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Phonological and semantic verbal fluency test: Scoring criteria and normative data for clustering and switching strategies for Colombian children and adolescents
Abstract
Background:
Verbal fluency tests (VFT) are highly sensitive to cognitive deficits. Usually, the score on VFT is based on the number of correct words produced, yet it alone gives little information regarding underlying test performance. The implementation of different strategies (cluster and switching) to perform efficiently during the tasks provide more valuable information. However, normative data for clustering and switching strategies are scarce. Moreover, scoring criteria adapted to Colombian Spanish are missing.
Aims:
(1) To describe the Colombian adaptation of the scoring system guidelines for clustering and switching strategies in VFT; (2) to determine its reliability; and (3) to provide normative data for Colombian children and adolescents aged 6-17 years.
Methods & procedures:
A total of 691 children and adolescents from Colombia completed phonological (/f/, /a/, /s/, /m/, /r/ and /p/) and semantic (animals and fruits) VFT, and five scores were calculated: total score (TS), number of clusters (NC), cluster size (CS), mean cluster size (MCS) and number of switches (NS). The intraclass correlation coefficient was used for interrater reliability. Hierarchical multiple regressions were conducted to investigate which strategies were associated with VFT TS. Multiple regressions were conducted for each strategy, including as predictors age, age2 , sex, mean parents' education (MPE), MPE2 and type of school, to generate normative data.
Outcomes & results:
Reliability indexes were excellent. Age was associated with VFT TS, but weakly compared with strategies. For both VFT TS, NS was the strongest variable, followed by CS and NC. Regarding norms, age was the strongest predictor for all measures, while age2 was relevant for NC (/f/ phoneme) and NS (/m/ phoneme). Participants with higher MPE obtained more NC, and NS, and larger CS in several phonemes and categories. Children and adolescents from private school generated more NC, NS and larger CS in /s/ phoneme.
Conclusions & implications:
This study provides new scoring guidelines and normative data for clustering and switching strategies for Colombian children and adolescents between 6 and 17 years old. Clinical neuropsychologists should include these measures as part of their everyday practice.
What this paper adds:
What is already known on the subject VFT are widely used within the paediatric population due to its sensitivity to brain injury. Its score is based on the number of correct words produced; however, TS alone gives little information regarding underlying test performance. Several normative data for VFT TS in the paediatric population exist, but normative data for clustering and switching strategies are scarce. What this paper adds to existing knowledge The present study is the first to describe the Colombian adaptation of the scoring guidelines for clustering and switching strategies, and provided normative data for these strategies for children and adolescents between 6 and 17 years old. What are the potential or actual clinical implications of this work? Knowing VFT's performance, including strategy development and use in healthy children and adolescents, may be useful for clinical settings. We encourage clinicians to include not only TS, but also a careful analysis of strategies that may be more informative of the underlying cognitive processes failure than TS.
Background
The category Fluency Test (CFT) is included in the MATRICS consensus cognitive battery for schizophrenia (MCCB). This test has several components that allow the exploration of other cognitive functions and could be related to different symptom profiles.
Methods
a sample of 98 Mexican adolescents was evaluated with the CFT and the following components were analyzed: total words, errors, clusters, switching, related words, and categories. Demographic and clinical differences among them and correlations with other MCCB tests and with Positive and Negative Syndrome Scale (PANSS) factors were explored.
Results
The CFT components showed significant correlations with each other and with other MCCB tests, particularly with those related to verbal learning, working memory, and speed of processing. In addition, they showed moderate correlations with the total PANSS score and with the negative, positive, and cognitive PANSS factors.
Conclusions
The analysis of CFT components allows clinicians and investigators to obtain information regarding other cognitive functions and symptom profiles in adolescents with schizophrenia.
Performance in semantic verbal fluency (SVF) tasks, mainly measured by the number of words of a particular semantic category produced within a limited time, is a widely accepted measure of cognitive functioning used in the neuropsychological assessment of children and adults. Two strategic processes, Clustering and Switching (C&S) have been proposed to underlie fluency processes and affect performance in the task. However, few studies have reported on the development of those cognitive strategies and their relationship with word productivity in typically developing children. Even fewer studies have covered a broad developmental period from preschool to adolescence or measured the effect of contextual factors in this relationship. Based on a sample of 472 typically developing Greek-speaking children aged 4;0 to 16;11 years, we investigated the development of SVF performance and reported on the degree to which it is affected by C&S strategies, children’s sex, and level of parental education. Results revealed a large effect of age on word productivity and on the use of C&S strategies. Two switching factors (number of clusters and number of switches) and two clustering factors (mean cluster size and a novel measure, maximum cluster size), appeared to be significantly associated with word productivity, with the largest effect being attributed to the two switching factors. C&S factors, together with children’s age and parental education, predicted 91.7% of the variance in the SVF score. Children’s sex was not found to have a significant effect on either word productivity or C&S strategies. Results are discussed for their theoretical implications on the strategic processes underlying word production in typically developing children.
Although verbal fluency is a frequently used neuropsychological test, little is known about the underlying cognitive processes. The authors proposed that 2 important components of fluency performance are clustering (i.e., the production of words within semantic or phonemic subcategories) and switching (i.e., the ability to shift between clusters). In Experiment 1, correlational data from 54 older and 41 younger adults indicated that both components were highly correlated with the number of words generated on semantic fluency, whereas switching was more highly correlated than clustering with the number of words generated on phonemic fluency. On semantic fluency, younger participants generated more words and switched more frequently than older participants; on phonemic fluency, older participants produced larger clusters than younger participants. In Experiment 2, among 22 young adults, divided attention decreased the number of words generated and decreased switching on phonemic fluency only. Overall, findings suggest that clustering and switching are dissociable fluency components and that switching is related to frontal-lobe functioning.
