Enhancement of phonemic verbal fluency in multilingual young adults by transcranial random noise stimulation

Several studies have analyzed the effects of transcranial direct current stimulation on verbal fluency tasks in non-clinical populations. Nevertheless, the reported effects on verbal fluency are inconsistent. In addition, the effect of other techniques such as transcranial random noise stimulation (tRNS) on verbal fluency enhancement has yet to be studied in healthy multilingual populations. This study aims to explore the effects of tRNS on verbal fluency in healthy multilingual individuals. Fifty healthy multilingual (Spanish, English and Basque) adults were randomly assigned to a tRNS or sham group. Electrodes were placed on the left dorsolateral prefrontal cortex and left inferior frontal gyrus. All participants performed phonemic and semantic verbal fluency tasks before, during (online assessment) and immediately after (offline assessment) stimulation in three different languages. The results showed significantly better performance by participants who received tRNS in the phonemic verbal fluency tasks in Spanish (in the online and offline assessment) and English (in the offline assessment). No differences between conditions were found in Basque nor semantic verbal fluency. These findings suggests that tRNS on the left prefrontal cortex could help improve phonemic, yet not semantic, fluency in healthy multilingual adults.

The Effect of Language Dominance on Classic Semantic, Action, Emotional, and Phonemic Fluency in Unbalanced Bilinguals

OBJECTIVE

Verbal fluency evaluation in bilingual speakers should include dual-language assessment to obtain a comprehensive profile of word retrieval abilities. This study is the first to compare classic semantic, action, emotional, and phonemic fluency in terms of the magnitude of their performance gaps between the dominant and nondominant language in unbalanced bilingual speakers. We also examined the quantitative relationship between language dominance and verbal fluency performance.

METHOD

Twenty-six bilingual adults completed a comprehensive set of classic semantic ("animals," "vegetables"), action ("do"), emotional ("happy," "sad," "afraid"), and phonemic ("F," "A," "S") fluency tasks in their dominant language (English) and nondominant language (Spanish) in two sessions on separate days. Participants also completed subjective and objective measures of language proficiency.

RESULTS

All tasks yielded fewer correct responses in the nondominant language. The between-languages performance gap was the largest for "animals" and the smallest for emotional fluency. "Happy" yielded the most balanced performance among all semantic tasks and a positivity bias that was unaffected by language dominance. Finally, language dominance scores computed by a newly developed formula indicated relationships between self-rated proficiency and fluency performance.

CONCLUSIONS

This study provides preliminary, normative data of classic semantic, action, emotional, and phonemic fluency that could be used to gauge unbalanced bilingual speakers' performance. Significant impacts of language dominance on "animals" demand caution in using this widely used classic semantic category in evaluating bilingual speakers' performance. The data also underscore the robustness of positivity biases in emotional fluency and the validity of using subjective measures to supplement neuropsychological assessment of fluency performance.

Geographic variability in limited English proficiency: A cross-cultural study of cognitive profiles

OBJECTIVE

This study was designed to evaluate the effect of limited English proficiency (LEP) on neurocognitive profiles.

METHOD

Romanian (LEP-RO; n = 59) and Arabic (LEP-AR; n = 30) native speakers were compared to Canadian native speakers of English (NSE; n = 24) on a strategically selected battery of neuropsychological tests.

RESULTS

As predicted, participants with LEP demonstrated significantly lower performance on tests with high verbal mediation relative to US norms and the NSE sample (large effects). In contrast, several tests with low verbal mediation were robust to LEP. However, clinically relevant deviations from this general pattern were observed. The level of English proficiency varied significantly within the LEP-RO and was associated with a predictable performance pattern on tests with high verbal mediation.

CONCLUSIONS

The heterogeneity in cognitive profiles among individuals with LEP challenges the notion that LEP status is a unitary construct. The level of verbal mediation is an imperfect predictor of the performance of LEP examinees during neuropsychological testing. Several commonly used measures were identified that are robust to the deleterious effects of LEP. Administering tests in the examinee's native language may not be the optimal solution to contain the confounding effect of LEP in cognitive evaluations.

Speech disfluencies in bilingual Greek-English young adults

PURPOSE

The purpose of this study was to investigate the frequency and types of disfluencies in Greek-English bilingual adults across naturalistic speech samples and compare frequency and types of disfluencies between the participants' L1 and L2.

