Effect of language proficiency and executive control on verbal fluency performance in bilinguals

We use a time-course analysis to examine the roles of vocabulary size and executive control in bilinguals’ verbal fluency performance. Two groups of bilinguals and a group of monolingual adults were tested in English with verbal fluency subtests from the Delis–Kaplan Executive Function System. The two bilingual groups were equivalent in their self-rated English proficiency but differed in levels of receptive and expressive vocabulary. We hypothesized that the difference between the two bilingual groups in vocabulary and between the monolingual and bilingual groups in executive control would lead to differences in performance on the category and letter fluency tests and dissociate the roles of vocabulary knowledge and executive control in verbal production. Bilinguals and monolinguals performed equivalently in category fluency, but the high-vocabulary bilingual group outperformed both monolinguals and low-vocabulary bilinguals in letter fluency. An analysis of the retrieval time-course functions in letter fluency showed dissociable effects of resources available at the initiation of the trial, considered to reflect vocabulary size, and ability to monitor and retrieve new items using a novel phonemic-based word searching strategy, considered to reflect executive control. The difference in slope of the best-fitting curves reflected enhanced executive control for both bilingual groups compared to monolinguals, whereas the difference in the starting point of the logarithmic functions reflected higher levels of vocabulary for high-vocabulary bilinguals and monolinguals compared to low-vocabulary bilinguals. The results are discussed in terms of the contributions of linguistic resources and executive control to verbal performance.     

Category size effects in semantic and letter fluency in Alzheimer's patients

Many studies have found that patients with Alzheimer's disease (AD) perform significantly worse than normal controls on verbal fluency tasks. Moreover, some studies have found that AD patients' deficits compared to controls are more severe for semantic fluency (e.g., vegetables) than for letter fluency (e.g. words that begin with F). These studies, however, have not taken category size into account. A comparison of AD patients and age-matched controls on three semantic and three letter categories revealed that both the size and type of a category significantly predicted AD patients' deficits on verbal fluency tasks. These results suggest that the verbal fluency of AD patients will be most attenuated on large semantic categories.     

The Genetic Association Between ADHD Symptoms and Reading Difficulties: The Role of Inattentiveness and IQ

Previous studies have documented the primarily genetic aetiology for the stronger phenotypic covariance between reading disability and ADHD inattention symptoms, compared to hyperactivity-impulsivity symptoms. In this study, we examined to what extent this covariation could be attributed to “generalist genes” shared with general cognitive ability or to “specialist” genes which may specifically underlie processes linking inattention symptoms and reading difficulties. We used multivariate structural equation modeling on IQ, parent and teacher ADHD ratings and parent ratings on reading difficulties from a general population sample of 1312 twins aged 7.9–10.9 years. The covariance between reading difficulties and ADHD inattention symptoms was largely driven by genetic (45%) and child-specific environment (21%) factors not shared with IQ and hyperactivity-impulsivity; only 11% of the covariance was due to genetic effects common with IQ. Aetiological influences shared among all phenotypes explained 47% of the variance in reading difficulties. The current study, using a general population sample, extends previous findings by showing, first, that the shared genetic variability between reading difficulties and ADHD inattention symptoms is largely independent from genes contributing to general cognitive ability and, second, that child-specific environment factors, independent from IQ, also contribute to the covariation between reading difficulties and inattention symptoms.     

Divergent thinking: Strategies and executive involvement in generating novel uses for familiar objects

Although the Alternative Uses divergent thinking task has been widely used in psychometric and experimental studies of creativity, the cognitive processes underlying this task have not been examined in detail before the two studies are reported here. In Experiment 1, a verbal protocol analysis study of the Alternative Uses task was carried out with a Think aloud group (N = 40) and a Silent control group (N = 64). The groups did not differ in fluency or novelty of idea production indicating no verbal overshadowing. Analysis of protocols from the Think aloud group suggested that initial responses were based on a strategy of Retrieval from long‐term memory of pre‐known uses. Later responses tended to be based on a small number of other strategies: property‐use generation, imagined Disassembly of the target object into components and scanning of Broad Use categories for possible uses of the target item. Novelty of uses was particularly associated with the Disassembly strategy. Experiment 2 (N = 103) addressed the role of executive processes in generating new and previously known uses by examining individual differences in category fluency, letter fluency and divergent task performance. After completing the task, participants were asked to indicate which of their responses were new for them. It was predicted and found in regression analyses that letter fluency (an executively loading task) was related to production of ‘new’ uses and category fluency was related to production of ‘old’ uses but not vice versa.     

