Lexical access in aphasic and nonaphasic speakers

To select or to wait? Response to the commentaries

In [Nozari, N., & Hepner, C. R. (2018). To select or to wait? The importance of criterion setting in debates of competitive lexical selection. Cognitive Neuropsychology. Advance online publication. doi:10.1080/02643294.2018.1476335], we proposed a theoretical framework for reconciling two seemingly irreconcilable theories of lexical selection: competitive vs. non-competitive selection. The key point in this framework is the division of language production into two separate-albeit interacting-systems: a decision-making framework and a multi-layered system which maps meaning to sound. Technically, this can be accomplished by superimposing a signal detection model onto the distributions of conflict derived from the core dynamics of mapping semantic features to lexical representations. Based on this framework, we argued that a flexible selection criterion could accommodate patterns predicted by both competitive and non-competitive models of lexical selection. Five excellent commentaries posed various questions regarding the necessity, applicability, and scope of the proposed framework. This paper addresses those questions.

The Methodological Quality of Short-Term/Working Memory Treatments in Poststroke Aphasia: A Systematic Review

Purpose The aims of this systematic review are to provide a critical overview of short-term memory (STM) and working memory (WM) treatments in stroke aphasia and to systematically evaluate the internal and external validity of STM/WM treatments. Method A systematic search was conducted in February 2014 and then updated in December 2016 using 13 electronic databases. We provided descriptive characteristics of the included studies and assessed their methodological quality using the Risk of Bias in N-of-1 Trials quantitative scale ( Tate et al., 2015 ), which was completed by 2 independent raters. Results The systematic search and inclusion/exclusion procedure yielded 17 single-case or case-series studies with 37 participants for inclusion. Nine studies targeted auditory STM consisting of repetition and/or recognition tasks, whereas 8 targeted attention and WM, such as attention process training including n-back tasks with shapes and clock faces as well as mental math tasks. In terms of their methodological quality, quality scores on the Risk of Bias in N-of-1 Trials scale ranged from 4 to 17 ( M = 9.5) on a 0-30 scale, indicating a high risk of bias in the reviewed studies. Effects of treatment were most frequently assessed on STM, WM, and spoken language comprehension. Transfer effects on communication and memory in activities of daily living were tested in only 5 studies. Conclusions Methodological limitations of the reviewed studies make it difficult, at present, to draw firm conclusions about the effects of STM/WM treatments in poststroke aphasia. Further studies with more rigorous methodology and stronger experimental control are needed to determine the beneficial effects of this type of intervention. To understand the underlying mechanisms of STM/WM treatment effects and how they relate to language functioning, a careful choice of outcome measures and specific hypotheses about potential improvements on these measures are required. Future studies need to include outcome measures of memory functioning in everyday life and psychosocial functioning more generally to demonstrate the ecological validity of STM and WM treatments.

"Twisting fingers": The case for interactivity in typed language production

Despite the obvious linguistic nature of typing, current psychological models of typing are, to a large extent, divorced from models of spoken language production. This gap has left unanswered many questions regarding the cognitive architecture of typing. In this article we advocate the use of a psycholinguistic framework for studying typing, by showing that such a framework could reveal important similarities and differences between spoken and typed production. Specifically, we investigated the interaction between the lexical and postlexical layers by using a phenomenon known in spoken production as the "repeated-phoneme effect." Participants typed four-word sequences of "finger-twisters" (equivalent to tongue-twisters in spoken production), in which the vowel in the last two words was either repeated (e.g., "fog top") or not (e.g., "fog tip"). We found reliably more migration errors between the consonants of the two typed words when the vowel was repeated, even after the effect of phonology was accounted for. This finding is compatible with an interactive typing system in which postlexical representations send feedback to lexical representations and reveals similar dynamics between spoken and typed production. Additional analyses showed further similarities to spoken production, such as distinct lexical and postlexical error categories, but also revealed that typing errors were much more likely than spoken errors to violate phonotactic constraints. These results provide the first demonstration of feedback between the postlexical and lexical layers in typing, and more generally demonstrate the utility of adopting a psycholinguistic framework tailored specifically to the study of typing.

Multi-factor analysis in language production: Sequential sampling models mimic and extend regression results

For multi-factor analyses of response times, descriptive models (e.g., linear regression) arguably constitute the dominant approach in psycholinguistics. In contrast empirical cognitive models (e.g., sequential sampling models, SSMs) may fit fewer factors simultaneously, but decompose the data into several dependent variables (a multivariate result), offering more information to analyze. While SSMs are notably popular in the behavioural sciences, they are not significantly developed in language production research. To contribute to the development of this modelling in language, we (i) examine SSMs as a measurement modelling approach for spoken word activation dynamics, and (ii) formally compare SSMs to the default method, regression. SSMs model response activation or selection mechanisms in time, and calculate how they are affected by conditions, persons, and items. While regression procedures also model condition effects, it is only in respect to the mean RT, and little work has been previously done to compare these approaches. Through analyses of two language production experiments, we show that SSMs reproduce regression predictors, and further extend these effects through a multivariate decomposition (cognitive parameters). We also examine a combined regression-SSM approach that is hierarchical Bayesian, which can jointly model more conditions than classic SSMs, and importantly, achieve by-item modelling with other conditions. In this analysis, we found that spoken words principally differed from one another by their activation rates and production times, but not their thresholds to be activated.

Direct electrical stimulation of the left frontal aslant tract disrupts sentence planning without affecting articulation

Sentence production involves mapping from deep structures that specify meaning and thematic roles to surface structures that specify the order and sequencing of production ready elements. We propose that the frontal aslant tract is a key pathway for sequencing complex actions with deep hierarchical structure. In the domain of language, and primarily with respect to the left FAT, we refer to this as the 'Syntagmatic Constraints On Positional Elements' (SCOPE) hypothesis. One prediction made by the SCOPE hypothesis is that disruption of the frontal aslant tract should disrupt sentence production at grammatical phrase boundaries, with no disruption of articulatory processes.  We test this prediction in a patient undergoing direct electrical stimulation mapping of the frontal aslant tract during an awake craniotomy to remove a left frontal brain tumor. We found that stimulation of the left FAT prolonged inter-word durations at the start of grammatical phrases, while inter-word durations internal to noun phrases were unaffected, and there was no effect on intra-word articulatory duration. These results provide initial support for the SCOPE hypothesis, and motivate novel directions for future research to explore the functions of this recently discovered component of the language system.