METHODS

Participants in the study included 26 Greek-English bilingual young adults. All participants were sequential bilinguals, whose first language was Greek and second language was English. Two speech samples were collected in each language, a conversational and a narrative sample, which were subsequently analyzed for the frequency and types of disfluencies.

RESULTS

Results indicated that participants produced more typical disfluencies in English compared to Greek across speaking samples. The most frequent types of disfluencies were filled pauses and vowel prolongations (without tension or struggle) across speaking samples and languages.

CONCLUSION

Our results revealed differences in the types and frequencies of disfluencies produced in participants' native compared to their second language. Results add to the growing body of literature addressing the manifestation of speech disfluencies in bilingual speakers.

Effects of age, gender, and education on task performance and prefrontal cortex processing during emotional and non-emotional verbal fluency tests

The emotional semantic fluency test (SFT) is an emerging verbal fluency test that requires controlled access to emotional lexical information. Currently, how demographic variables influence neurocognitive processing during this test remains elusive. The present study compared the effects of age, gender, and education on task performance and prefrontal cortex (PFC) processing during the non-emotional and emotional SFTs. One-hundred and thirty-three Cantonese-speaking adults aged 18-79 performed the non-emotional and emotional SFTs while their PFC activation was measured using functional near-infrared spectroscopy. Results showed that more education predicted better non-emotional SFT performance, whereas younger age, being female, and more education predicted better emotional SFT performance. Only age significantly affected PFC activation during the SFTs, and the effect was comparable between the two SFTs. Thus, compared with its non-emotional analog, the emotional SFT is influenced by overlapping yet distinct demographic variables. There is a similar age-related reorganization of PFC function across SFT performances.

Dual-Language Testing of Emotional Verbal Fluency: A Closer Look at "Joy," "Sadness," "Fear," "Anger," and "Disgust"

OBJECTIVE

Assessing neuropsychological functions of dual-language speakers with semantic verbal fluency should consider the impact of language proficiency. Much evidence for the proficiency effect is found in tasks targeting neutral words. The proficiency effect on emotional verbal fluency (Emo-VF) that targets emotional word retrieval, however, is far from conclusive. This study aimed to clarify the proficiency effect on Emo-VF, specifically the extent to which language proficiency impacted positive and negative word retrieval comparably. In addition, the study examined the extent to which dual-languages speakers produced duplicated items and unique, non-duplicated items in each of two languages tested.

METHOD

Thirty-two adult participants completed Emo-VF tasks that targeted a comprehensive set of basic emotions ("joy," "sadness," "fear," "anger," "disgust") in English and Spanish in two sessions separated by at least 72 h. All participants exhibited greater proficiency in English than in Spanish according to subjective and objective measures of language proficiency.

RESULTS

Verbal productivity was comparably lowered for all emotions in the less proficient language. Differences among categories were consistent between languages, with "joy" eliciting more words than other emotions, and "fear" yielding the highest productivity among negative emotions. Finally, dual-language speakers produced a significant number of unique items in different languages, especially for "fear."

CONCLUSION

Language proficiency exerts a general effect on positive and negative word retrieval. The study extends previous work by revealing differences between "fear" and other negative categories in addition to replicating positivity biases in unbalanced dual-language speakers. Dual-language testing is valuable in capturing the richness of emotional word repertoire associated with different languages.

Cross-Cultural Performance Validity Testing: Managing False Positives in Examinees with Limited English Proficiency

Base rates of failure (BR_Fail) on performance validity tests (PVTs) were examined in university students with limited English proficiency (LEP). BR_Fail was calculated for several free-standing and embedded PVTs. All free-standing PVTs and certain embedded indicators were robust to LEP. However, LEP was associated with unacceptably high BR_Fail (20-50%) on several embedded PVTs with high levels of verbal mediation (even multivariate models of PVT could not contain BR_Fail). In conclusion, failing free-standing/dedicated PVTs cannot be attributed to LEP. However, the elevated BR_Fail on several embedded PVTs in university students suggest an unacceptably high overall risk of false positives associated with LEP.