Qualitative evaluation of divergent thinking in patients with schizophrenia

Patients with schizophrenia show deficits across a broad spectrum of neurocognitive domains. In particular, deficits in verbal fluency are common. Verbal fluency tests are neuropsychological tests that assess frontal lobe function or executive function but also assess divergent thinking. However, few studies have considered the impairment of verbal fluency from the viewpoint of divergent thinking. To consider the structure of divergent thinking, not only verbal assessments but also non-verbal assessments are indispensable. We administered several fluency tests, the idea fluency test, the design fluency test, and word (letter and category) fluency tests to 26 patients with schizophrenia and 26 healthy control subjects to evaluate divergent thinking in both groups and assessed their responses qualitatively. An acceptable minimal level of intelligence was maintained in the patient group. Although attention and executive functioning were relatively preserved in the subjects with schizophrenia, they demonstrated significant deficits in divergent thinking and had particular difficulty in producing ideas and designs requiring concept flexibility, a conversion of viewpoint, originality, or novelty. Research on deficits in divergent thinking in patients with schizophrenia may contribute to the development of cognitive and behavioral rehabilitation programs.     

Letter and Category Fluency in Normal Elderly Participants: a Population-Based Study

We studied variables influencing category and letter fluency in a large population-based sample of elderly participants. Letter and category fluency tasks were administered to 1133 unselected non-demented elderly participants in the Paquid cohort on normal and pathological aging. Age, education, principal lifetime occupation and depressive symptomatology independently influenced both category and letter fluency, while gender influenced only category fluency. A conceptualization measure (similarities) was found to influence fluency results mostly through education and prior occupation.     

Bilingualism and reading difficulties: an exploration in episodic and semantic memory

This study was designed to investigate the effect of bilingualism and reading difficulties (RD) on episodic and semantic memory. The subjects included 190 children (aged 9–12 years): 45 Iranian-Swedish bilinguals and 59 Swedish monolinguals with typically developed reading, along with 41 bilinguals and 45 monolinguals with RD. To measure episodic memory, subject-performed and verbal tasks were used for encoding, and both free and cued recall were used for retrieval. Letter and category fluency tasks were used to test semantic memory. In action memory, bilingual children with RD benefited less from enactment encoding form compared to children with typically developed reading. Additionally, bilingual with RD had lower rates of recollection in category fluency compared to their monolingual counterparts. However, in letter fluency, there was not found a difference between performances of bilinguals and monolinguals with RD. We discuss the involvement of long-term memory in both bilingualism and reading.     

Semantic and Phonemic Verbal Fluency in Blinds

A person who has suffered the total loss of a sensory system has, indirectly, suffered a brain lesion. Semantic and phonologic verbal fluency are used for evaluation of executive function and language. The aim of this study is evaluation and comparison of phonemic and semantic verbal fluency in acquired blinds. We compare 137 blinds and 124 sighted people in verbal fluency task. The tasks were phonemic and semantic verbal fluency test that subjects should be generate as many word as possible in a limited amount of time for a given letter (Phonemic fluency) or a given category (Semantic fluency). Independent T Test was used to comparing blind with sighted. Findings show significant difference between two groups so that that sighted subjects have higher performance in semantic verbal fluency task (p = 0.000). Comparing sighted and blind subjects in phonemic verbal fluency task shows performance in sighted subjects (p = 0.000). Based on this study blinds have lower performance in semantic and phonemic verbal fluency task as a executive function of frontal lobe.     