Expressive language delays and executive functioning challenges are common in youth with Down syndrome (DS). Verbal fluency is one method to investigate these constructs. We examined semantic verbal fluency responses to determine patterns in response generation and the psychometric properties of coded cluster formations. Participants were 97 children and adolescents with DS ranging in age from 6 to 19 years old. The semantic verbal fluency task was administered at two time points, two weeks apart. Heterogeneity in performance was observed for responses when coded either with conventional or contextual classifications. Overall, the number of switches in conventional classifications was greater than contextual classifications. This implies that participants did not use traditional (conventional) categories to organize their semantic verbal fluency responses, but may have been using contextual strategies. However, the number of switches and cluster size variables had poor to moderate test–retest reliability, which indicated that participants did not stay consistent with their performance over the two-week testing interval, regardless of the strategies used. Therefore, conventional and contextual clusters and switches as a measure of executive control may not be appropriate for all individuals with DS and additional attention is warranted to determine the utility of response coding in this population.
La tarea de fluidez verbal (FV) es una medida de la flexibilidad cognitiva y la estrategia de búsqueda dentro del léxico y el tema semántico. En este trabajo, se probó el uso de estrategias organizativas, es decir, agrupación y cambio en la fluidez semántica y fonológica en niños españoles sanos divididos en dos grupos: el grupo 1 de niños más pequeños (de 8 a 9 años) y el grupo 2 de niños mayores (de 10 años de edad) –11) introducción de diferentes letras (F, A, S y P, M, R) y categorías semánticas (animales y comidas o bebidas). La fluidez semántica fue mayor que la fluidez fonológica en ambos grupos de edad. Además, los niños mayores mostraron un mejor desempeño de ambas fluencias que los niños más pequeños específicamente para el grupo de letras FAS, la letra M y todas las categorías semánticas utilizadas. A partir de los análisis fonológicos, los niños más pequeños evocaron más palabras con el grupo de letras PMR que con el grupo FAS. Además, solo se observó una mejora en la fluidez semántica asociada con la categoría del animal frente a las comidas y bebidas en el grupo de niños más pequeños. Con respecto a las estrategias organizativas, los niños mayores usaron más interruptores específicamente en el grupo FAS y más grupos para la categoría de comidas o bebidas en comparación con el grupo de niños mayores. Para finalizar, las relaciones entre el número de palabras evocadas y el número de clústeres y conmutadores para ambas tareas de FV fueron significativas y positivas. Estos datos sugieren que el tipo de letra y la categoría semántica empleada en la evaluación de FV modulan el rendimiento de fluidez verbal en ambos grupos de edad.
The verbal fluency (VF) task is a measure of cognitive flexibility and search strategy within the lexicon and semantic topic. In this work the use of organizational strategies, i.e., clustering and switching in semantic and phonological fluency was tested in healthy Spanish children divided in two groups: group 1 of younger children (age 8–9) and group 2 of older children (age 10–11) introducing different letters (F, A, S and P, M, R) and semantic categories (animals and meals or drinks). Semantic fluency was greater than phonological fluency in both age groups. In addition, older children showed better performance of both fluencies than younger children specifically for FAS letters group, M letter and all of semantic categories used. From the phonological analyses, younger children evoked more word with the PMR letter group than with the FAS one. Moreover, an improvement of semantic fluency associated with the animal’s category faced to meals and drink was observed only in the younger children group. In respect to organizational strategies, older children used more switches specifically in FAS group and more clusters for the meals or drinks category compared with the older children group. To finish, the relationships between the number of words evoked and the number of clusters and switches for both VF tasks were significant and positive. These data suggest that the type of letter and the semantic category employed in the VF evaluation modulate the verbal fluency performance in both groups of age
To prevent mistakes in psychological assessment, the precision of test norms is important. This can be achieved by drawing a large normative sample and using regression-based norming. Based on that norming method, a procedure for sample size planning to make inference on Z-scores and percentile rank scores is proposed. Sampling variance formulas for these norm statistics are derived and used to obtain the optimal design, that is, the optimal predictor distribution, for the normative sample, thereby maximizing precision of estimation. This is done under five regression models with a quantitative and a categorical predictor, differing in whether they allow for interaction and nonlinearity. Efficient robust designs are given in case of uncertainty about the regression model. Furthermore, formulas are provided to compute the normative sample size such that individuals' positions relative to the derived norms can be assessed with prespecified power and precision. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
Supplemental materials:
doi.org/10.1037/met0000394.supp and
github.com/FrancescoInnocenti-Stat/SampSize-OD-Norming
Background: Verbal fluency (VF) has been associated with several cognitive functions, but the cognitive processes underlying verbal fluency deficits in Multiple Sclerosis (MS) are controversial. Further knowledge about VF could be useful in clinical practice, because these tasks are brief, applicable, and reliable in MS patients. In this study, we aimed to evaluate the cognitive processes related to VF and to develop machine-learning algorithms to predict those patients with cognitive deficits using only VF-derived scores.
Methods: Two hundred participants with MS were enrolled and examined using a comprehensive neuropsychological battery, including semantic and phonemic fluencies. Automatic linear modeling was used to identify the neuropsychological test predictors of VF scores. Furthermore, machine-learning algorithms (support vector machines, random forest) were developed to predict those patients with cognitive deficits using only VF-derived scores.
Results: Neuropsychological tests associated with attention-executive functioning, memory, and language were the main predictors of the different fluency scores. However, the importance of memory was greater in semantic fluency and clustering scores, and executive functioning in phonemic fluency and switching. Machine learning algorithms predicted general cognitive impairment and executive dysfunction, with F1-scores over 67–71%.
Conclusions: VF was influenced by many other cognitive processes, mainly including attention-executive functioning, episodic memory, and language. Semantic fluency and clustering were more explained by memory function, while phonemic fluency and switching were more related to executive functioning. Our study supports that the multiple cognitive components underlying VF tasks in MS could serve for screening purposes and the detection of executive dysfunction.
In the wake of limited knowledge on verbal fluency performance in typically developing children, the present study aims at investigating the semantic fluency performance of Malayalam speaking children across age, gender and tasks. Using a cross-sectional study design, semantic fluency performance (on food and vehicle fluency tasks) was investigated in 1015 Malayalam speaking typically developing children aged 5 to 15 years. The findings revealed the positive influence of age and task with no substantial difference between gender groups, with good inter-rater and intra-rater reliability. The study outcomes depicted a distinct pattern of continuous and linear developmental trend in organizational strategies, with no specific age band showing any dramatic increase in performance. Semantic fluency as a task has great potential within the developmental context for understanding the highly language, culture, and task based word retrieval mechanism.