Continuous theta burst stimulation over right pars triangularis facilitates naming abilities in chronic post-stroke aphasia by enhancing phonological access

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) has been used experimentally to facilitate naming abilities in individuals with chronic post-stroke aphasia. However, little is known about how rTMS confers clinical improvement, hampering its therapeutic value. The present study investigated the characteristics of naming failure that improve following administration of continuous theta burst stimulation (cTBS)-an inhibitory form of rTMS-to the right pars triangularis (rPTr) in persons with chronic aphasia.

METHODS

Eleven participants with chronic aphasia following left hemisphere stroke named pictures prior to and immediately following cTBS of the rPTr and a control site (vertex) in separate sessions. Prior to stimulation, we obtained two baseline measurements of picture naming ability to determine the extent and type (i.e., phonological vs. semantic) of naming impairment. Items presented for naming during stimulation were those that were named incorrectly in one or both of the baseline sessions (i.e., inconsistent vs. wrong items, respectively). Analyses assessed whether cTBS effects differed depending on the severity and/or type of naming impairment.

RESULTS

Relative to vertex, cTBS of the rPTr improved naming of inconsistent, but not wrong, items for individuals with more severe baseline naming impairment. Critically, baseline phonological but not semantic naming impairment severity marginally correlated with improved accuracy overall, and significantly correlated with decreased phonological errors following rPTr stimulation.

CONCLUSION

CTBS of the rPTr enhances naming by facilitating phonological access during word retrieval, indicating that individuals whose naming impairment is localized to this stage of processing may be most likely to benefit from this rTMS approach.

Significance of speech production errors on cross-linguistic processing in Sepedi-English individuals with bilingual aphasia: a case series analysis

BACKGROUND

Bilingual aphasia forms a significant part of speech-language pathologists' (SLP) caseload, globally, and specifically in South Africa. Few tools supporting clinical decision-making are available due to limited understanding of typical and disordered cross-linguistic processing (how the languages interact). Speech errors may provide insight about "hidden" bilingual mechanisms.

OBJECTIVES

To determine what speech errors can impart about cross-linguistic processing, as well as, associated language and impairment variables in Sepedi-English individuals with aphasia.

METHOD

The case series included six participants, purposively selected from three rehabilitation sites in South Africa. Detailed language and clinical profiles were obtained. Participants performed a confrontation naming task in their most dominant (MDL) and less dominant language (LDL). Responses were audio recorded, transcribed, and analyzed for overall accuracy and error type in MDL and LDL; verified by a Sepedi-speaking linguist and a qualified SLP.

RESULTS

(1) No statistically significant differences in MDL-LDL naming accuracy were found, supporting recent literature of simultaneous inter-activation of both languages and shared word retrieval mechanisms. All types of speech errors occurred, and semantic errors were produced most frequently and consistently in each participant's MDL and LDL. (2) Language proficiency, language recovery patterns, and aphasia type (Broca's and Anomic) and severity (mild and/or moderate) appeared to be more strongly linked to cross-linguistic processing than Sepedi-English linguistic differences and age of acquisition of both languages.

CONCLUSIONS

Participants with bilingual aphasia may use typical cross-linguistic and word retrieval mechanisms, concurring with current theories of bilingualism. Findings are preliminary, warranting investigations of other language tasks, modalities, pairs, and related variables.

Self-reported inner speech relates to phonological retrieval ability in people with aphasia

Many individuals with aphasia report the ability to say words in their heads despite spoken naming difficulty. Here, we examined individual differences in the experience of inner speech (IS) in participants with aphasia to test the hypotheses that self-reported IS reflects intact phonological retrieval and that articulatory output processing is not essential to IS. Participants (N = 53) reported their ability to name items correctly internally during a silent picture-naming task. We compared this measure of self-reported IS to spoken picture naming and a battery of tasks measuring the underlying processes required for naming (i.e., phonological retrieval and output processing). Results from three separate analyses of these measures indicate that self-reported IS relates to phonological retrieval and that speech output processes are not a necessary component of IS. We suggest that self-reported IS may be a clinically valuable measure that could assist in clinical decision-making regarding anomia diagnosis and treatment.

Processing of task-irrelevant words of different frequency values: a visual mismatch negativity study

This study examined electrophysiological correlates of early and automatic word access. Chinese single-character words of high frequency and low frequency were peripherally presented in an oddball paradigm. Participants were instructed to carry out a centrally presented nonlinguistic colour-tracking task and ignore the lexical stimuli presented on both sides. Early visual mismatch negativity (vMMN) effects at 120-150 and 200-300 ms were elicited only by high-frequency characters, whereas low-frequency characters yielded vMMN only after 300 ms. This contrast of vMMN effects indicating lexical processing in an attention-deprived condition is suggested to result from stronger memory traces for high-frequency characters in comparison with low-frequency characters.

Phonological Interlopers Tend to Repeat When Tip-of-the-Tongue States Repeat

We elicited tip-of-the-tongue (TOT) states to replicate the finding that TOTs repeat for individual words. Humphreys and colleagues have attributed this error repetition phenomenon to implicit learning of the mappings between the lemma and phonology. We also examined whether or not interlopers - repeated information that persistently comes to mind - repeat during TOT states for individual words, along with the type of interlopers. Participants were given a TOT test and the same TOT test one week later. The test consisted of the presentation of a definition and participants indicated if they knew the word, did not know the word, or if they were in a TOT state. Participants were also given 15 s to think aloud about the target word on both test and retest. We found that information repeats significantly more often for repeated TOT states (26%) than repeated Don't Know states (13%). We also found that participants experienced significantly more repeated phonological interlopers during a repeated TOT state (59%) versus a repeated Don't Know state (12%). Theoretically, the results may suggest that the TOT state is best described as a subthreshold state, and that within this subthreshold state there is a specific erroneous pattern of activation (akin to a local minimum) rather than a non-specific pattern of activation. These findings are an important constraint toward the development of a more formal explanation of recurring TOTs.