Verbal fluency output in children aged 7-16 as a function of the production criterion: qualitative analysis of clustering, switching processes, and semantic network exploitation

Developmental changes in children's verbal fluency were explored in this study. One hundred and forty children aged from 7 to 16 completed four verbal fluency tasks, each with a different the production criterion (letter, sound, semantic, and free). The age differences were analyzed both in terms of number of words produced, and clustering, switching, and semantic network exploration. Analysis of the number of words produced showed a larger difference between the 7-8- and the 9-10-year-olds in semantic than in letter fluency, but this difference gradually disappeared with increasing age for semantic fluency while remaining constant for letter fluency. In letter fluency production, age modified both the number of switches and clusters formed whereas in semantic fluency tasks, only cluster size changed with age. Concerning the semantic network exploration indicators derived from the supermarket fluency task, the number of categories sampled increased from 11 to 12 years, but efficient semantic exploitation occurred only after the age of 13-14 years. These results are discussed in terms of the development of strategic retrieval components and categorical knowledge.     

Executive dysfunction in a survival environment

Victims often respond to survival incidents with maladaptive behaviours that suggest impairment in executive function. To examine this hypothesis the authors tested sub‐components of executive function during an intensive military survival exercise. Compared to a control group the survival course participants showed significant impairment in the incongruent condition of the Stroop task; the mean repetition gap and adjacent letter pair components of the random letter generation task; and the planning and action components of the Tower of London task. No impairment was found in dual‐task performance nor in verbal fluency. The pattern of the data suggests that the maladaptive behaviour frequently observed in survival incidents may be explained by dysfunction in the supervisory system‐contention scheduler interface. Copyright © 2009 John Wiley & Sons, Ltd.     

Increased regional cerebral glucose metabolism and semantic memory performance in Alzheimer's disease: A pilot double blind transdermal nicotine positron emission tomography study

Nicotinic receptor dysfunction and impaired semantic memory occur early in Alzheimer's disease patients (AD). Previous research implied that nicotine's ability to enhance alertness, arousal, and cognition in a number of nonclinical populations was a function of its ability to stimulate CNS nicotinic cholinergic receptors. In this study it was hypothesized that transdermal administration of nicotine would increase both regional cerebral glucose metabolism (rCMRglc) and semantic memory (as assessed by verbal fluency). Two mild AD and two elderly controls underwent positron emission tomography scanning during a double blind nicotinic agonist verbal fluency challenge procedure. rCMRglc increases occurred in both AD patients, but not controls. In the two AD patients, verbal fluency scores increased by an average of 17%. One elderly control's verbal fluency increased, and the other decreased. These findings suggest that nicotine's effect on metabolism and verbal fluency is due to its ability to stimulate the cholinergic system.     

Cognitive correlates of mathematical achievement in children with cerebral palsy and typically developing children

Background . Remarkably few studies have investigated the nature and origin of learning difficulties in children with cerebral palsy (CP). Aims . To investigate math achievement in terms of word‐problem solving ability in children with CP and controls. Because of the potential importance of reading for word‐problem solving, we investigated reading as well. Sample . Children with CP attending either special (n= 41) or mainstream schools (n= 16) and a control group of typically developing children in mainstream schools (n= 16). Method . Group differences in third grade math and reading, controlled for IQ, were tested with analyses of co‐variance (ANCOVAs). Hierarchical regression was used to investigate cognitive correlates of third grade math and reading. Predictors included verbal and non‐verbal IQ measured in first grade, components of working memory (WM) and executive function (EF) measured in second grade, and arithmetic fact fluency and reading measured in third grade. Results . Children with CP in special schools performed significantly worse than their peers on word‐problem solving and reading. There was a trend towards worse performance in children with CP in mainstream schools compared to typically developing children. Conclusions . Impairments of non‐verbal IQ and WM updating predicted future difficulties in both word‐problem solving and reading. Impairments of visuospatial sketchpad and inhibition predicted future word‐problem, but not reading difficulty. Conversely, deficits of phonological loop predicted reading but not word‐problem difficulty. Concurrent arithmetic fact fluency and reading ability were both important for word‐problem solving ability. These results could potentially help to predict which children are likely to develop specific learning difficulties, facilitating early intervention.     