Objective:
To generate normative data for the phonological and semantic verbal fluency tests (VFT) in Spanish-speaking pediatric populations.
Method:
The sample consisted of 4,373 healthy children from nine countries in Latin America (Chile, Cuba, Ecuador, Guatemala, Honduras, Mexico, Paraguay, Peru, and Puerto Rico) and Spain. Each participant was administered the VFT as part of a larger neuropsychological battery. Scores for letters F, A, S, and animals and fruit categories were normed using multiple linear regressions and standard deviations of residual values. Age, age2, sex, and mean level of parental education (MLPE) were included as predictors in the analyses.
Results:
The final multiple linear regression models showed main effects for age on all scores, such that scores increased linearly as a function of age. Age2 had a significant effect in Chile (animals), Cuba (A letter, fruits), Ecuador (animals, fruits), Guatemala (S letter), Honduras (F letter), Mexico (animals, fruits), Paraguay (F letter), Peru (fruits), and Spain (F, S letters, animals, fruits). Models showed an effect for MLPE in Chile (F, A letters, animals, fruits), Ecuador (S letter, animals, fruits), Guatelama (S letter, animals), Honduras (animals), Mexico (F, A, S letters, animals, fruits), Paraguay (A letter, animals, fruits), Puerto Rico (A, S letters, animals), and Spain (all scores). Sex scores were found significant in Chile (animals), Ecuador (A letter, fruits), Guatemala (fruits), Mexico (F letter, fruits), Paraguay (F, A, S letters, fruits), Puerto Rico (F letter, animals, fruits), and Spain (F letter, fruits).
Conclusions:
This is the largest multi-national Spanish speaking pediatric normative study in the world, and as such it will allow neuropsychologists from these countries to have a more accurate way to interpret the phonological and semantic VFT in pediatric populations.
We investigated the role of age and school type on clustering and switching in verbal fluency tasks (VFTs) with Brazilian children. The children were administered unconstrained, phonemic and semantic VFTs with a duration of 150 or 120 s, respectively. Both age and school type influenced all variables and in terms of performance over time. Older children and private school students outperformed the remainder of the sample, with the first 30 s of each VFT usually being the most productive. Although the size of the clusters produced did not differ between groups, the types of clusters did show some variations, with semantic clusters being the most frequent. Our results revealed strong correlations between switching ability and word production in all three VFTs. In conclusion, the executive functions known as planning and cognitive flexibility play a crucial role in word production by organising and facilitating the recall of lexical information from memory.
The objective of this study was to describe an adaptation to Brazilian Portuguese of the methodological criteria for analysis of clustering and switching in semantic verbal fluency (SVF) and phonemic verbal fluency (PVF) tasks. The adaptation process consisted of six steps, including the selection of the clustering and switching variables based on data from a sample of 419 children and the analysis of inter-rater reliability (six raters). The following variables were scored: the total number of words generated the raw number of clusters, the mean cluster size, and the raw number of switches. There was a significant association between raters (intra-class correlation coefficients between 0.95 and 0.99), showing that the analytical method was reliable. Our study provides an evaluation of SVF and PVF tasks that goes beyond the overall score, making it possible to investigate the cognitive processes underlying this neuropsychological function.
We administered a semantic verbal fluency (SVF) task to two groups of children (age range from 5 to 8): 47 diagnosed with Autism Spectrum Disorder (ASD Group) and 53 with typical development (Comparison Group), matched on gender, chronological age, and non-verbal IQ. Four specific indexes were calculated from the SVF task, reflecting the different underlying cognitive strategies used: clustering (component of generativity and lexical-semantic access), and switching (executive component, cognitive flexibility). First, we compared the performance of the two groups on the different SVF task indicators, with the ASD group scoring lower than the Comparison Group, although the difference was greater on switching than on clustering. Second, we analyzed the relationships between the different SVF measures and chronological age, verbal IQ and non-verbal IQ. While in the Comparison Group chronological age was the main predictor of performance on the SVF task, in the ASD Group verbal IQ was the best predictor. In the children with ASD, therefore, greater linguistic competence would be associated with better performance on the SVF task, which should be taken into account in speech therapies designed to achieve improvements in linguistic generativity and cognitive flexibility.
This work presents normative data for Brazilian children on the Rey Auditory Verbal Learning Test (RAVLT), Verbal Fluency Test (VFT), and Stroop test (ST). The effects of age were evaluated. The patterns of results were compared with the literature, and validity was assessed using cluster analysis. The participants included 390 healthy subjects, 7–14 years old. Mixed-model analyses of variance were performed, with age as the between-subjects factor and test phase, trial, and stimulus type as the within-subjects factors. A cluster analysis explored the classification of the cognitive variables. Older children performed better than younger children, with differences in learning scores on the VFT and RALVT between children who were 7–8 and 11–12 years old and differences in Stroop times between children who were 9–10 and 11–12 years old. Letter fluency was easier than semantic fluency, with no interaction between type of fluency and age. Stroop times and errors increased as interference increased and decreased as age increased. Age differences in total learning, proactive interference, and forgetting were observed for the RAVLT. The cluster analysis revealed 2 groups: ST variables (attention) and RAVLT and VFT variables (memory). Some differences in terms of absolute scores were found compared with other Brazilian studies, but the results showed internal consistency and a pattern of results similar to the published data. The dissociation between the memory and attention cognitive domains and the pattern of subgroups in the cluster analysis were consistent with the cognitive neuropsychology literature, providing further evidence of the validity of the paradigms.
Background: This article aims to assess the linguistic functioning in terms of phonological and semantic verbal fluency in people with dyslexia, when compared to those without dyslexia. Material/Methods: We examined, qualitatively and quantitatively, the preferred performance strategies, depending on specific learning difficulties and the criterion used, of 28 (53%) high school students with dyslexia and 25 (47%) without, who participated in our study. Results: No intergroup differences in the phonological and semantic verbal fluency in the number of words produced were found; the semantic task turned out to be easier, and was performed faster, than the phonological task, for all participants, regardless of dyslexia. However, in the criterion group the performance in the phonological fluency task was affected by the selected sound. This result suggests that it is especially difficult for Polish students with dyslexia to differentiate between the representation of a sound and a letter. For the semantic fluency, we found that working memory was related to word production in the criterion group, but not in the control group. Since both working and long-term memory deficits have been reported in people with dyslexia, this suggests the inefficient verbal compensatory cognitive abilities used by this group. Word production turned out to be a relative strength of students with dyslexia, as they performed on a level with their non-dyslexic peers, while employing mostly similar strategies. Conclusions: Subtle differences between the strategies employed by students with and without dyslexia in phonological and semantic verbal fluency seemed to be related to the phonological and memory deficits of the participants with dyslexia; yet these did not influence task performance efficiency.
