Language proficiency and executive control in proactive interference: evidence from monolingual and bilingual children and adults

Two studies are reported in which monolingual and bilingual children (Study 1) and adults (Study 2) completed a memory task involving proactive interference. In both cases, the bilinguals attained lower scores on a vocabulary test than monolinguals but performed the same on the proactive interference task. For the children, bilinguals made fewer intrusions from previous lists even though they recalled the same number of words. For the adults, bilinguals recalled more words than monolinguals when the scores were corrected for differences in vocabulary. In addition, there was a strong effect of vocabulary in which higher vocabulary participants recalled more words irrespective of language group. These results point to the important role of vocabulary in verbal performance and memory. They also suggest that bilinguals may compensate for weaker language proficiency with their greater executive control to achieve the same or better levels of performance as monolinguals.     

Perspective-taking ability in bilingual children: Extending advantages in executive control to spatial reasoning

Monolingual and bilingual 8-year-olds performed a computerized spatial perspective-taking task. Children were asked to decide how an observer saw a four-block array from one of three different positions (90°, 180°, and 270° counter-clockwise from the child's position) by selecting one of four responses – the correct response, the egocentric error, an incorrect choice in which the array was correct but in the wrong orientation for the viewer, and an incorrect choice in which the array included an internal spatial error. All children performed similarly on background measures, including fluid intelligence, but bilingual children were more accurate than monolingual children in calculating the observer's view across all three positions, with no differences in the pattern of errors committed by the two language groups. The results are discussed in terms of the effect of bilingualism on modifying performance in a complex spatial task that has implications for academic achievement.     

Components of executive control with advantages for bilingual children in two cultures

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.     

Episodic and semantic memory in bilingual and monolingual children

Although bilinguality has been reported to confer advantages upon children with respect to various cognitive abilities, much less is known about the relation between memory and bilinguality. In this study, 60 (30 girls and 30 boys) bilingual and 60 (30 girls and 30 boys) monolingual children in three age groups (mean ages 8.5, 10.5 and 12.5 years) were compared on episodic memory and semantic memory tasks. Episodic memory was assessed using subject-performed tasks (with real or imaginary objects) and verbal tasks, with retrieval by both free recall and cued recall. Semantic memory was assessed by word fluency tests. Positive effects of bilingualism were found on both episodic memory and semantic memory at all age levels. These findings suggest that bilingual children integrate and/or organize the information of two languages, and so bilingualism creates advantages in terms of cognitive abilities (including memory). Some sex differences were also found in episodic memory but not in semantic memory. This episodic memory difference was found with younger children.     

The role of executive functions in bilingual children with reading difficulties

To explore the joint effect of reading difficulties (RD) and bilingualism on executive functions, 190 children of four groups of 9–12 year‐olds (41 bilinguals with RD, 45 monolinguals with RD, 45 bilinguals without RD, and 59 monolinguals without RD) were examined on the Concentration game, Tower of Hanoi, and Stroop as measures of executive functioning tapping into inhibitory/attentional control, working memory and planning ability. The most prominent finding was that in terms of RD, the speed of performances decreased dramatically. This general decrease was more pronounced for bilingual children with RD than for their monolingual counterparts. In conclusion, the findings suggest that while bilinguals gain more from executive functions in normal reading, they lose in terms of RD. Such an outcome confirms that executive functions are essential components of both reading and bilingualism, which depending on whether reading conditions are normal or difficult will produce cognitive advantages or disadvantages. Further, it is argued that dissimilarity between the Farsi and Swedish languages may complicate handling of such a situation.     

Spatial memory and executive functions in children

A computerized hidden pathway maze-learning task was used to examine the development of spatial memory and executive functions in 6- to 9-year-olds. Pathway length was manipulated to investigate the impact of increases in maze matrix size on these abilities. Analysis showed that maze matrix size (and ipso facto pathway length) and age interacted to affect executive functions but not spatial memory. Executive errors differed as a function of age on the most difficult maze. Results are discussed in terms of factors affecting the development of executive functions and spatial memory.     