A Test Battery for Inner Speech Functions

Objective

Inner speech, or the ability to talk to yourself in your head, is one of the most ubiquitous phenomena of everyday experience. Recent years have seen growing interest in the role and function of inner speech in various typical and cognitively impaired populations. Although people vary in their ability to produce inner speech, there is currently no test battery which can be used to evaluate people's inner speech ability. Here we developed a test battery which can be used to evaluate individual differences in the ability to access the auditory word form internally.

Methods

We developed and standardized five tests: rhyme judgment of pictures and written words, homophone judgment of written words and non-words, and judgment of lexical stress of written words. The tasks were administered to adult healthy native British English speakers (age range 20-72, n = 28-97, varies between tests).

Results

In all tests, some items were excluded based on low success rates among participants, or documented regional variability in accent. Level of education, but not age, correlated with task performance for some of the tasks, and there were no gender difference in performance.

Conclusion

A process of standardization resulted in a battery of tests which can be used to assess natural variability of inner speech abilities among English speaking adults.

The Subjective Experience of Inner Speech in Aphasia Is a Meaningful Reflection of Lexical Retrieval

Purpose Individuals with aphasia often report that they feel able to say words in their heads, regardless of speech output ability. Here, we examine whether these subjective reports of successful "inner speech" (IS) are meaningful and test the hypothesis that they reflect lexical retrieval. Method Participants were 53 individuals with chronic aphasia. During silent picture naming, participants reported whether or not they could say the name of each item inside their heads. Using the same items, they also completed 3 picture-based tasks that required phonological retrieval and 3 matched auditory tasks that did not. We compared participants' performance on these tasks for items they reported being able to say internally versus those they reported being unable to say internally. Then, we examined the relationship of psycholinguistic word features to self-reported IS and spoken naming accuracy. Results Twenty-six participants reported successful IS on nearly all items, so they could not be included in the item-level analyses. These individuals performed correspondingly better than the remaining participants on tasks requiring phonological retrieval, but not on most other language measures. In the remaining group ( n = 27), IS reports related item-wise to performance on tasks requiring phonological retrieval, but not to matched control tasks. Additionally, IS reports were related to 3 word characteristics associated with lexical retrieval, but not to articulatory complexity; spoken naming accuracy related to all 4 word characteristics. Six participants demonstrated evidence of unreliable IS reporting; compared with the group, they also detected fewer errors in their spoken responses and showed more severe language impairments overall. Conclusions Self-reported IS is meaningful in many individuals with aphasia and reflects lexical phonological retrieval. These findings have potential implications for treatment planning in aphasia and for our understanding of IS in the general population.

Lexical selection with competing distractors: Evidence from left temporal lobe lesions

According to the competition account of lexical selection in word production, conceptually driven word retrieval involves the activation of a set of candidate words in left temporal cortex and competitive selection of the intended word from this set, regulated by frontal cortical mechanisms. However, the relative contribution of these brain regions to competitive lexical selection is uncertain. In the present study, five patients with left prefrontal cortex lesions (overlapping in ventral and dorsal lateral cortex), eight patients with left lateral temporal cortex lesions (overlapping in middle temporal gyrus), and 13 matched controls performed a picture-word interference task. Distractor words were semantically related or unrelated to the picture, or the name of the picture (congruent condition). Semantic interference (related vs. unrelated), tapping into competitive lexical selection, was examined. An overall semantic interference effect was observed for the control and left-temporal groups separately. The left-frontal patients did not show a reliable semantic interference effect as a group. The left-temporal patients had increased semantic interference in the error rates relative to controls. Error distribution analyses indicated that these patients had more hesitant responses for the related than for the unrelated condition. We propose that left middle temporal lesions affect the lexical activation component, making lexical selection more susceptible to errors.

Verbal working memory and linguistic long-term memory: Exploring the lexical cohort effect

Numerous studies have shown that verbal working memory (vWM) performance is strongly influenced by linguistic knowledge, with items more familiar at sublexical, lexical, and/or semantic levels leading to higher vWM recall performance. Among the many different psycholinguistic variables whose impact on vWM has been studied, the lexical cohort effect is one of the few effects that has not yet been explored. The lexical cohort effect reflects the fact that words sharing their first phonemes with many other words (e.g. alcove, alligator, alcohol…) are typically responded to more slowly as compared to words sharing their first phonemes with a smaller number of words. In a pilot experiment (Experiment 1), we manipulated the lexical cohort effect in an immediate serial recall task and found no effect. Experiment 2 showed that, in a lexical decision task, participants responded more quickly to items stemming from small cohorts, showing that the material used in Experiment 1 allowed for a valid manipulation of the cohort effect. Experiment 3, using stimuli from Experiment 2 associated with maximal cohort effects during lexical decision, failed again to reveal a cohort effect in an immediate serial recall task. We argue that linguistic knowledge impacts vWM performance via continuous interactive activation within the linguistic system, which is not the case for the lexical cohort variable that may influence language processing only at the initial stages of stimulus activation.

Neither Cue Familiarity nor Semantic Cues Increase the Likelihood of Repeating a Tip-of-the-Tongue State

Psycholinguistic and metacognition researchers mostly disagree on what constitutes a tip-of-the-tongue (TOT) state. Psycholinguists argue that TOT states occur when there is a transmission of activation failure between the lemma and phonology levels of word production (e.g., Burke, MacKay, Worthley, & Wade, 1991). Metacognition researchers argue that the TOT state is better described as a subjective experience caused by a mechanism that assesses the likelihood of recall from memory. One sub-hypothesis of the metacognitive account of TOT states is the cue familiarity hypothesis, which suggests that a TOT state may occur when cues elicit a feeling of familiarity (Metcalfe, Schwartz, & Joaquim, 1993). We conducted three experiments to evaluate the cue familiarity hypothesis of TOT state etiology. Experiment 1 included a test-retest TOT task with identical definitions (i.e., cues that should elicit familiarity) versus alternative definitions. TOTs were as likely to repeat for alternative definitions across test and retest as identical definitions, which is inconsistent with the cue familiarity hypothesis. Experiment 2 included the same task layout as Experiment 1, but we used very different cues (pictures versus descriptions for famous people). Again, we found that TOTs tended to repeat regardless of whether or not prompts were identical. In Experiment 3, we presented either a picture and description simultaneously or a description only on the first test, followed by a description only on retest. We found that giving participants an extra semantic cue did not change the probability of repeating a TOT state. These findings suggest that repeated TOT states do not occur due to cue familiarity nor is the locus of the TOT state at the semantic level of the word production/word recall system. Therefore, we argue that the results point towards a success of lemma access, but then failure of the lemma-to-phonology mappings.