Este estudio tuvo como objetivo analizar la fluidez verbal (FV) según tipo de tarea (semántica vs. fonológica), intervalo de tiempo (1-15seg. vs. 16-30seg. vs. 31-45seg. vs. 46-60seg.) y estrato socioeconómico (medio vs. bajo) en niños escolarizados. Se trabajó con una muestra de 248 niños de 8 a 12 años de edad de diferentes estratos socioeconómicos (ESE). Se administraron el test de FV semántica (FVS) y fonológica (FVF) y otras pruebas cognitivas para evaluar posibles asociaciones. Los resultados indicaron diferencias significativas según el ESE en el número total de palabras generadas en ambos tipos de FV y en función del tiempo. Los niños de estrato socioeconómico bajo presentaron más dificultades para generar palabras en la FVF y a partir de los 16 segundos en donde se ponen en juego los procesos controlados. Se analizó además la relación entre diferentes variables socioeconómicas y la FV y se encontró que el nivel de instrucción de la madre fue el único predictor significativo. Finalmente, los resultados revelaron que el lenguaje, la inteligencia y otras funciones ejecutivas predicen la FV aunque con diferencias según el tipo de tarea semántica o fonológica. Se discuten los resultados en función de la utilidad de la tarea como medida del procesamiento cognitivo y del impacto que tiene el ESE sobre el procesamiento controlado y el funcionamiento ejecutivo
The processing of verbal fluency tasks relies on the coordinated activity of a number of brain areas, particularly in the frontal and temporal lobes of the left hemisphere. Recent studies using functional magnetic resonance imaging (fMRI) to study the neural networks subserving verbal fluency functions have yielded divergent results especially with respect to a parcellation of the inferior frontal gyrus for phonemic and semantic verbal fluency. We conducted a coordinate-based activation likelihood estimation (ALE) meta-analysis on brain activation during the processing of phonemic and semantic verbal fluency tasks involving 28 individual studies with 490 healthy volunteers.
For phonemic as well as for semantic verbal fluency, the most prominent clusters of brain activation were found in the left inferior/middle frontal gyrus (LIFG/MIFG) and the anterior cingulate gyrus. BA 44 was only involved in the processing of phonemic verbal fluency tasks, BA 45 and 47 in the processing of phonemic and semantic fluency tasks.
Our comparison of brain activation during the execution of either phonemic or semantic verbal fluency tasks revealed evidence for spatially different activation in BA 44, but not other regions of the LIFG/LMFG (BA 9, 45, 47) during phonemic and semantic verbal fluency processing.
This review was aimed at systematically in-vestigating the evidence suggesting that obese individ-uals demonstrate impaired performance on behavioural tasks examining executive functioning abilities. A sys-tematic review of literature was carried out by search-ing five separate databases (PsycINFO, MEDLINE, EMBASE, CINAHL and PubMed) and a hand search of relevant journals. Twenty-one empirical papers were identified from the search criteria and the results were considered in relation to different executive functioning domains. There is little consistency of results both within and across different domains of executive func-tioning. The review suggests that obese individuals show difficulties with decision-making, planning and problem-solving when compared to healthy weight con-trols, with fewer difficulties reported on tasks examin-ing verbal fluency and learning and memory. A lack of replication and underreporting of descriptive data is a key limitation of studies in this area and further re-search is needed to examine the mechanisms underpin-ning the relationship between obesity and executive functioning.
This study investigated 3 broad classes of individual-differences variables (job-search motives, competencies, and constraints) as predictors of job-search intensity among 292 unemployed job seekers. Also assessed was the relationship between job-search intensity and reemployment success in a longitudinal context. Results show significant relationships between the predictors employment commitment, financial hardship, job-search self-efficacy, and motivation control and the outcome job-search intensity. Support was not found for a relationship between perceived job-search constraints and job-search intensity. Motivation control was highlighted as the only lagged predictor of job-search intensity over time for those who were continuously unemployed. Job-search intensity predicted Time 2 reemployment status for the sample as a whole, but not reemployment quality for those who found jobs over the study's duration. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The Animal Verbal Fluency (AVF) and Design Fluency (DF) structured and unstructured test versions were administered to N = 294 healthy native Dutch-speaking children who were aged between 6.56 and 15.85 years. The AVF and DF structured test scores increased linearly as a function of age, whilst the relation between age and the DF unstructured test score was curvilinear (i.e., the improvement in test scores was much more pronounced for younger children than for older children). A higher mean level of parental education was associated with significantly higher AVF and DF structured test scores. Sex was not associated with any of the outcomes. Demographically corrected norms for the AVF and DF tests were established, and an automatic scoring program was provided.
Very few normative data on psychometric tests are available in sub-Saharan African countries, in spite of the obvious needs and potential benefits from psychological and neuropsychological examination in these contexts. The goal of the ongoing overall project is to assess the cognitive functioning of Cameroonian school-aged children suffering from Sickle Cell Disease. For this purpose, normative data on psychometric tests adapted to the Cameroonian cultural context had to first be established.
125 "healthy" school-aged Cameroonian children were recruited from public schools in the city of Yaounde and were given a battery of 14 cognitive tests assessing executive functions and memory. Criteria for tests inclusions were: simplicity of administration, few verbal demand, and broad cross-cultural applicability. Results allow concluding that the battery is appropriate for neuropsychological evaluation in Cameroon, with the exception of the Block Design test (WISC-IV) and a Verbal Phonemic Fluency test. A factor analysis shows a division of the tests in a four-factors model that is very consistent with the expected measures of the tests. Effects of gender, age, and education are also discussed.
this study is the first to report normative data on neuropsychological tests among children in Cameroon and constitutes an initial step for the advancement of neuropsychology in this country in particular and in sub-Saharan Africa in general. The battery is currently used in Cameroon with children suffering from Sickle Cell Disease as an aid to detect cerebrovascular complications.
