The aim of this study was to investigate two factors that have been claimed to be associated with the word retrieval difficulties experienced by individuals with aphasia. These factors were aphasic subjects’ level of phonological awareness and their lexical semantic processing. (For complete abstract open document)

Verbal communication relies heavily on the ability to effortlessly produce intended words to express a meaning. This capacity is frequently impaired in individuals with aphasia, and impairment often lasts well into the chronic stages. However, the nature of anomia can vary. Phonological neighborhood density (PND) is one feature of words which has been shown to impact the ease of retrieval in speakers with aphasia; words with more similar-sounding neighbors are easier to retrieve because the neighbors help activate the target. However, it is unclear how different types of lexical access breakdowns affect the impact of PND. The aim of this project was to analyze the relationship between word retrieval accuracy, speech error patterns, and PND in individuals with aphasia. Twenty-two participants with various types and severities of aphasia named 200 single-syllable line drawings. WebFit, an online software program designed to fit naming data to a theoretical model of word retrieval, was used to characterize participants' error patterns by calculating the strength of connections within the lexicon, as well as the rate of decay. Analyses confirmed previous findings that participants with all types of breakdown achieved lower rates of overall accuracy. Weaker connections between semantic knowledge and words resulted in a more errors that were close to the target, relative to errors with no relationship to the target. Individuals with more severe impairments of the semantic-lexical connections and the lexical-phonological connections produced words with many neighbors more accurately than words with fewer neighbors. Implications for initial therapy target selection and directions for further research are discussed.

Although it is well established that persons with traumatic brain injury (TBI) experience word retrieval difficulties, the underlying cause of these deficits is not known. Difficulties with word retrieval have negative social implications as they can impact on the ability to converse with others. The overarching goal of this dissertation was to determine the underlying cause of problems with word retrieval after TBI. To test word retrieval in this dissertation, participants were given a series of word fluency tasks and the speed of word generation was measured. In addition to measuring interresponse times, procedures used by Rohrer, Wixted, Salmon and Butters (1995) were also followed. This involved the calculation of parameter estimates to investigate whether slowed retrieval or degraded semantic stores were responsible for the patients� word retrieval difficulties. One parameter (N) was a measure of the total number of retrievable words and the second parameter (tau) was an estimate of mean latency. Study 1 was designed to trial the procedure and equipment adopted throughout this dissertation to analyse speech. University students were presented with categories on a computer screen and asked to generate as many exemplars as possible in 60 seconds. A PowerLab Chart sound system was used to measure the time that each word was generated. The results of Study 1 showed that the methodology of previous research could be replicated using the PowerLab Chart sound system. In Study 2, persons with postconcussion syndrome (PCS) and matched controls were given two word fluency tasks. Results showed that on both tasks patients recalled fewer words, had longer pauses between words, and took significantly longer to generate their first word than controls. Also, patients had a significantly reduced N relative to controls, but there was no difference in tau between patients and controls. Given that the participants had not finished responding and that parameter estimates require responses to be exhausted, Study 3 was designed to replicate the findings of Study 2 using an extended recall period. In Study 3, patients with PCS and matched controls completed a series of word fluency tasks and were given extended periods of time to generate words. Results showed that the patients obtained significantly fewer words on two of the tasks, but no evidence of slowed retrieval was found. There was also no difference in the estimates of N and tau between patients and controls. As the patients in Study 3 sustained more minor injuries than those in Study 2, Study 4 tested patients with severe TBI. In Study 4, patients with severe TBI and matched controls were given a series of word fluency tasks. Results showed that the patients generated fewer words and experienced slowed retrieval. Again, there was no difference in the estimates of N and tau between patients and controls. The results of Study 4 confirmed the hypothesis that slowed word retrieval is a consequence of TBI. Taken together, the results of this dissertation show that an underlying slowness of processing is the primary cause of problems with word retrieval in persons with TBI.

Although it is well established that persons with traumatic brain injury (TBI) experience word retrieval difficulties, the underlying cause of these deficits is not known. Difficulties with word retrieval have negative social implications as they can impact on the ability to converse with others. The overarching goal of this dissertation was to determine the underlying cause of problems with word retrieval after TBI. To test word retrieval in this dissertation, participants were given a series of word fluency tasks and the speed of word generation was measured. In addition to measuring interresponse times, procedures used by Rohrer, Wixted, Salmon and Butters (1995) were also followed. This involved the calculation of parameter estimates to investigate whether slowed retrieval or degraded semantic stores were responsible for the patients� word retrieval difficulties. One parameter (N) was a measure of the total number of retrievable words and the second parameter (tau) was an estimate of mean latency. Study 1 was designed to trial the procedure and equipment adopted throughout this dissertation to analyse speech. University students were presented with categories on a computer screen and asked to generate as many exemplars as possible in 60 seconds. A PowerLab Chart sound system was used to measure the time that each word was generated. The results of Study 1 showed that the methodology of previous research could be replicated using the PowerLab Chart sound system. In Study 2, persons with postconcussion syndrome (PCS) and matched controls were given two word fluency tasks. Results showed that on both tasks patients recalled fewer words, had longer pauses between words, and took significantly longer to generate their first word than controls. Also, patients had a significantly reduced N relative to controls, but there was no difference in tau between patients and controls. Given that the participants had not finished responding and that parameter estimates require responses to be exhausted, Study 3 was designed to replicate the findings of Study 2 using an extended recall period. In Study 3, patients with PCS and matched controls completed a series of word fluency tasks and were given extended periods of time to generate words. Results showed that the patients obtained significantly fewer words on two of the tasks, but no evidence of slowed retrieval was found. There was also no difference in the estimates of N and tau between patients and controls. As the patients in Study 3 sustained more minor injuries than those in Study 2, Study 4 tested patients with severe TBI. In Study 4, patients with severe TBI and matched controls were given a series of word fluency tasks. Results showed that the patients generated fewer words and experienced slowed retrieval. Again, there was no difference in the estimates of N and tau between patients and controls. The results of Study 4 confirmed the hypothesis that slowed word retrieval is a consequence of TBI. Taken together, the results of this dissertation show that an underlying slowness of processing is the primary cause of problems with word retrieval in persons with TBI.