Central executive involvement in children's spatial memory

Previous research with adults found that spatial short-term and working memory tasks impose similar demands on executive resources. We administered spatial short-term and working memory tasks to 8- and 11-year-olds in three separate experiments. In Experiments 1 and 2 an executive suppression task (random number generation) was found to impair performances on a short-term memory task (Corsi blocks), a working memory task (letter rotation), and a spatial visualisation task (paper folding). In Experiment 3 an articulatory suppression task only impaired performance on the working memory task. These results suggest that short-term and working memory performances are dependent on executive resources. The degree to which the short-term memory task was dependent on executive resources was expected to be related to the amount of experience children have had with such tasks. Yet we found no significant age-related suppression effects. This was attributed to differences in employment of cognitive strategies by the older children.     

The p factor in children: Relationships with executive functions and effortful control

Lower levels of self-regulation have been implicated in multiple psychological disorders. Despite conceptual overlap (broadly reflecting self-regulatory functions), executive functions (EF) and effortful control (EC) are rarely jointly studied in relation to broadband psychopathology. The present study investigated associations of correlated factors (internalizing-externalizing) and bifactor psychopathology models with EF and EC in a large (N = 895) childhood community sample (M_age = 11.54, SD_age = 2.25). Associations between both self-regulation constructs (EF and EC) with psychopathology were largely accounted for via a general psychopathology factor. However, EC evidenced stronger associations, questioning the utility of task-based EF measures to inform self-regulatory psychopathology.     

Unity and diversity of executive functions in creativity

Increasing evidence suggests that executive functions (EFs) – a set of general-purpose control processes that regulate thoughts and behaviors – are relevant for creativity. However, EF is not a unitary process, and it remains unclear which specific EFs are involved. The present study examined the association between the three EFs, both uniquely (EF-Specific) and together (Common EF), and three measures of creativity. Participants (N = 47) completed a divergent thinking test, and self-reported their real-life creative accomplishments. A subset of participants indicated their involvement in the artistic or information technology (IT) professions. Results indicated that fluency (but not originality) of divergent thinking was uniquely predicted by working memory Updating. Better response Inhibition predicted higher number of real-world artistic creative achievements. Involvement in the artistic (versus IT) professions was associated with better Common EF, and with enhanced mental set Shifting abilities. Results demonstrate that different EFs predict creativity depending on its operational definition.     

Attentional control in early and later bilingual children

We examined differences in attentional control among school-age children who were monolingual English speakers, early Spanish-English bilinguals (who began speaking both languages by age 3), and later Spanish-English bilingual children (who began speaking English after age 3). Children's attentional control was tested using the Attention Network Test (ANT). All language groups performed equally on ANT networks; however, when controlling for age and verbal ability, groups differed significantly on reaction time. Early bilingual children responded faster on the ANT compared to both monolingual and later bilingual children, suggesting an attentional monitoring advantage for early bilinguals. These results add to evidence of advantaged cognitive functioning among bilinguals and are consistent with the possibility that children who begin speaking a second language earlier in childhood have greater advantages, due either to effects of acquiring a second language earlier or to longer duration of bilingual experience.     

The role of the executive system in visuo-spatial memory functioning

Participants were presented with a spatial sequence in which between 4 and 10 cells were highlighted. On each trial list length was unknown to the participant who was required to serially recall the last four cells. Processing of longer lists is assumed to call upon the executive system, which is thought to be involved in updating the contents of the short-term visuo-spatial store. Study 1 revealed that loading the executive system with concurrent random letter generation impaired performance on the spatial task especially recall of the early serial positions. However, contrary to expectation the degree of impairment was no greater on the longer lists, where it had been assumed that updating would be occurring. Study 2 confirmed this finding and demonstrated that relative to sequences of known length, under conditions of uncertainty when the list length was unknown, spatial recall was impaired even on short sequences. The present results support the growing consensus, which is suggestive of closer links between visuo-spatial and executive processes. However, it remains unclear whether or not updating is actually occurring on the longer sequences, and if it is, what specific executive processes are involved.     