Although verbal fluency is a frequently used neuropsychological test, little is known about the underlying cognitive processes. The authors proposed that 2 important components of fluency performance are clustering (i.e., the production of words within semantic or phonemic subcategories) and switching (i.e., the ability to shift between clusters). In Experiment 1, correlational data from 54 older and 41 younger adults indicated that both components were highly correlated with the number of words generated on semantic fluency, whereas switching was more highly correlated than clustering with the number of words generated on phonemic fluency. On semantic fluency, younger participants generated more words and switched more frequently than older participants; on phonemic fluency, older participants produced larger clusters than younger participants. In Experiment 2, among 22 young adults, divided attention decreased the number of words generated and decreased switching on phonemic fluency only. Overall, findings suggest that clustering and switching are dissociable fluency components and that switching is related to frontal-lobe functioning.
This study used a dual-task interference paradigm to test the hypothesis that different subcomponents of working memory differentially contribute to performance on letter fluency and category fluency tasks. College students (N = 96) performed each type of verbal fluency task in isolation and concurrently with I of 3 secondary tasks. The secondary tasks were chosen for their putative involvement in different working memory subcomponents. Two subsystems of working memory, the phonological loop and the visuospatial sketchpad, were identified as important contributors to fluency performance, especially to performance on letter fluency and category fluency tasks, respectively. Moreover, the results also suggest that the executive function, mental set shifting, may be deployed to perform both letter fluency and category fluency tasks.
This study is part of a larger project to generate norms for letter verbal fluency test (VFT) in 3,284 children from nine Latin American countries. The letter VFT (letters M, R, and P) was administered and multiple linear regressions, including age, age ² , MPE (mean parental education), MPE ² , sex, and interactions were used as predictors. Results showed significant differences across countries for all scores. Age affected scores linearly except for Ecuador (P-letter), in which a quadratic effect was found. Scores increased linearly as a function of MPE, with the exception of Mexico (R-letter), in which a quadratic effect was found. Age by MPE (M- and P-letters), and age by MPE ² (R-letter) interactions were found in Mexico. Sex had an impact on letter R in Cuba, and letter P in Ecuador and Paraguay. Age ² by sex interaction was found in Ecuador (P-letter). These norms will be useful for clinical neuropsychologists in these countries to evaluate their patients’ verbal fluency.
Purpose
The aim of this study was to compare Basque and Catalan bilinguals' performance on the letter verbal fluency test and determine whether significant differences are present depending on the letters used and the language of administration.
Method
The sample consisted of 87 Spanish monolinguals, 139 Basque bilinguals, and 130 Catalan bilinguals from Spain. Participants completed the letter verbal fluency test using the letters F, A, S, M, R, P, and E.
Results
Bilinguals scored higher on the letter verbal fluency test when they were tested in Spanish than in Basque or Catalan. No performance differences were found according to native language or dialects within Basque participants. Catalans with Spanish as their native language scored lower on the letter F compared to those who grew up speaking Catalan and Spanish. The suggested letters to use with Basque speakers are A, E, and B; the suggested letters to use with Catalan speakers are P, F, and M; and the suggested letters to use with Spanish speakers are M, R, and P.
Conclusion
Selecting appropriate stimuli depending on the language of testing is the first crucial step to assess verbal fluency and thus possible frontal lobe functioning impairment.
Objective:
Verbal fluency (VF) tasks are widely used to investigate children's lexical knowledge and executive functions skills. Consistency of measurement of the strategic retrieval components is still an issue and performance of Brazilian-Portuguese speaking children are currently not available. A cross-sectional study investigated the effects of age, school type (public × private) and the influence of language, memory and inhibitory control on VF.
Method:
We assessed 414 Brazilian children, aged 6-12, in the number of words produced and both clustering and switching components, with two measures of VF: letter (LVF) and semantic (SVF).
Results:
Analysis of the number of words produced showed a significant increase between 6-8-year-olds, 9-10-year-olds and 11-12-year-olds in SVF, while in LVF, the differences were significant only in the later age group. In SVF, the numbers of clusters and switches increased with age, whereas in LVF, the number of switches increased in all age groups, but clusters increased only in the older group. Structural equation model analyses showed that oral and written language, verbal memory and inhibitory control are associated with VF performance and IQ, while age mediated VF performance.
Conclusions:
The results indicate a different development pattern between LVF and SVF in the number of words produced and in clustering and switching, with the latter predicting VF performance in words produced. VF development is shown to depend on language, memory and inhibitory control. Our results have important implications to clinical neuropsychology.
Objective:
To describe the methodology utilized to calculate reliability and the generation of norms for 10 neuropsychological tests for children in Spanish-speaking countries.
Method:
The study sample consisted of over 4,373 healthy children from nine countries in Latin America (Chile, Cuba, Ecuador, Guatemala, Honduras, Mexico, Paraguay, Peru, and Puerto Rico) and Spain. Inclusion criteria for all countries were to have between 6 to 17 years of age, an Intelligence Quotient of≥80 on the Test of Non-Verbal Intelligence (TONI-2), and score of <19 on the Children's Depression Inventory. Participants completed 10 neuropsychological tests. Reliability and norms were calculated for all tests.
Results:
Test-re-test analysis showed excellent or good- reliability on all tests (r's>0.55; p's<0.001) except M-WCST perseverative errors whose coefficient magnitude was fair. All scores were normed using multiple linear regressions and standard deviations of residual values. Age, age2, sex, and mean level of parental education (MLPE) were included as predictors in the models by country. The non-significant variables (p > 0.05) were removed and the analysis were run again.
Conclusions:
This is the largest Spanish speaking children and adolescents normative study in the world. For the generation of normative data, the method based on linear regression models and the standard deviation of residual values was used. This method allows determination of the specific variables that predict test scores, helps identify and control for collinearity of predictive variables, and generates continuous and more reliable norms than those of traditional methods.
Objective:
To conduct a literature review of the administration and scoring criteria used in normative studies of verbal fluency tests (VFT), and to propose a new model for the administration and scoring of phonological, semantic, and action VFT for use in Spanish-speakers.