The Relationship Between Non-Orthographic Language Abilities and Reading Performance in Chronic Aphasia: An Exploration of the Primary Systems Hypothesis

PURPOSE

This study investigated the relationship between non-orthographic language abilities and reading in order to examine assumptions of the primary systems hypothesis and further our understanding of language processing poststroke.

METHOD

Performance on non-orthographic semantic, phonologic, and syntactic tasks, as well as oral reading and reading comprehension tasks, was assessed in 43 individuals with aphasia. Correlation and regression analyses were conducted to determine the relationship between these measures. In addition, analyses of variance examined differences within and between reading groups (within normal limits, phonological, deep, or global alexia).

RESULTS

Results showed that non-orthographic language abilities were significantly related to reading abilities. Semantics was most predictive of regular and irregular word reading, whereas phonology was most predictive of pseudohomophone and nonword reading. Written word and paragraph comprehension were primarily supported by semantics, whereas written sentence comprehension was related to semantic, phonologic, and syntactic performance. Finally, severity of alexia was found to reflect severity of semantic and phonologic impairment.

CONCLUSIONS

Findings support the primary systems view of language by showing that non-orthographic language abilities and reading abilities are closely linked. This preliminary work requires replication and extension; however, current results highlight the importance of routine, integrated assessment and treatment of spoken and written language in aphasia.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.7403963.

Intervention for children with word-finding difficulties: a parallel group randomised control trial

PURPOSE

The study investigated the outcome of a word-web intervention for children diagnosed with word-finding difficulties (WFDs).

METHOD

Twenty children age 6-8 years with WFDs confirmed by a discrepancy between comprehension and production on the Test of Word Finding-2, were randomly assigned to intervention (n = 11) and waiting control (n = 9) groups. The intervention group had six sessions of intervention which used word-webs and targeted children's meta-cognitive awareness and word-retrieval.

RESULT

On the treated experimental set (n = 25 items) the intervention group gained on average four times as many items as the waiting control group (d = 2.30). There were also gains on personally chosen items for the intervention group. There was little change on untreated items for either group.

CONCLUSION

The study is the first randomised control trial to demonstrate an effect of word-finding therapy with children with language difficulties in mainstream school. The improvement in word-finding for treated items was obtained following a clinically realistic intervention in terms of approach, intensity and duration.

Monitoring of language selection errors in switching: Not all about conflict

Although bilingual speakers are very good at selectively using one language rather than another, sometimes language selection errors occur. To investigate how bilinguals monitor their speech errors and control their languages in use, we recorded event-related potentials (ERPs) in unbalanced Dutch-English bilingual speakers in a cued language-switching task. We tested the conflict-based monitoring model of Nozari and colleagues by investigating the error-related negativity (ERN) and comparing the effects of the two switching directions (i.e., to the first language, L1 vs. to the second language, L2). Results show that the speakers made more language selection errors when switching from their L2 to the L1 than vice versa. In the EEG, we observed a robust ERN effect following language selection errors compared to correct responses, reflecting monitoring of speech errors. Most interestingly, the ERN effect was enlarged when the speakers were switching to their L2 (less conflict) compared to switching to the L1 (more conflict). Our findings do not support the conflict-based monitoring model. We discuss an alternative account in terms of error prediction and reinforcement learning.

One hundred fifty years after Donders: Insights from unpublished data, a replication, and modeling of his reaction times

Mental processes take a measurable amount of time, which was discovered by Donders one hundred fifty years ago. He reports process durations in his classic study with the a-, b-, and c-methods (i.e., simple, choice, go/no-go) using a speech repetition task. His reaction time pattern was a < c < b. He reasoned that the c - a difference gives the discrimination duration, and the b - c difference the choice duration. A few years later, Wundt criticized the c-method by arguing that it does involve a choice (i.e., whether or not to respond, which is an act of executive control), whereas Donders maintained that it may not involve full discrimination. The substance of this historical controversy relates closely to modern issues in the study of reaction times. Here, I show that an analysis of unpublished data from a handwritten laboratory notebook of Donders reveals no b - c difference for his students, supporting Wundt's concern. Moreover, a replication of Donders' study using his original stimulus lists yielded only a small b - c difference for myself, supporting Wundt. A computer simulation using a modern model of speech repetition indicates that the difference between Donders and his students may plausibly result from choice in the c-method. To conclude, unpublished data, a replication, and modern modeling resolve a 150-year-old issue, stressing the importance of examining individual differences and executive control in performance.

Left frontotemporal effective connectivity during semantic feature judgments in patients with chronic aphasia and age-matched healthy controls

Traditional models of neural reorganization of language skills in patients with chronic stroke-induced aphasia (PWA) propose activation of reperfused or spared left hemisphere tissue results in the most favorable language outcomes. However, these models do not fully explain variable behavioral recovery patterns observed in chronic patients. Instead, investigation of connectivity patterns of critical network nodes may elucidate better-informed recovery models. In the present study, we combined fMRI and dynamic causal modeling (DCM) to examine effective connectivity of a simple three-node left hemisphere network during a semantic feature decision task in 25 PWA and 18 age-matched neurologically intact healthy controls. The DCM model space utilized in Meier, Kapse, & Kiran (2016), which was organized according to exogenous input to one of three regions (i.e., left inferior frontal gyrus, pars triangularis [LIFGtri], left posterior middle temporal gyrus [LpMTG], or left middle frontal gyrus [LMFG]) implicated in various levels of lexical-semantic processing, was interrogated. This model space included all possible combinations of uni- and bidirectional task-modulated connections between LIFGtri, LMFG and LpMTG, resulting in 72 individual models that were partitioned into three separate families (i.e., Family #1: Input to LIFGtri, Family #2: Input to LMFG, Family #3: Input to LpMTG). Family-wise Bayesian model selection revealed Family #2: Input to LMFG best fit both patient and control data at a group level. Both groups relied heavily on LMFG's modulation of the other two model regions. By contrast, between-group differences in task-modulated coupling of LIFGtri and LpMTG were observed. Within the patient group, the strength of activity in LIFGtri and connectivity of LpMTG → LIFGtri were positively associated with lexical-semantic abilities inside and outside of the scanner, whereas greater recruitment of LpMTG was associated with poorer lexical-semantic skills.