No description available.

The aims of this study were to determine if various treatment, item, and patient-level factors could be used to predict probe naming accuracy in a bilingual Spanish-English SFA treatment study. At the treatment-level, variables included phase (baseline vs. treatment), training condition (trained set 1 items vs. translations), and time (session). At the item-level, psycholinguistic variables were investigated including lexical frequency, phonological length in phones, and phonological neighborhood density. Finally, at the patient-level, impairment measures were used including aphasia severity (as measured by WAB AQ) naming impairment (represented by a composite naming score from pre-treatment assessments). Mixed-effects logistic regression methods were used to fit the data with fixed effects for the variables of interest as well as random effects for subject and item. The regression analyses revealed significant main effects of phase, time, and interactions with training condition such that naming accuracy on probes was higher for the treatment language during the treatment phase and over time in general. Significant effects were also noted for each of the psycholinguistic variables such that increased frequency, shorter length, and a larger neighborhood increased the likelihood of correct naming responses. Finally, overall aphasia severity and naming impairment both correlated with naming outcomes.

No description available.

No description available.

The purpose of this study was to examine the extent to which learning and recall are facilitated by semantic and phonological targets. A list-learning paradigm was administered to 10 individuals with a history of traumatic brain injury. Participants were asked to recall and identify words that were present on the list. The lists consisted of semantically related associate words and phonologically related associate words. Participants recalled significantly more semantically related associates than phonological associates. Demographic factors such as age, time-post injury, and educational attainment did not have a significant effect on the recall ability for either word target type. Word recognition ability also was not influenced by target type. The results of this study found adults with TBI use a semantic network following brain injury and that semantic targets are more beneficial for recall than phonological targets. / text

Sweden is getting an aging population and with this comes an increase in neurodegenerative diseases such as Alzheimer’s disease (AD). Bilingualism is also on the rise and this may result in an increase of bilingual people suffering from AD. Due to the linguistic deterioration associated with the illness people with AD, bilingual and monolingual, will be an increasing patient group with speech and language pathologists (SLPs). Word retrieval difficulty is an early symptom of the disease and several strategies to compensate for this have been observed (e.g. fillers, circumlocutions and semantic parafasias). The effectiveness of these strategies has not yet been established. With this background this study attempts to investigate which strategies are used by monolingual and bilingual people with AD to compensate for word retrieval difficulties. A case study was performed on four participants with AD, two of which were monolingual and two were bilingual. Spontaneous speech was collected by means of a semi-structured conversation and a short story was produced with picture support. The results showed that there were individual differences in terms of the compensatory strategies. The results indicated that the strategies’ effectiveness depended on the progression of the disease in each individual. No differences between the bilingual participants’ first and second language were observed with exception to the usage of code switching. The picture support seemed to be of some help for the participants to achieve better fluency of speech since word retrieval difficulties seemed to decrease. The conclusion is that SLPs could make their patients aware of several different strategies to compensate for word retrieval difficulties to discover what is the most effective for each individual; furthermore pictures can be used to help clients’ narratives. / Sverige får en allt äldre befolkning. Detta för med sig ökande antal personer med Alzheimers sjukdom (AD). Då sjukdomen innebär stor språklig påverkan kan denna patientgrupp förväntas öka inom den logopediska vården. Även andelen flerspråkiga i samhället växer, vilket gör att logopeder kommer att ta emot allt fler flerspråkiga äldre patienter. Ordmobiliseringssvårigheter har setts vara ett tidigt symtom vid sjukdomen både hos enspråkiga och flerspråkiga personer. Tidigare forskning har visat att ett flertal kompensatoriska strategier (t.ex. utfyllnader, omskrivningar och utbyten) används för att hantera dessa svårigheter men det är inte klarlagt hur väl dessa strategier fungerar. Därför undersöks i denna studie vilka kompensatoriska strategier som förekommer både hos enspråkiga och flerspråkiga personer med AD. En fallstudie genomfördes på fyra deltagare med AD, varav två enspråkiga och två flerspråkiga. Spontantal samlades in genom ett semistrukturerat samtal och en kortare berättelse genomfördes med hjälp av bildstöd. Resultaten visade att effektiviteten i de använda strategierna skiljer sig mellan individer. Hur långt deltagarna kommit i sjukdomsförloppet verkade dock ha betydelse. Ingen större skillnad mellan de flerspråkiga deltagarnas båda språk observerades förutom gällande användning av kodväxling. Deltagarna verkade i viss mån vara hjälpta av bildstöd för att uppnå bättre talflyt eftersom ordmobiliseringsproblematiken tycktes minska. Slutsatser som drogs är att logopeder kan medvetandegöra patienter och närstående om ett flertal olika strategier för att hitta den strategi som fungerar bäst för den individuella patienten samt att bildstöd kan användas för att underlätta berättande.