Methods:
A literature search was performed using four databases Dialnet, ProQuest (PsycINFO, PsycArticles), Science Direct (Elsevier), and PubMed and 47 articles met the following criteria: 1) articles which contained normative data of phonological, semantic, or action VFT, 2) published between 2000 and 2015, 3) published in English or Spanish, 4) used healthy population.
Results:
Of 2087 citations retrieved, 47 eligible studies were reviewed. The majority of the studies have been conducted in the USA, and with English and Spanish speakers. Only 12 studies provided the instruction, and 23 clearly describe the scoring guidelines. Moreover, among the studies that provided these information important discrepancies were found. Therefore, a new administration and scoring guidelines are presented, which may resolve this problem and be utilized in Spanish speaking countries.
Conclusions:
This review showed that still there is no consensus regarding the administration and scoring of VFT. A new method of administration and scoring is presented that can be use with Spanish-speakers.
Purpose:
Verbal fluency tests are often used as part of an assessment battery to investigate children's lexical knowledge as well as executive function skills. To date, however, issues surrounding consistency of measurement cloud comparisons across studies, with the developmental performance of Australian-English speaking children also currently lacking. This study tracked verbal fluency development as measured by two semantic fluency tasks that included coding of fluency, clustering and switching type responses.
Method:
Participants included 355 typically developing Australian-English speaking children (4-10 years) and 46 young adults. Total fluency was determined by the number of words produced for each category (Animals or Food), minus repetitions and rule violations. Semantic clusters (words generated within a subcategory) were coded while switches between single words or subcategories were differentiated and coded as either hard or cluster switches.
Result:
Fluency showed consistent improvement over age. Cluster Switches and Hard Switches showed some evidence of a plateau in performance relative to fluency, but in opposite direction. Other measures showed no strong trends over age. Results were similar for both semantic categories.
Conclusion:
Our results highlight the rich information available within a semantic fluency task and the importance of differentiating hard and cluster switches in paediatric samples.
Objective:
Intraclass correlation coefficient (ICC) is a widely used reliability index in test-retest, intrarater, and interrater reliability analyses. This article introduces the basic concept of ICC in the content of reliability analysis.
Discussion for researchers:
There are 10 forms of ICCs. Because each form involves distinct assumptions in their calculation and will lead to different interpretations, researchers should explicitly specify the ICC form they used in their calculation. A thorough review of the research design is needed in selecting the appropriate form of ICC to evaluate reliability. The best practice of reporting ICC should include software information, "model," "type," and "definition" selections.
Discussion for readers:
When coming across an article that includes ICC, readers should first check whether information about the ICC form has been reported and if an appropriate ICC form was used. Based on the 95% confident interval of the ICC estimate, values less than 0.5, between 0.5 and 0.75, between 0.75 and 0.9, and greater than 0.90 are indicative of poor, moderate, good, and excellent reliability, respectively.
Conclusion:
This article provides a practical guideline for clinical researchers to choose the correct form of ICC and suggests the best practice of reporting ICC parameters in scientific publications. This article also gives readers an appreciation for what to look for when coming across ICC while reading an article.
Verbal fluency tasks are simple behavioral measures useful in assessing word retrieval abilities. Among the verbal fluency tasks, the utility of the Phonemic Fluency Task in children has received less attention. As the task is dependent on phonemic characteristics of each language, there is a great need for understanding its developmental trend. The present study, therefore, aims to delineate the performance on phonemic fluency in typically developing Malayalam-speaking children. Verbal fluency performance on 2 tasks of phonemic fluency was tested using a cross-sectional study design among 1,015 school-going Malayalam-speaking typically developing children aged 5 to 15 years old. Performance with respect to word productivity and clustering-switching measures was analyzed. The effect of age, gender, and tasks on the outcome measures were investigated in the present study. Study findings revealed a positive influence of age with no statistically significant gender effects. Children employed both task-discrepant and task-consistent organizational strategies during tasks of phonemic fluency, dependent purely on the Malayalam language. Future research focusing on developmental trends across different languages is vital for enhancing the task's clinical sensitivity and specificity among childhood disorders.
El objetivo principal de este estudio consistió en la baremación y el análisis del desarrollo evolutivo, en una amplia muestra de población infantil de habla española, de dos pruebas destinada a la evaluación de la fluidez verbal (semántica y fonológica). Analizamos el desarrollo de ambas tareas dentro de un contexto de diseño transversal. Se seleccionó una muestra de 1.032 sujetos con edades comprendidas entre los 6 años y 3 meses y los 12 años y cuatro meses que cursaban entre primero y sexto de educación primaria. La fluidez verbal semántica se evaluó con la tarea de evocación ‘de animales en un minuto’ y la fluidez verbal fonológica se evaluó con las consignas ‘F, A, M’. Los resultados muestran una mejora progresiva en el rendimiento en función de la edad en ambas pruebas. Se presentan tablas de medias, desviación estándar y percentiles para los distintos grupos de edad.
The verbal fluency task is a widely used neuropsychological test of word retrieval efficiency. Both category fluency (e.g., list animals) and letter fluency (e.g., list words that begin with F) place demands on semantic memory and executive control functions. However letter fluency places greater demands on executive control than category fluency, making this task well-suited to investigating potential bilingual advantages in word retrieval. Here we report analyses on category and letter fluency for bilinguals and monolinguals at four ages, namely, 7-year-olds, 10-year-olds, young adults, and older adults. Three main findings emerged: 1) verbal fluency performance improved from childhood to young adulthood and remained relatively stable in late adulthood; 2) beginning at 10-years-old, the executive control requirements for letter fluency were less effortful for bilinguals than monolinguals, with a robust bilingual advantage on this task emerging in adulthood; 3) an interaction among factors showed that category fluency performance was influenced by both age and vocabulary knowledge but letter fluency performance was influenced by bilingual status.
