. The 2-step analysis reveals a common mechanism for the age and bilingualism effects and implies that age has both positive and negative effects on retrieval.

Refractory effects in picture naming as assessed in a semantic blocking paradigm

In the cyclic semantic blocking paradigm participants repeatedly name sets of objects with semantically related names (homogeneous sets) or unrelated names (heterogeneous sets). The naming latencies are typically longer in related than in unrelated sets. In Experiment 1 we replicated this semantic blocking effect and demonstrated that the effect only arose after all objects of a set had been shown and named once. In Experiment 2, the objects of a set were presented simultaneously (instead of on successive trials). Evidence for semantic blocking was found in the naming latencies and in the gaze durations for the objects, which were longer in homogeneous than in heterogeneous sets. For the gaze-to-speech lag between the offset of gaze on an object and the onset of the articulation of its name, a repetition priming effect was obtained but no blocking effect. Experiment 3 showed that the blocking effect for speech onset latencies generalized to new, previously unnamed lexical items. We propose that the blocking effect is due to refractory behaviour in the semantic system.

When zebras become painted donkeys: Grammatical gender and semantic priming interact during picture integration in a spoken Spanish sentence

This study investigates the contribution of grammatical gender to integrating depicted nouns into sentences during on-line comprehension, and whether semantic congruity and gender agreement interact using two tasks: naming and semantic judgement of pictures. Native Spanish speakers comprehended spoken Spanish sentences with an embedded line drawing, which replaced a noun that either made sense or not with the preceding sentence context and either matched or mismatched the gender of the preceding article. In Experiment 1a (picture naming) slower naming times were found for gender mismatching pictures than matches, as well as for semantically incongruous pictures than congruous ones. In addition, the effects of gender agreement and semantic congruity interacted; specifically, pictures that were both semantically incongruous and gender mismatching were named slowest, but not as slow as if adding independent delays from both violations. Compared with a neutral baseline, with pictures embedded in simple command sentences like "Now please say ____", both facilitative and inhibitory effects were observed. Experiment 1b replicated these results with low-cloze gender-neutral sentences, more similar in structure and processing demands to the experimental sentences. In Experiment 2, participants judged a picture's semantic fit within a sentence by button-press; gender agreement and semantic congruity again interacted, with gender agreement having an effect on congruous but not incongruous pictures. Two distinct effects of gender are hypothesised: a "global" predictive effect (observed with and without overt noun production), and a "local" inhibitory effect (observed only with production of gender-discordant nouns).

Prosody and lemma selection

In three picture-naming experiments, we examined the effect of prosodic context on the synonyms people use to name pictures in Mandarin Chinese. This was done without time pressure. The results showed that when monosyllabic and bisyllabic synonyms (e.g., hen/chicken) were embedded in a context of pictures with either bisyllabic or trisyllabic names, participants gave bisyllabic responses to the synonyms more often than they did in a condition without such a context. The difference was very similar in magnitude in both the bisyllabic and trisyllabic contextual conditions. These results suggest that people are biased toward using synonyms that have numbers of syllables equal or similar to those of the prosodic context. If it is assumed that prosodic effects originate at a stage of processing beyond the lemma level, then this suggests either that multiple phonological forms of synonyms can be activated or that there is feedback from prosodic processing that influences lemma selection.

Investigation of a new intervention for children with word-finding problems

BACKGROUND

Around one-quarter of children attending language support services have difficulty in retrieving words. Therapy studies with such children have shown that both semantic and phonological techniques can improve word finding. A new approach to intervention is described using a computerized aid that converts letters into sound cues.

AIMS

(1) To assess the word-finding abilities in a small series of children with word-finding difficulties. (2) To investigate whether intervention with a computerized aid can improve children's ability to find words. (3) To evaluate the effect of therapy on connected speech (using the Test of Word Finding in Discourse) and in relation to children's, parents' and other practitioners' views (using a questionnaire). (4) To understand the outcome in relation to an interactive model of speech production.

METHODS & PROCEDURES

Five children (aged 6:10-10:7) were assessed on a variety of background measures. Following baseline assessment, two sets of items were included in therapy: a research set (with matched control items) and a further set selected for their functional relevance for each child. Intervention using the computerized aid took place once a week for half a term (6 weeks).

OUTCOMES & RESULTS

The children differed from one another in their language development and non-verbal abilities, but all had difficulties in word retrieval. All children showed significant improvement in naming intervention items after therapy. This effect was maintained half a term later. Despite very different profiles, the children benefited similarly from the intervention, suggesting a common processing source for change. After the intervention, two children showed a significant reduction in word-finding behaviours (e.g. use of substitutions, repetitions and empty words) on the Test of Word Finding in Discourse. The views of participants, parents and professionals were varied but generally positive.

CONCLUSIONS

The main effect of therapy can be understood, in relation to an interactive model of speech production, as strengthening links from meaning to form. Use of the aid in therapy improved word finding for targeted items and this occurred within a clinically realistic timeframe. The finding that the gains in word retrieval maintained suggests that the intervention can be functionally useful if target items are chosen appropriately. Measurable change for two children in connected speech suggests wider benefits can also occur. Overall, the aid can be a useful additional tool for therapists/teachers working with children with this difficulty.