Frontal cortical activation during emotional and non-emotional verbal fluency tests

There has been growing recognition of the utility of combining the verbal fluency test and functional near-infrared spectroscopy (fNIRS) to assess brain functioning and to screen for psychiatric disorders. Recently, an emotional analogue of the semantic fluency test (SFT) has been developed that taps partly different processes from conventional verbal fluency tests. Nevertheless, neural processing during the emotional SFT remains elusive. Here, fNIRS was used to compare frontal cortical activation during emotional and non-emotional SFTs. The goal was to determine whether the emotional SFT activated overlapping yet distinct frontal cortical regions compared with the conventional, non-emotional SFT. Forty-three healthy young adults performed the emotional and non-emotional SFTs while hemodynamic changes in the bilateral frontopolar, dorsomedial, dorsolateral, ventrolateral, and posterolateral frontal cortices were measured by fNIRS. There were significant increases in oxyhemoglobin concentration and significant decreases in deoxyhemoglobin concentration (i.e., activation) in frontopolar, dorsolateral, and ventrolateral frontal regions during both the non-emotional and emotional SFTs. Also, complementary analyses conducted on changes in the two chromophores using classical and Bayesian hypothesis testing suggested that comparable frontal cortical regions were activated while performing the two tests. This similarity in activation occurred in a context where non-emotional and emotional SFT performances exhibited differential relationships with the overall level of negative mood symptoms. In conclusion, frontal cortical activation during the emotional SFT is similar to that during the conventional, non-emotional SFT. Given that there is evidence for discriminant validity for the emotional SFT, the neural mechanisms underlying the uniqueness of this test warrant further investigation.

The structure of lay-concepts within the fear spectrum revealed using emotional verbal fluency

Given the fact that natural language analysis can distinguish constituents of mental constructs, the present research was designed to investigate the structure of concepts related to the broad spectrum of emotions comprising worry, fear, anxiety, and panic, which in this article is referred to as the ‘fear spectrum’. A new technique presented here is based on a word association task and enables a description of the structure of emotion concepts. The technique is a variant of a verbal fluency task, i.e. emotional verbal fluency technique. Two studies have been conducted: the first to examine the cognitive structure of concepts within the fear spectrum (n = 280, 150 women, 130 men) and the second to confirm the stability of word association in the fear tasks and differentiation of the fear concepts in relation to trait anxiety and dogmatism (n = 190, 100 women, 90 men). A hierarchical clustering analysis, based on the linguistic material, i.e. words produced by the participants for the task of anxiety, was performed to present in what way the emotional verbal fluency technique can be applied to explore the structure of emotional concepts. According to our results, there is a relatively constant tendency in producing semantic clusters (emotional word association) among lay people. Moreover, produced clusters allow to describe the structure and to differentiate lay-concepts within the fear spectrum, such as worry, fear, anxiety, panic [respectively in Polish: obawa, lęk, strach, panika].

The emotion word fluency test as an embedded performance validity indicator - Alone and in a multivariate validity composite

OBJECTIVE

This project was designed to cross-validate existing performance validity cutoffs embedded within measures of verbal fluency (FAS and animals) and develop new ones for the Emotion Word Fluency Test (EWFT), a novel measure of category fluency.

METHOD

The classification accuracy of the verbal fluency tests was examined in two samples (70 cognitively healthy university students and 52 clinical patients) against psychometrically defined criterion measures.

RESULTS

A demographically adjusted T-score of ≤31 on the FAS was specific (.88-.97) to noncredible responding in both samples. Animals T ≤ 29 achieved high specificity (.90-.93) among students at .27-.38 sensitivity. A more conservative cutoff (T ≤ 27) was needed in the patient sample for a similar combination of sensitivity (.24-.45) and specificity (.87-.93). An EWFT raw score ≤5 was highly specific (.94-.97) but insensitive (.10-.18) to invalid performance. Failing multiple cutoffs improved specificity (.90-1.00) at variable sensitivity (.19-.45).

CONCLUSIONS

Results help resolve the inconsistency in previous reports, and confirm the overall utility of existing verbal fluency tests as embedded validity indicators. Multivariate models of performance validity assessment are superior to single indicators. The clinical utility and limitations of the EWFT as a novel measure are discussed.

Emotional and Non-Emotional Verbal Fluency in Native and Non-Native Speakers

OBJECTIVE

Native speakers frequently outperform non-native speakers on classic semantic verbal fluency tasks that target concrete non-emotional word retrieval. Much less is known about performance differences in retrieval of emotional words, which are abstract and crucial to social-emotional competence. This study compared native and non-native speakers' verbal productivity on emotional and non-emotional verbal fluency tasks.

METHOD

Forty-seven native and 37 non-native speakers of English participated in the study. Participants completed seven semantic verbal fluency tasks in English including classic semantic (e.g., "animals"), action (e.g., "things people do"), and emotional variants (e.g., "things that make people happy"). Subjective and objective measures of English proficiency, information about language usage, and cognitive measures (working memory) were obtained for each participant.