To investigate developmental changes that take place in verbal fluency (VF) performance during early childhood, a VF task was administered to 225 healthy, Dutch-speaking children aged between 4.14 and 6.89 years. Three categories of VF outcome measures were included: i.e., word productivity, mean cluster size, and number of switches. Age influenced performance on all VF outcome measures linearly; i.e., older children produced more words, made longer clusters, and switched more. Higher levels of intelligence were associated with increased VF word productivity, but not with measures of switching and clustering. When leaving intelligence out of these analyses, we additionally found an interaction between level of parental education (LPE) and sex on total word productivity, i.e., girls with parents who had lower LPE produced fewer words than the other children. Furthermore, a similar interaction of LPE and sex was found for the number of switches: i.e., girls who had parents with lower LPE made fewer switches than the other children. Findings suggest that even in 4 to 6-year-old children important changes take place over time in VF and in processes underlying successful performance. Attention should be paid to age-extrinsic factors, such as LPE and sex, since these have been found to influence VF performance in young children.
This study highlights differences in cognitive strategies in children and adolescents with and without autism spectrum disorders (n = 52) on a verbal fluency task (naming as many words as possible (e.g. animals) within 60 s). The ability to form clusters of words (e.g. farm animals like "cow-horse-goat") or to switch between unrelated words (e.g. "snake" and "cat") was analyzed using a coding method that more stringently differentiates between these strategies. Results indicated that children and adolescents with autism spectrum disorders switched less frequently, but produced slightly larger clusters than the comparison group, resulting in equal numbers of total words produced. The currently used measures of cognitive flexibility suggest atypical, but possibly equally efficient, fluency styles used by individuals with autism spectrum disorders.
Verbal fluency tasks are commonly used in cognitive and developmental neuropsychology in assessing executive functions, language skills as well as divergent thinking. Twenty-two typically developing children and 22 children with ADHD between the ages of 8 and12 years were examined using verbal fluency tasks, prepotent response inhibition, and working memory tests. The clinical group showed impaired inhibitory and spatial working memory processes. We used different qualitative analyses of verbal fluency tasks to explore the lexical and executive strategies (word clustering and switching), and the temporal properties of the responses. Children with ADHD had a leeway in applying relevant lexical or executive strategies related to difficulties in strategy using. The reduced efficiency of children with ADHD in semantic fluency task is based on suboptimal shifting between word clusters and is related to the lack of ability of producing new clusters of items. The group difference appeared at the level of accessing and/or activating common words; however, the executive process of searching the lexicon extensively is intact.
Word-retrieval abilities in children can be assessed using word generation or verbal fluency task. The ability to retrieve is related to the individual's ability to retrieve associated words from the mental lexicon in an organized manner. The present study focuses on the developmental aspects of semantic fluency in 1,015 Malayalam-speaking children in the age range of 5 years to 15 years across both genders. The study revealed a developmental trend in the mean total number of correct word scores, number of clusters generated, and switching scores; however, mean cluster size did not show any statistically significant variation. Further, the scores did not vary across genders. Overall, the study indicated a linear developmental trend during verbal fluency with the increase in complexity of strategy use.
Verbal fluency (VF) tasks are extensively used to measure strategic retrieval and executive functioning. Results for total production of words, clustering and switching strategies, and performance over time for Spanish-speaking children are provided. A total of 120 children, ranging in age from 8 to 11, were divided by age into two groups and evaluated. A higher total score for words produced in the semantic compared with the phonological task, a correlation between clustering and switching strategies and total score, and decreased task performance over time were evidenced. These scores were higher in the older group. Moreover, an association was found between verbal fluency tasks, strategies employed, and cognitive executive functions. This indicates that clustering and switching strategies provide indicators of strategic retrieval and executive processes. Together the results suggest that these fluency scores are valuable to measure underlying cognitive processes and retrieval strategies and therefore could be useful to assess executive function deficits in children.
Rhyming words, as in songs or poems, is a universal feature of human language across all ages. In the present fMRI study a novel overt rhyming task was applied to determine the neural correlates of rhyme production. Fifteen right-handed healthy male volunteers participated in this verbal fluency study. Participants were instructed to overtly articulate as many words as possible either to a given initial letter (LVF) or to a semantic category (SVF). During the rhyming verbal fluency task (RVF), participants had to generate words that rhymed with pseudoword stimuli. On-line overt verbal responses were audiotaped in order to correct the imaging results for the number of generated words. Fewer words were generated in the rhyming compared to both the lexical and the semantic condition. On a neural level, all language tasks activated a language network encompassing the left inferior frontal gyrus, the middle and superior temporal gyri as well as the contralateral right cerebellum. Rhyming verbal fluency compared to both lexical and semantic verbal fluency demonstrated significantly stronger activation of left inferior parietal region. Generating novel rhyme words seems to be mainly mediated by the left inferior parietal lobe, a region previously found to be associated with meta-phonological as well as sub-lexical linguistic processes.
Tallberg, I.M., Carlsson, S. & Lieberman, M. (2011). Children’s word fluency strategies. Scandinavian Journal of Psychology 52, 35–42.
Two word fluency tasks, the FAS letter fluency task and the “animal” semantic fluency task, were administered to 130 healthy Swedish-speaking children between 6 and 15 years of age. The main aim was to gather normative data on these word fluency tasks for Swedish-speaking children. Another purpose was to examine the switching and clustering strategies used, along with the occurrence of erroneous responses, in relation to demographic data and number of words retrieved. Both phonological and semantic analyses of switching and clustering were conducted. Higher age was found to be related to a more effective use of phonological and semantic switching and clustering strategies. The reference data resulting from this study may be of clinical value in examinations of children with various diagnoses, including language impairment.
We investigated age-related improvement in semantic category verbal fluency (VF) in 309 Dutch schoolchildren attending first to ninth grade. Quantitative analyses of number of correct responses as a function of time as well as qualitative analyses of clustering and switching were conducted. Overall, Dutch VF task performance, i.e., number of correct responses over 60 seconds, was not established before mid-adolescence. This is in line with previously published studies, using VF number of correct responses over 60 seconds as the main outcome measure and examining VF task performance across other cultures and languages (e.g., Italian, French, Hebrew). Next, mean cluster size, a measure of lexico-semantic knowledge, was not established until at least grade 3. In contrast, performance on the VF outcome measures "number of switches/clusters" was established at least 4 years later. Qualitative and quantitative Design Fluency (DF) outcome measures support the notion that the numbers of switches/clusters are valid measures of higher order cognitive functions, such as strategy use and cognitive flexibility. In line of this, VF number of correct responses during 16-60 seconds, a measure of controlled information processing, is established at least 2 years later (i.e., grades 7-8) than number of correct responses during the first 15 seconds time slide, a measure of automatic processing. Finally, environment, i.e., the level of parental education, primarily affected automatic and lexico-semantic knowledge. No effects of sex on VF performance were found. These data suggest that the alternative scoring methods of VF tasks can be used to acquire knowledge on development of lower and higher order cognitive functions in healthy children and the influence of the environment on it.