Differential impacts of age of acquisition on letter and semantic fluency in Alzheimer's disease patients and healthy older adults

The degree to which the typical age of acquisition (AoA) of words and word frequency have separable influences on verbal production tasks has been strongly debated. To examine the overlap between these factors in verbal fluency tasks, the performance of Alzheimer's disease (AD) patients (N = 34) and normal elderly controls (N = 36) was compared on semantic (e.g., vegetables) and letter (e.g., words that begin with F) fluency tasks. These comparisons revealed that words generated for the semantic fluency task had an earlier AoA while words generated for the letter fluency task had a higher word frequency. Differences in AoA between AD patients and controls were larger for semantic than letter fluency. These results suggest that AoA has an effect on verbal production that is independent of word frequency and that AoA has a semantic locus.     

Verbal fluency over time as a measure of automatic and controlled processing in children with ADHD

The performance of ADHD children on semantic category fluency (SCF) versus initial letter fluency (ILF) tasks was examined. For each participant, word production was recorded for each 15-s time slice on each task. Performance on both fluency tasks was compared to test the hypothesis that children with ADHD are characterized by a performance deficit on the ILF task because performance on this task is less automated than performance on the SCF. Children classified with ADHD (N = 20) were compared to children with other psychopathology (N = 118) and healthy controls (N = 130). Results indicated that the groups could not be differentiated by the total number of words produced in 60 s in either fluency task. As hypothesized, a significant interaction of group by productivity over time by type of fluency task was found: ADHD children had more problems finding words in the first 15 s of the IFL than did children in the other two groups, and as compared with their performance on the SCF. Results were taken to indicate that children with ADHD symptoms show a delay in the development of automating skills for processing abstract verbal information.     

The influence of learning style and cognitive ability on recall of names and faces in an older population

The present study examined whether, for older adults, a verbal or imagery cognitive style is associated with recall of names and faces learned in an experimental condition. Cognitive abilities that are represented in current models of face recognition and name recall were also examined. Those abilities included picture naming, verbal fluency (i.e., naming items within a given category), vocabulary comprehension, visual memory, and the learning of unassociated word pairs. Fifty older adults attempted to learn first and last names of 20 student actors and actresses pictured on videotapes (40 names total). On average, participants learned the most first names, followed by last names, and the fewest full names. The greater the number of responses on a questionnaire associated with an imagery cognitive style, the more the names of faces were correctly identified by participants. There was no significant relationship between a verbal cognitive style and the number of names and faces recalled. As for cognitive abilities, all of the abilities measured--with the exception of vocabulary comprehension--were significantly associated with the number of names and faces learned. A regression analysis indicated that the best predictor of successful name-face learning was the participants' ability to learn and recall 5 unrelated word pairs. When that cognitive measure was deleted from the regression analysis, delayed visual memory and verbal fluency were the next best predictors of the older adults' ability to learn names and faces.     

Task orientation, parental warmth and SES account for a significant proportion of the shared environmental variance in general cognitive ability in early childhood: evidence from a twin study

Prior research suggests shared environmental influences on cognitive performance are important in early childhood. However, few studies have attempted to identify the factors comprising this shared environmental variance. To address this issue, we examined the covariance between task orientation, parental warmth, socioeconomic status and general cognitive ability in a British twin study of 125 pairs of identical and same-sex fraternal twins. Task orientation correlated r =.41 with general cognitive ability Bivariate genetic analyses suggested that this correlation was mediated by shared environmental influences. Additional analyses suggested that SES and parental warmth mediated about two-thirds of the shared environmental covariance between task engagement and cognitive skills.     

Word fluency performance and strategies in children with cochlear implants: age‐dependent effects?