How bilingual experience and executive control influence development in language control among bilingual children

This longitudinal study investigates whether the development in executive control and bilingual experience predicts change in language control in bilingual children. Children were tested twice over the course of 1 year, using the language‐switching paradigm and the Simon task. The participants were Japanese‐English bilingual “returnee” children (ages 7–13), who returned to their first language (L1) environment after spending some years in a second language (L2) dominant environment. Testing these children upon their return to the L1 environment allowed us to disentangle the effect of age from bilingual experience, as they experienced an increase in age but a decrease in L2 exposure over time. Children who had less L2 exposure showed smaller improvement in baseline performance when naming pictures in English (i.e., when English was relevant across all trials). Moreover, development in trials where children had to switch between languages were modulated by development in executive control. That is, children who increased their performance in the English mixed repetition trials also performed better on the executive control task over time. Thus, development in executive control modulated change in language control among bilingual children, suggesting a positive relationship between language control and executive control in children's development.     

Independent effects of bilingualism and socioeconomic status on language ability and executive functioning

One hundred and seventy-five children who were 6-years old were assigned to one of four groups that differed in socioeconomic status (SES; working class or middle class) and language background (monolingual or bilingual). The children completed tests of nonverbal intelligence, language tests assessing receptive vocabulary and attention based on picture naming, and two tests of executive functioning. All children performed equivalently on the basic intelligence tests, but performance on the language and executive functioning tasks was influenced by both SES and bilingualism. Middle-class children outperformed working-class children on all measures, and bilingual children obtained lower scores than monolingual children on language tests but higher scores than monolingual children on the executive functioning tasks. There were no interactions with either group factors or task factors. Thus, each of SES and bilingualism contribute significantly and independently to children’s development irrespective of the child’s level on the other factor.     

Impaired executive functions in subjects with frequent nightmares as reflected by performance in different neuropsychological tasks

Nightmare disorder is a prevalent parasomnia characterized by vivid and highly unpleasant dream experiences during night time sleep. The neural background of disturbed dreaming was proposed to be associated with impaired prefrontal and fronto-limbic functioning during REM sleep. We hypothesized that the impaired prefrontal and fronto-limbic functioning in subjects with frequent nightmares would be reflected at the behavioral level during waking tasks as well. 35-35 Subjects with frequent nightmares and matched controls participated in Study 1, involving an Emotional Go/NoGo, an Emotional Stroop task, and a Verbal Fluency task. Nightmare subjects exhibited longer reaction times in the Emotional Go/NoGo and Emotional Stroop tasks. Moreover, they committed more perseveration errors and showed less fluent word generation in the Verbal Fluency task. Nightmare subjects showed an overall slowing irrespective of the valence of the stimuli. While the effects of sleep quality and waking anxiety were associated to these deficits in some cases, these factors could not solely explain the difference between the two groups. In Study 2, 17 subjects with frequent nightmares and 18 controls were compared by a Color-word and an Emotional, block design Stroop task in order to avoid the slow effects of emotional interference potentially caused by previous items. Nightmare subjects were characterized by an overall slowing in the Emotional Stroop task, irrespective of the valence of the stimuli. In the Color-word Stroop task, nightmare subjects were not significantly slower in comparison with controls. Our results suggest that individuals with frequent nightmares are impaired in executive tasks involving the suppression of task-irrelevant semantic representations.     

The development of and interaction among alerting,orienting, and executive attention in children

A sex-balanced sample (N = 96) of children from age 6.5 to age 12.5 completed a modified Attention Network Test. Across these ages, we found evidence for developmental changes to alerting and executive control but stable orienting. Additionally, we found that the youngest members of our sample manifested an interaction between alerting and executive control that is opposite to that typically found in adults; a reversal that diminishes with age to achieve the adult pattern by the older end of the age range of our sample.     