Assessment of linguistic and verbal short-term memory components of language abilities in aphasia

Some current models of aphasia emphasize a role of short-term memory in the processing of language and propose that the language impairment in aphasia involves impairment to cognitive processes that activate and maintain representations of words over the time-period needed to support single word and multiple word tasks, including verbal span tasks. This paper reports normative data from 39 people with aphasia and 16 age-matched neurotypical controls on a test battery for aphasia that assesses effects of increased short-term/working memory load on word and sentence processing as well as effects of linguistic variations on verbal short-term memory abilities Two concepts are discussed that capture the unique potential of this test battery for research and clinical practice: specificity of diagnosis and sensitivity to all degrees of aphasia severity, including mild aphasia. An analysis is included that shows how the performance of individuals with mild aphasia who achieve normal level of performance on the Western Aphasia Battery (Kertesz, 2006) show a decline in a temporal delay condition that is greater than performance of control participants. We also report preliminary data showing differential effects of adding a time interval before a response or between items to be compared: reduced accuracy for some individuals with aphasia and improved accuracy for others. The theoretical and clinical importance of this finding is discussed, as well as the overall potential for this test battery to be used in research and as a clinical tool. Finally, we discuss the relevance of this test battery to investigate functional communication abilities in aphasia.

The neuroanatomy of speech sequencing at the syllable level

Correctly ordering a sequence of speech sounds is a crucial aspect of speech production. Although studies have yielded a rich body of data on the neural substrates of visuomotor sequencing and sequence learning, research on brain regions and their functions involving speech sequence production hasn’t attracted much attention until recently. Previous functional MRI studies manipulating the complexity of sequences at the phonemic, syllabic, and suprasyllabic levels have revealed a network of motor-related cortical and sub-cortical speech regions. In this study, we directly compared human brain activity measured with functional MRI during processing of a sequence of syllables compared with the same syllables processed individually. Among a network of regions independently identified as being part of the sensorimotor circuits for speech production, only the left posterior inferior frontal gyrus (pars opercularis, lIFG), the supplementary motor area (SMA), and the left inferior parietal lobe (lIPL) responded more during the production of syllable sequences compared to producing the same syllables articulated one at a time.

Listeners and readers generalize their experience with word meanings across modalities

Research has shown that adults' lexical-semantic representations are surprisingly malleable. For instance, the interpretation of ambiguous words (e.g., bark) is influenced by experience such that recently encountered meanings become more readily available (Rodd et al., 2016, 2013). However, the mechanism underlying this word-meaning priming effect remains unclear, and competing accounts make different predictions about the extent to which information about word meanings that is gained within one modality (e.g., speech) is transferred to the other modality (e.g., reading) to aid comprehension. In two Web-based experiments, ambiguous target words were primed with either written or spoken sentences that biased their interpretation toward a subordinate meaning, or were unprimed. About 20 min after the prime exposure, interpretation of these target words was tested by presenting them in either written or spoken form, using word association (Experiment 1, N = 78) and speeded semantic relatedness decisions (Experiment 2, N = 181). Both experiments replicated the auditory unimodal priming effect shown previously (Rodd et al., 2016, 2013) and revealed significant cross-modal priming: primed meanings were retrieved more frequently and swiftly across all primed conditions compared with the unprimed baseline. Furthermore, there were no reliable differences in priming levels between unimodal and cross-modal prime-test conditions. These results indicate that recent experience with ambiguous word meanings can bias the reader's or listener's later interpretation of these words in a modality-general way. We identify possible loci of this effect within the context of models of long-term priming and ambiguity resolution. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Impaired Lexical Selection and Fluency in Post-Stroke Aphasia

BACKGROUND

Deficits in fluent language production are a hallmark of aphasia and may arise from impairments at different levels in the language system. It has been proposed that difficulty resolving lexical competition contributes to fluency deficits.

AIMS

The present study tested this hypothesis in a novel way: by examining whether narrative speech production fluency is associated with difficulty resolving lexical competition in spoken word recognition as measured by sensitivity to phonological neighborhood density.

METHODS & PROCEDURES

Nineteen participants with aphasia and 15 neurologically intact older adults identified spoken words that varied in phonological neighborhood density and were presented in moderate noise.

OUTCOMES & RESULTS

Neurologically intact participants exhibited the standard inhibitory effect of phonological neighborhood density on response times: slower recognition of spoken words from denser neighborhoods. Among participants with aphasia, the inhibitory effect of phonological neighborhood density (less accurate recognition of spoken words from denser neighborhoods) was smaller for participants with greater fluency. The neighborhood effect was larger for participants with greater receptive vocabulary knowledge, indicating that the fluency effect was not a result of general lexical deficits.

CONCLUSIONS

These results are consistent with the hypothesis that impaired lexical selection is a contributing factor in fluency deficits in post-stroke aphasia.

Development of bidirectional phono-semantic activation in toddlers

A mediated priming effect refers to the activation of a target via a mediator previously activated by a prime. This effect has been found at 24 months of age for phono-semantic links: a prime ( cup) activates a target ( dog) via a mediator ( cat), providing evidence of activation in a forward direction (phonological to semantic). Interactive models, however, propose that activation propagates in both forward and backward directions between processing levels. This study investigated the development of bidirectional co-activation of phonological and semantic levels of processing in Spanish-speaking toddlers. In a primed preferential looking task, participants were exposed to an unlabelled prime image, followed by the presentation of two images, a target and a distractor. In Experiment 1, when images with a semantic-phonological relationship were presented, both 24- and 30-month-olds preferred to look at the named target with a relationship to the prime image ( dog- cat- cup). However, when an unrelated target image was named, 24-month-olds preferred to look at the target, but 30-month-olds did not. In Experiment 2, both 24- and 30-month-olds preferred to look at a target with a phono-semantic relationship to the prime ( cup- cat- dog) over an unrelated target. These results provide strong evidence of differences in the development of forward and backward interactions between semantic and phonological processing levels.