RESULTS

Verbal productivity for classic semantic, action, and emotional verbal fluency was lower for non-native speakers. Smaller language-specific vocabulary in non-native speakers did not moderate positivity biases in emotional verbal fluency. Subjective and objective language proficiency measures were less predictive of performance on the emotional than the non-emotional verbal fluency tasks.

CONCLUSION

Non-native speakers perform more poorly than native speakers on semantic verbal fluency in English for both emotional and non-emotional variants. Positivity biases are not moderated by language proficiency and are reliable features of emotional verbal fluency. Proficiency measures may be less effective in predicting generation of emotional than neutral words.

The Emotional Verbal Fluency Task: A Close Examination of Verbal Productivity and Lexical-Semantic Properties

Purpose Emotional verbal fluency (Emo-VF) has the potential to expand neuropsychological assessment by providing information about affective memory retrieval. The usability of Emo-VF is limited, however, by significant variations in task administration and the lack of information about Emo-VF responses. This study investigated verbal productivity and the lexical-semantic properties of responses on positive and negative Emo-VF tasks. Comparing Emo-VF to non-Emo-VF tasks used regularly in neuropsychological assessment provided additional information about the basic characteristics of Emo-VF tasks. Method Twenty-five adult native speakers provided verbal responses to three Emo-VF ("happy," "sad," "negative emotions") and two non-Emo-VF categories ("animals," "things people do"). Verbal productivity was measured at the word and syllable levels. Multiple large-scale data corpora were used to estimate the lexical-semantic properties of the verbal responses. Results There was a robust positivity bias in verbal productivity within Emo-VF tasks. Emo-VF tasks tended to elicit longer words than "animals" and "things people do," which might impact the results of verbal productivity analyses, especially in comparisons with "things people do." Within Emo-VF tasks, negative Emo-VF elicited words from a wider range of valence than positive Emo-VF tasks. Similarities (e.g., word length and complexity) and differences (e.g., concreteness, age of acquisition) were found between positive and negative Emo-VF tasks. Conclusions The study provided information about the basic characteristics of Emo-VF tasks, which included evidence for a robust positivity bias, suggestions for analyses of verbal productivity (e.g., consideration of word length), and lexical-semantic properties associated with positive and negative Emo-VF tasks using corpora data.

Verbal fluency in three Spanish-English bilingual speakers with TBI

This study investigated differences between healthy bilingual participants and bilingual participants with traumatic brain injury (TBI) on verbal fluency tasks. The performance of three Spanish-English bilingual speakers with traumatic brain injury was compared to the performance of 30 neurotypical bilingual speakers on tasks of category and letter verbal fluency in English and Spanish. Responses were analyzed for total number of correct productions, differences in correct productions between languages, average cluster size, total number of switches, and rates of language choice errors. The data were analyzed using predicted scores from regression equations based on neurotypical data and modified t-tests. Analyses revealed significantly lower total output than predicted by the regression equations for both task types and in both languages for one TBI participant. The same participant demonstrated significantly lower total number of switches than the neurotypical group. Two participants demonstrated higher rates of language choice errors than the neurotypical group. There were no significant differences between TBI participants and the neurotypical group for average cluster size. There were no significant differences between predicted and obtained values for differences between English and Spanish total number correct in each task type. Results are discussed in the context of individual cognitive and linguistic profiles of the TBI participants.

Schizotypal personality and semantic functioning: Revisiting category fluency effects in a subclinical sample

Semantic disturbances have been proposed as a possible cause of formal thought disorder in schizophrenia. Fluency tasks, in which volunteers are asked to produce as many exemplars as they can for a given category during one minute, are usually applied to the assessment of semantic processing. However, studies associating fluency and proneness to psychosis have provided conflicting results so it is not clear whether these disturbances can be identified at subclinical stages. We conducted two experiments. In the first one, 71 volunteers completed written category fluency tasks with four semantic categories (animals, fruits, clothing and vehicles). In the second experiment, 77 new participants completed oral category and phonological fluency tasks (words starting with f, t, p and c). In both experiments, we assessed schizotypal personality and vocabulary size. Schizotypal traits were not reliably associated with either productivity or originality of the responses in any experiment. In contrast, vocabulary size significantly predicted the participants' scores in all the tasks. Along with results of other recent studies, our data cast doubt on the reliability of previous observations pointing out an association between schizotypy and lexical-semantic disturbances, at least in relation to productivity and originality in fluency tests.