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.
The present study used a behavioral version of an anti-saccade task, called the 'faces task', developed by [Bialystok, E., Craik, F. I. M., & Ryan, J. (2006). Executive control in a modified anti-saccade task: Effects of aging and bilingualism. Journal of Experimental Psychology: Learning, Memory, and Cognition, 32, 1341-1354] to isolate the components of executive functioning responsible for previously reported differences between monolingual and bilingual children and to determine the generality of these differences by comparing bilinguals in two cultures. Three components of executive control were investigated: response suppression, inhibitory control, and cognitive flexibility. Ninety children, 8-years old, belonged to one of three groups: monolinguals in Canada, bilinguals in Canada, and bilinguals in India. The bilingual children in both settings were faster than monolinguals in conditions based on inhibitory control and cognitive flexibility but there was no significant difference between groups in response suppression or on a control condition that did not involve executive control. The children in the two bilingual groups performed equivalently to each other and differently from the monolinguals on all measures in which there were group differences, consistent with the interpretation that bilingualism is responsible for the enhanced executive control. These results contribute to understanding the mechanism responsible for the reported bilingual advantages by identifying the processes that are modified by bilingualism and establishing the generality of these findings across bilingual experiences. They also contribute to theoretical conceptions of the components of executive control and their development.
Developmental changes in children's verbal fluency and confrontation naming were explored in this study. One hundred and sixty children (ages 5 years and 11 months to 11 years and 4 months) completed two verbal fluency tasks (phonemic and semantic) and the Boston Naming Test (BNT). Normative data were compiled for the BNT and the phonemic and semantic fluency tasks. With the exception of the phonemic fluency task, all tests showed a linear increase from year-groups I to V, with a significant increase between year-groups I and II. Principal Component Factor Analysis was conducted to determine whether the tests evaluated similar or different functions. Two factors emerged: the first involving all of the measurements and the second explaining exclusively the phonemic fluency. These results make it possible to conclude that children also seem to have different subsystems responsible for the analysis and processing of different aspects of language.
Normative data for clustering and switching on verbal fluency tasks are provided. Four hundred and eleven healthy adults between the ages of 18 and 91 were given tests of phonemic fluency (FAS or CFL) and semantic fluency (Animals and Supermarket). Raw scores were corrected for demographic (i.e., age, education, and sex) and test (i.e., fluency form) variables that were determined to make sizable contributions to fluency performance. These normative data should be useful for clinicians and researchers in determining the nature of the fluency impairment in any given individual.
We compared three approaches to scoring qualitative aspects of verbal fluency performance in 88 healthy young adults. Phonemic and semantic fluency output was scored for word clustering and switching between clusters. Convergent validity analyses using other tests presumed to tap into strategy use (California Verbal Learning Test, Ruff Figural Fluency Test) support scoring of phonemic and semantic clusters on both fluency tasks. Task-discrepant clustering (e.g., semantic clustering on phonemic fluency) may index intentional strategy use on both fluency tasks, whereas task consistent clustering (e.g., phonemic clustering on phonemic fluency) appears strategic only on semantic fluency. Switching can be decomposed into subtypes that appear to reflect different cognitive processes on phonemic versus semantic fluency. Principal components analyses suggest that earlier scoring methods do not fully capture the "process" aspects of verbal fluency performance.
Although there have been significant theoretical advances in the field of child neuropsychology, developmental features of adolescence have received less attention. Progress in clinical practice is restricted due to a lack of well-standardized, developmentally appropriate assessment techniques. This article addresses these issues in relation to executive skills. These abilities are targeted for 2 reasons: first, because they are often considered to be mature during late childhood and adolescence, despite limited investigation in this age range; and second, because of their central importance to efficient day-to-day functioning. Using a normative sample of 138 children, aged 11.0 to 17.11 years, this article plots the development of executive skills through late childhood and early adolescence and interprets progress in these skills with reference to current neurological and cognitive theory.
This study examined aspects of verbal fluency performance of children with Specific Language Impairment (SLI) and typically developing children matched on age and Block Design scores. While children with SLI showed deficits in verbal fluency compared to their peers, they showed the same pattern of performance on phonemic compared to semantic fluency trials. Children with SLI and normally developing children also demonstrated equivalent rates of clustering and switching, measures hypothesized to reflect aspects of frontal lobe functioning, when the overall number of exemplars was taken into account. The absence of a condition by group effect supports general processing limitation accounts of SLI, while the absence of group differences on cluster size and switches supports language-based processing accounts of SLI.
This review paper outlines the issues associated with the assessment of executive function (EF) in children and adolescents, and describes the developmental profile of executive processes across childhood. At the outset, EF is defined, and cognitive and behavioral impairments associated with executive dysfunction (EDF) are described. A developmental model of EF is proposed incorporating four discrete but inter-related executive domains (attentional control, cognitive flexibility, goal setting, and information processing) which operate in an integrative manner to enable "executive control". Characteristics that constitute traditional EF measures are discussed, as are the problems associated with test interpretation. The ecological validity of EF tests and neuropsychological assessment procedures are examined, and adjunct methods of measurement are presented to enable a more comprehensive and valid assessment of EF. Based on developmental and normative studies, the maturation of executive domains is mapped. Attentional control appears to emerge in infancy and develop rapidly in early childhood. In contrast, cognitive flexibility, goal setting, and information processing experience a critical period of development between 7 and 9 years of age, and are relatively mature by 12 years of age. A transitional period is thought to occur at the beginning of adolescence, and shortly after "executive control" is likely to emerge. In order to confirm our current understanding of EF development and further enhance our understanding of brain-behavior relationships, longitudinal studies incorporating structural and functional neuroimaging are required.