Semantic interference in speech error production in a randomized continuous naming task: Evidence from aphasia

Naming pictures from the same semantic category hinders subsequent naming from that category (i.e., semantic interference), irrespective of the number of intervening different-category exemplars named. Persistent semantic interference has been well documented in chronometric studies, and has been attributed to experience-driven adjustments in the strength of connections between semantic and lexical representations. However, whether parallel effects exist in speech error data remains unclear. In the current study, people with aphasia, a speaker population prone to naming errors, provided naming responses to a large picture corpus presented in random order that comprised multiple exemplars drawn from several different categories. We found persistent semantic interference in the task in semantic error rates specifically, and that semantic similarity between consecutive related exemplars modulated the effect. The results provide further evidence for the presumed lexical-semantic locus and mechanism(s) underlying semantic interference.

Predicting confrontation naming item difficulty

BACKGROUND

Item response theory (IRT; Lord & Novick, 1968) is a psychometric framework that can be used to model the likelihood that an individual will respond correctly to an item. Using archival data (Mirman et al., 2010), Fergadiotis, Kellough, and Hula (2015) estimated difficulty parameters for the Philadelphia Naming Test (PNT; Roach, Schwartz, Martin, Grewal, & Brecher, 1996) using the 1-parameter logistic IRT model. Although the use of IRT in test development is advantageous, its reliance on sample sizes exceeding 200 participants make it difficult to implement in aphasiology. Therefore, alternate means of estimating the item difficulty of confrontation naming test items warrant investigation. In a preliminary study aimed at automatic item calibration, Swiderski, Fergadiotis, and Hula (2016) regressed the difficulty parameters from the PNT on word length, age of acquisition (Kuperman et al., 2012), lexical frequency as quantified by the Log10CD index (Brysbaert & New, 2009), and naming latency (Székely et al., 2003). Although this model successfully explained a substantial proportion of variance in the PNT difficulty parameters, a substantial proportion (20%) of the response time data were missing. Further, only 39% of the picture stimuli from Székely and colleagues (2003) were identical to those on the PNT. Given that the IRT sample size requirements limit traditional calibration approaches in aphasiology and that the initial attempts in predicting IRT difficulty parameters in our pilot study were based on incomplete response time data this study has two specific aims.

AIMS

To estimate naming latencies for the 175 items on the PNT, and assess the utility of psycholinguistic variables and naming latencies for predicting item difficulty.

METHODS AND PROCEDURES

Using a speeded picture naming task we estimated mean naming latencies for the 175 items of the Philadelphia Naming test in 44 cognitively healthy adults. We then re-estimated the model reported by Swiderski et al (2016) with the new naming latency data.

RESULTS

The predictor variables described above accounted for a substantial proportion of the variance in the item difficulty parameters (Adj. R 2 = .692).

CONCLUSIONS

In this study we demonstrated that word length, age of acquisition, lexical frequency, and naming latency from neurotypical young adults usefully predict picture naming item difficulty in people with aphasia. These variables are readily available or easily obtained and the regression model reported may be useful for estimating confrontation naming item difficulty without the need for collection of response data from large samples of people with aphasia.

The Roles of Retrieval Practice Versus Errorless Learning in Strengthening Lexical Access in Aphasia

Purpose

The purpose of this study was to determine how 2 methods known to improve naming impairment in aphasia (i.e., retrieval practice and errorless learning) affect lexical access. We hypothesized that instances of naming during retrieval practice use and strengthen item-specific connections in each of 2 stages of lexical access: Stage 1, meaning-to-word connections, and Stage 2, word-to-phonology connections. In contrast, errorless learning prioritizes opportunities for repeating words, which we expect to primarily strengthen item-specific connections in Stage 2 because repetition circumvents the need for semantically driven word retrieval.

Method

We tested the outcomes of retrieval practice versus errorless learning training for items that were selected because the naming errors they elicited suggested weakened connections at Stage 1 or at Stage 2 of lexical access for each of 10 individuals with chronic aphasia. Each participant's Stage 1 items and Stage 2 items were divided evenly between the 2 training conditions. Naming tests were administered 1 day and 1 week after training to assess retention of training gains. We also examined whether the participants' pretraining naming error profiles were associated with the relative efficacy of retrieval practice versus errorless learning.

Results

The posttraining naming tests showed an advantage of retrieval practice over errorless learning for Stage 1 items and an advantage of errorless learning over retrieval practice for Stage 2 items. In addition, greater percentages of phonological error naming responses prior to training were associated with greater posttraining accuracy in the errorless learning condition relative to the retrieval practice condition.

Conclusions

The findings suggest that the advantage of retrieval practice for naming impairment in aphasia largely results from greater strengthening of practiced semantic-lexical connections compared with errorless learning, which prioritizes repetition and, therefore, mainly confers strengthening of practiced lexical-phonological connections. Understanding how specific training conditions improve naming can help predict the relative efficacy of each method for individuals with aphasia.

Word repetition and retrieval practice effects in aphasia: Evidence for use-dependent learning in lexical access

This study tested the hypothesis that a use-dependent learning mechanism operates at each of two stages of lexical access: retrieval of a word from semantics ("Stage 1"), followed by retrieval of the word's constituent phonemes ("Stage 2"). Two participants with aphasia were selected due to their contrasting types of naming impairment (Stage 1 versus Stage 2 difficulty). For each participant, items were assigned to naming training that involved retrieval practice (retrieval of the name from semantics) or repetition practice (hear the name and orally repeat it). Naming tests were administered one day and one week after training. The results supported the predicted training effects: (a) Because successful naming via retrieval practice requires both Stage 1 and Stage 2, this technique uses and strengthens item-specific connections in both stages. (b) Because word repetition circumvents semantically driven retrieval, this technique primarily uses and strengthens item-specific connections in Stage 2.