Löfkvist, U., Almkvist, O., Lyxell, B. & Tallberg, I.‐M. (2012). Word fluency performance and strategies in children with cochlear implants: age‐dependent effects? Scandinavian Journal of Psychology 53, 467–474. Word fluency was examined in 73 Swedish children aged 6–9 years divided into two age groups, 6–7 and 8–9 years; 34 deaf children with cochlear implants (CI) (15 girls/19 boys) and 39 age‐matched children with normal hearing (NH) (20 girls/19 boys). One purpose was to compare the ability to retrieve words in two different word fluency tasks; one phonemically based (FAS letter fluency) and one semantically based (animal fluency). A second purpose was to examine retrieval strategies in the two tasks by conducting an analysis of clustering and switching of word sequences. In general we found that age was an important factor for word fluency ability, in both the CI and the NH groups. It was also demonstrated that children with CI aged 8–9 years retrieved significantly fewer words and used less efficient strategies in the retrieval process, especially on the phonemically based task compared to children with NH of the same ages, whereas children 6–7 years performed similarly in both groups regarding number of retrieved words and use of strategies. The results are discussed with respect to factors such as age differences in performance for children with CI, especially for the phonemically based task.     

Disordered gambling as defined by the Diagnostic and Statistical Manual of Mental Disorders and the South Oaks Gambling Screen: evidence for a common etiologic structure

In a previous article, we demonstrated in a large twin study that disordered gambling (DG), as defined by the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV), ran in families, that about half of the variation in liability for DG was due to familial factors, and that all of this was explained by shared genetic rather than shared environmental influences (Slutske, Zhu, Meier, & Martin, 2010). The purpose of the present study is to extend this work to include an alternative conceptualization of DG that is provided by the South Oaks Gambling Screen (SOGS) item set in order to (a) compare the magnitude of the familial resemblance obtained when using the two definitions of DG (based on the DSM-IV and the SOGS), (b) examine the extent to which the 2 definitions tap the same underlying sources of genetic and environmental variation, and (c) examine whether the same results will be obtained among men and women. The results of bivariate twin model-fitting analyses suggested that DG, as defined by the DSM-IV and the SOGS, substantially overlapped at the etiologic level among both men and women, which supports the construct validity of both the DSM and the SOGS conceptualizations of DG. This study highlights the utility of twin studies for appraising the validity of the diagnostic nomenclature.     

Contributions of processing ability and knowledge to verbal memory tasks across the adult life-span

This study investigated the relationships of processing capacity and knowledge to memory measures that varied in retrieval difficulty and reliance on verbal knowledge in an adult life-span sample (N = 341). It was hypothesized that processing ability (speed and working memory) would have the strongest relationship to tasks requiring active retrieval and that knowledge (vocabulary ability) would be related to verbal fluency and cued recall, as participants relied upon verbal knowledge to retrieve category items (fluency) or develop associations (cued recall). Measurement and structural equation models were developed for the entire sample and separately for younger (aged 20-54 years, n = 168) and older (aged 55-92 years, n = 173) subgroups. In accordance with the hypotheses, processing ability was found to be most highly related to free recall, with additional significant relationships to cued recall, verbal fluency, and recognition. Knowledge was found to be significantly related only to verbal fluency and to cued recall. Moreover, knowledge was more important for older than for younger adults in mediating variance in cued recall, suggesting that older adults may use age-related increases in knowledge to partially compensate for processing declines when environmental support is available in memory tasks.     

Differential impacts of age of acquisition on letter and semantic fluency in Alzheimer's disease patients and healthy older adults

The degree to which the typical age of acquisition (AoA) of words and word frequency have separable influences on verbal production tasks has been strongly debated. To examine the overlap between these factors in verbal fluency tasks, the performance of Alzheimer's disease (AD) patients (N?=?34) and normal elderly controls (N?=?36) was compared on semantic (e.g., vegetables) and letter (e.g., words that begin with F) fluency tasks. These comparisons revealed that words generated for the semantic fluency task had an earlier AoA while words generated for the letter fluency task had a higher word frequency. Differences in AoA between AD patients and controls were larger for semantic than letter fluency. These results suggest that AoA has an effect on verbal production that is independent of word frequency and that AoA has a semantic locus.