A re-evaluation of the nature of speech errors in normal and disordered speakers

It is well known that speech errors in normal and aphasic speakers share certain key characteristics. Traditionally, many of these errors are regarded as serial misorderings of abstract phonological segments, which maintain the phonetic well-formedness of the utterance. The current paper brings together the results of several articulatory studies undertaken independently for both subject populations. These show that, in an error, instead of one segment substituting for another, two segments are often produced simultaneously even though only one segment may be heard. Such data pose problems for current models of speech production by suggesting that the commonly assumed dichotomous distinction between phonological and phonetic errors may not be tenable in the current form or may even be altogether redundant.

Contrasting effects of phonological priming in aphasic word production

Two fluent aphasics, IG and GL, performed a phonological priming task in which they repeated an auditory prime then named a target picture. The two patients both had selective deficits in word production: they were at or near ceiling on lexical comprehension tasks, but were significantly impaired in picture naming. IG's naming errors included both semantic and phonemic paraphasias, as well as failures to respond, whereas GL's errors were mainly phonemic and formal paraphasias. The two patients responded very differently to phonological priming: IG's naming was facilitated (both accuracy and speed) only by begin-related primes (e.g. ferry-feather), whereas GL benefited significantly only from end-related primes (e.g. brother-feather), showing no more than a facilitatory trend with begin-related primes. We interpret these results within a two-stage model of word production, in which begin-related and end-related primes are said to operate at different stages. We then discuss implications for models of normal and aphasic word production in general and particularly with respect to sequential aspects of the phonological encoding process.

Age of acquisition effects in picture naming: evidence for a lexical-semantic competition hypothesis

In many tasks the effects of frequency and age of acquisition (AoA) on reaction latencies are similar in size. However, in picture naming the AoA-effect is often significantly larger than expected on the basis of the frequency-effect. Previous explanations of this frequency-independent AoA-effect have attributed it to the organisation of the semantic system or to the way phonological word forms are stored in the mental lexicon. Using a semantic blocking paradigm, we show that semantic context effects on naming latencies are more pronounced for late-acquired than for early-acquired words. This interaction between AoA and naming context is likely to arise during lexical-semantic encoding, which we put forward as the locus for the frequency-independent AoA-effect.

Making Syntax of Sense: Number Agreement in Sentence Production

Grammatical agreement flags the parts of sentences that belong together regardless of whether the parts appear together. In English, the major agreement controller is the sentence subject, the major agreement targets are verbs and pronouns, and the major agreement category is number. The authors expand an account of number agreement whose tenets are that pronouns acquire number lexically, whereas verbs acquire it syntactically but with similar contributions from number meaning and from the number morphology of agreement controllers. These tenets were instantiated in a model using existing verb agreement data. The model was then fit to a new, more extensive set of verb data and tested with a parallel set of pronoun data. The theory was supported by the model's outcomes. The results have implications for the integration of words and structures, for the workings of agreement categories, and for the nature of the transition from thought to language.

Context Effects on Lexical Choice and Lexical Activation

Speakers are regularly confronted with the choice among lexical alternatives when referring to objects, including basic-level names (e.g., car) and subordinate-level names (e.g., Beetle). Which of these names is eventually selected often depends on contextual factors. The present article reports a series of picture-word interference experiments that explored how the designated target name (basic level vs. subordinate level) and contextual constraints rendering the name alternative either appropriate or inappropriate affect lexical activation and lexical choice. The experimental data demonstrate clear context effects on the eventual lexical choice. However, they also show that alternative nonselected object names are phonologically activated, even if a constraining context makes these alternative names currently inappropriate.

Long-Lasting Semantic Context Effects in the Spoken Production of Object Names

A number of recent studies have found that objects are named more slowly in the context of same-category items than in the context of items from various semantic categories. Several experiments reported here indicated that this semantic effect is relatively persistent because it was essentially unaffected by the presence of interspersed filler items. The authors suggest that the effect is specific to the retrieval of lexical-semantic codes and characterize mechanisms that could support the effect at this processing level, such as incremental learning in the links between conceptual and lexical codes and the temporary increase of lexical resting levels. The results underscore the necessity of incorporating mechanisms of long-term adaptation into current models of spoken production.

Disentangling the web: neologistic perseverative errors in jargon aphasia

This article explores the relationship between the neologisms and perseverative errors produced by KVH, a man with severe neologistic jargon aphasia. Detailed examination of KVH's level of language processing breakdown revealed mild difficulties with phonological encoding and severe difficulties accessing the lexical form of the word. Many of KVH's neologisms contained phonemes perseverated from previous neologisms, suggesting an integral relationship between the production of neologisms and the perseveration of phonemes. Furthermore, KVH's patterns of whole word (total)and phonological (blended) perseverations reflected his proposed underlying language processing deficits, consistent with recent literature on perseveration (e.g.,Cohen and Dehaene, 1998). However, the simple binary distinction oftotalandblendedperseveration is proposed to be somewhat limited for understanding the underlying nature of KVH's complex neologistic errors. Possible explanations regarding the mechanisms underlying the production of KVH's neologistic and perseverative errors also are discussed.

Role of grammatical gender and semantics in German word production

Semantic substitution errors (e.g., saying "arm" when "leg" is intended) are among the most common types of errors occurring during spontaneous speech. It has been shown that grammatical gender of German target nouns is preserved in the errors (E. Mane, 1999). In 3 experiments, the authors explored different accounts of the grammatical gender preservation effect in German. In all experiments, semantic substitution errors were induced using a continuous naming paradigm. In Experiment 1, it was found that gender preservation disappeared when speakers produced bare nouns. Gender preservation was found when speakers produced phrases with determiners marked for gender (Experiment 2) but not when the produced determiners were not marked for gender (Experiment 3). These results are discussed in the context of models of lexical retrieval during production.