To select or to wait? The importance of criterion setting in debates of competitive lexical selection

Competitive accounts of lexical selection propose that the activation of competitors slows down the selection of the target. Non-competitive accounts, on the other hand, posit that target response latencies are independent of the activation of competing items. In this paper, we propose a signal detection framework for lexical selection and show how a flexible selection criterion affects claims of competitive selection. Specifically, we review evidence from neurotypical and brain-damaged speakers and demonstrate that task goals and the state of the production system determine whether a competitive or a non-competitive selection profile arises. We end by arguing that there is conclusive evidence for a flexible criterion in lexical selection, and that integrating criterion shifts into models of language production is critical for evaluating theoretical claims regarding (non-)competitive selection.

A cognitive psychometric model for assessment of picture naming abilities in aphasia

Picture naming impairments are a typical feature of stroke-induced aphasia. Overall accuracy and rates of different error types are used to make inferences about the severity and nature of damage to the brain's language network. Currently available assessment tools for picture naming accuracy treat it as a unidimensional measure, while assessment tools for error types treat items homogenously, contrary to findings from psycholinguistic investigations of word production. We created and tested a new cognitive psychometric model for assessment of picture naming responses, using cognitive theory to specify latent processing decisions during the production of a naming attempt, and using item response theory to separate the effects of item difficulty and participant ability on these internal processing decisions. The model enables multidimensional assessment of latent picture naming abilities on a common scale, with a relatively large cohort for normative reference. We present the results of 4 experiments testing our interpretation of the model's parameters, as they apply to picture naming predictions, lexical properties of the items, statistical properties of the lexicon, and participants' scores on other tests. We also created a website for researchers and clinicians to analyze item-level data using our model, providing estimates of latent abilities and percentile scores, as well as credible intervals to help gauge the reliability of the estimated model parameters and identify meaningful changes. To the extent that the model is successful, the estimated parameter values may aid in treatment decisions and progress monitoring, or they may help elucidate the functional properties of brain networks. (PsycINFO Database Record

A Systematic Review of Semantic Feature Analysis Therapy Studies for Aphasia

PURPOSE

The purpose of this study was to review treatment studies of semantic feature analysis (SFA) for persons with aphasia. The review documents how SFA is used, appraises the quality of the included studies, and evaluates the efficacy of SFA.

METHOD

The following electronic databases were systematically searched (last search February 2017): Academic Search Complete, CINAHL Plus, E-journals, Health Policy Reference Centre, MEDLINE, PsycARTICLES, PsycINFO, and SocINDEX. The quality of the included studies was rated. Clinical efficacy was determined by calculating effect sizes (Cohen's d) or percent of nonoverlapping data when d could not be calculated.

RESULTS

Twenty-one studies were reviewed reporting on 55 persons with aphasia. SFA was used in 6 different types of studies: confrontation naming of nouns, confrontation naming of verbs, connected speech/discourse, group, multilingual, and studies where SFA was compared with other approaches. The quality of included studies was high (Single Case Experimental Design Scale average [range] = 9.55 [8.0-11]). Naming of trained items improved for 45 participants (81.82%). Effect sizes indicated that there was a small treatment effect.

CONCLUSIONS

SFA leads to positive outcomes despite the variability of treatment procedures, dosage, duration, and variations to the traditional SFA protocol. Further research is warranted to examine the efficacy of SFA and generalization effects in larger controlled studies.

Frontotemporal stimulation modulates semantically-guided visual search during confrontation naming: A combined tDCS and eye tracking investigation

Transcranial direct current stimulation (tDCS) was paired with eye tracking to elucidate contributions of frontal, temporoparietal and anterior temporal cortex to early visual search patterns during picture naming (e.g., rapid visual scanning to diagnostic semantic features). Neurotypical adults named line drawings of objects prior to and following tDCS in three separate sessions, each employing a unique electrode montage. The gaze data revealed montage by stimulation (pre/post) interaction effects characterized by longer initial visual fixations (mean difference = 89 ms; Cohen's d = .8) and cumulative fixation durations (mean difference = 98 ms; Cohen's d = .9) on key semantic features (e.g., the head of an animal) after cathodal frontotemporal stimulation relative to the pre-stimulation baseline. We interpret these findings as reflecting a tDCS-induced modulation of semantic contributions of the anterior temporal lobe(s) to top-down influences on object recognition. Further, we discuss implications for the optimization of tDCS for the treatment of anomia in aphasia.

Unification of behavioural, computational and neural accounts of word production errors in post-stroke aphasia

Neuropsychological assessment, brain imaging and computational modelling have augmented our understanding of the multifaceted functional deficits in people with language disorders after stroke. Despite the volume of research using each technique, no studies have attempted to assimilate all three approaches in order to generate a unified behavioural-computational-neural model of post-stroke aphasia. The present study included data from 53 participants with chronic post-stroke aphasia and merged: aphasiological profiles based on a detailed neuropsychological assessment battery which was analysed with principal component and correlational analyses; measures of the impairment taken from Dell's computational model of word production; and the neural correlates of both behavioural and computational accounts analysed by voxel-based correlational methodology. As a result, all three strands coincide with the separation of semantic and phonological stages of aphasic naming, revealing the prominence of these dimensions for the explanation of aphasic performance. Over and above three previously described principal components (phonological ability, semantic ability, executive-demand), we observed auditory working memory as a novel factor. While the phonological Dell parameter was uniquely related to phonological errors/factor, the semantic parameter was less clear-cut, being related to both semantic errors and omissions, and loading heavily with semantic ability and auditory working memory factors. The close relationship between the semantic Dell parameter and omission errors recurred in their high lesion-correlate overlap in the anterior middle temporal gyrus. In addition, the simultaneous overlap of the lesion correlate of omission errors with more dorsal temporal regions, associated with the phonological parameter, highlights the multiple drivers that underpin this error type. The novel auditory working memory factor was located along left superior/middle temporal gyrus and ventral inferior parietal lobe. The present study fused computational, behavioural and neural data to gain comprehensive insights into the nature of the multifaceted presentations in aphasia. Our unified account contributes enhanced knowledge on dimensions explaining chronic post-stroke aphasia, the variety of factors affecting inter-individual variability, the neural basis of performance, and potential clinical implications.

Masked Repetition Priming Treatment for Anomia

PURPOSE

Masked priming has been suggested as a way to directly target implicit lexical retrieval processes in aphasia. This study was designed to investigate repeated use of masked repetition priming to improve picture naming in individuals with anomia due to aphasia.

METHOD

A single-subject, multiple-baseline design was used across 6 people with aphasia. Training involved repeated exposure to pictures that were paired with masked identity primes or sham primes. Two semantic categories were trained in series for each participant. Analyses assessed treatment effects, generalization within and across semantic categories, and effects on broader language skills, immediately and 3 months after treatment.

RESULTS

Four of the 6 participants improved in naming trained items immediately after treatment. Improvements were generally greater for items that were presented in training with masked identity primes than items that were presented repeatedly during training with masked sham primes. Generalization within and across semantic categories was limited. Generalization to broader language skills was inconsistent.

CONCLUSION

Masked repetition priming may improve naming for some individuals with anomia due to aphasia. A number of methodological and theoretical insights into further development of this treatment approach are discussed.

Verbal short-term memory capacities and executive function in semantic and syntactic interference resolution during sentence comprehension: Evidence from aphasia

This study examined the role of verbal short-term memory (STM) and executive function (EF) underlying semantic and syntactic interference resolution during sentence comprehension for persons with aphasia (PWA) with varying degrees of STM and EF deficits. Semantic interference was manipulated by varying the semantic plausibility of the intervening NP as subject of the verb and syntactic interference was manipulated by varying whether the NP was another subject or an object. Nine PWA were assessed on sentence reading times and on comprehension question performance. PWA showed exaggerated semantic and syntactic interference effects relative to healthy age-matched control subjects. Importantly, correlational analyses showed that while answering comprehension questions, PWA' semantic STM capacity related to their ability to resolve semantic but not syntactic interference. In contrast, PWA' EF abilities related to their ability to resolve syntactic but not semantic interference. Phonological STM deficits were not related to the ability to resolve either type of interference. The results for semantic interference are consistent with prior findings indicating a role for semantic but not phonological STM in sentence comprehension, specifically with regard to maintaining semantic information prior to integration. The results for syntactic interference are consistent with the recent findings suggesting that EF is critical for syntactic processing.

Links Between Short-Term Memory and Word Retrieval in Aphasia

PURPOSE

This study explored the relationship between anomia and verbal short-term memory (STM) in the context of an interactive activation language processing model.

METHOD

Twenty-four individuals with aphasia and reduced STM spans (i.e., impaired immediate serial recall of words) completed a picture-naming task and a word pair repetition task (a measure of verbal STM). Correlations between verbal STM and word retrieval errors made on the picture-naming task were examined.

RESULTS

A significant positive correlation between naming accuracy and verbal span length was found. More intricate verbal STM analyses examined the relationship between picture-naming error types (i.e., semantic vs. phonological) and 2 measures of verbal STM: (a) location of errors on the word pair repetition task and (b) imageability and frequency effects on the word pair repetition task. Results indicated that, as phonological word retrieval errors (relative to semantic) increase, bias toward correct repetition of high-imageability words increases.

CONCLUSIONS

Results suggest that word retrieval and verbal STM tasks likely rely on a partially shared temporary linguistic activation process.

What Matters in Semantic Feature Analysis: Practice-Related Predictors of Treatment Response in Aphasia

PURPOSE

This study investigated the predictive value of practice-related variables-number of treatment trials delivered, total treatment time, average number of trials per hour, and average number of participant-generated features per trial-in response to semantic feature analysis (SFA) treatment.

METHOD

SFA was administered to 17 participants with chronic aphasia daily for 4 weeks. Individualized treatment and semantically related probe lists were generated from items that participants were unable to name consistently during baseline testing. Treatment was administered to each list sequentially in a multiple-baseline design. Naming accuracy for treated and untreated items was obtained at study entry, exit, and 1-month follow-up.

RESULTS

Item-level naming accuracy was analyzed using logistic mixed-effect regression models. The average number of features generated per trial positively predicted naming accuracy for both treated and untreated items, at exit and follow-up. In contrast, total treatment time and average trials per hour did not significantly predict treatment response. The predictive effect of number of treatment trials on naming accuracy trended toward significance at exit, although this relationship held for treated items only.

CONCLUSIONS

These results suggest that the number of patient-generated features may be more strongly associated with SFA-related naming outcomes, particularly generalization and maintenance, than other practice-related variables.

SUPPLEMENTAL MATERIALS

https://doi.org/10.23641/asha.5734113.

Describing Phonological Paraphasias in Three Variants of Primary Progressive Aphasia

PURPOSE

The purpose of this study was to describe the linguistic environment of phonological paraphasias in 3 variants of primary progressive aphasia (semantic, logopenic, and nonfluent) and to describe the profiles of paraphasia production for each of these variants.

METHOD

Discourse samples of 26 individuals diagnosed with primary progressive aphasia were investigated for phonological paraphasias using the criteria established for the Philadelphia Naming Test (Moss Rehabilitation Research Institute, 2013). Phonological paraphasias were coded for paraphasia type, part of speech of the target word, target word frequency, type of segment in error, word position of consonant errors, type of error, and degree of change in consonant errors.

RESULTS

Eighteen individuals across the 3 variants produced phonological paraphasias. Most paraphasias were nonword, followed by formal, and then mixed, with errors primarily occurring on nouns and verbs, with relatively few on function words. Most errors were substitutions, followed by addition and deletion errors, and few sequencing errors. Errors were evenly distributed across vowels, consonant singletons, and clusters, with more errors occurring in initial and medial positions of words than in the final position of words. Most consonant errors consisted of only a single-feature change, with few 2- or 3-feature changes. Importantly, paraphasia productions by variant differed from these aggregate results, with unique production patterns for each variant.

CONCLUSIONS

These results suggest that a system where paraphasias are coded as present versus absent may be insufficient to adequately distinguish between the 3 subtypes of PPA. The 3 variants demonstrate patterns that may be used to improve phenotyping and diagnostic sensitivity. These results should be integrated with recent findings on phonological processing and speech rate. Future research should attempt to replicate these results in a larger sample of participants with longer speech samples and varied elicitation tasks.

SUPPLEMENTAL MATERIALS

https://doi.org/10.23641/asha.5558107.