Musical Training,Bilingualism, and Executive Function: A Closer Look at Task Switching and Dual‐Task Performance

This study investigated whether musical training and bilingualism are associated with enhancements in specific components of executive function, namely, task switching and dual‐task performance. Participants (n = 153) belonging to one of four groups (monolingual musician, bilingual musician, bilingual non‐musician, or monolingual non‐musician) were matched on age and socioeconomic status and administered task switching and dual‐task paradigms. Results demonstrated reduced global and local switch costs in musicians compared with non‐musicians, suggesting that musical training can contribute to increased efficiency in the ability to shift flexibly between mental sets. On dual‐task performance, musicians also outperformed non‐musicians. There was neither a cognitive advantage for bilinguals relative to monolinguals, nor an interaction between music and language to suggest additive effects of both types of experience. These findings demonstrate that long‐term musical training is associated with improvements in task switching and dual‐task performance.     

Phonotactic probability effect in nonword recall and its relationship with vocabulary in monolingual and bilingual preschoolers

The current study examined to what extent information in long-term memory concerning the distribution of phoneme clusters in a language, so-called long-term phonotactic knowledge, increased the capacity of verbal short-term memory in young language learners and, through increased verbal short-term memory capacity, supported these children’s first and second language vocabulary acquisition. Participants were 67 monolingual Dutch and 60 bilingual Turkish–Dutch 4-year-olds. The superior recall of nonwords with high phonotactic probability compared with nonwords with low phonotactic probability indicated that phonotactic knowledge was supportive for verbal short-term recall in both languages. The extent of this support depended on prior experiences with the language: The Turkish–Dutch children showed a greater phonotactic probability effect in their native language Turkish compared with their Dutch peers, and the monolingual Dutch children outperformed the bilingual Turkish–Dutch children in their native language Dutch. Regression analyses showed that phonotactic knowledge, indicated by the difference in recall of nonwords with high versus low phonotactic probability, was an important predictor of vocabulary in both languages.     

The interaction between emotion and executive control: Comparison between visual,auditory, and tactile modalities

The reciprocal connections between emotion and attention are vital for adaptive behaviour. Previous results demonstrated that the behavioural effects of emotional stimuli on performance are attenuated when executive control is recruited. The current research studied whether this attenuation is modality dependent. In two experiments, negative and neutral pictures were presented shortly before a visual, tactile, or auditory target in a Simon task. All three modalities demonstrated a Simon effect, a conflict adaptation effect, and an emotional interference effect. However, the interaction between picture valence and Simon congruency was found only in the visual task. Specifically, when the Simon target was visual, emotional interference was reduced during incongruent compared to congruent trials. These findings suggest that although the control-related effects observed in the Simon tasks are not modality dependent, the link between emotion and executive control is modality dependent. Presumably, this link occurs only when the emotional stimulus and the target are presented in the same modality.     

Executive functions in children engaging in open- and closed-skilled sports

Executive functions (EFs) are an important skill set for human cognition as well as achievement and can be separated into different components (inhibition, switching, updating). To date, it remains poorly understood whether the sport type children engage in is related to differences in their EFs. Thus, in the present study, we investigated whether children with regular engagement in open- and closed-skilled sports perform differently on tasks assessing inhibition, switching, and updating skills. Cross-sectional data from 113 children aged 8–13 years was used, of those 42 children engaged exclusively in open-skilled sports (e.g., soccer), 44 engaged exclusively in closed-skilled sports (e.g., swimming), and 27 engaged in both sport types as indicated by parental report. Children took part in three computerized tasks assessing their inhibitory, switching, and updating skills. Additionally, their verbal-reasoning skills, motor abilities, and aerobic fitness were assessed using acknowledged tasks. Results showed no differences with respect to children’s inhibitory and updating skills among the groups. However, it was found that children engaged in open-skilled sports showed lower switch costs in the switching task as compared to children engaged in closed-skilled sports. Follow-up analyses demonstrated that this held particularly true for children with a high level of engagement in open-skilled sports. Our findings indicate that children with a regular participation in open-skilled sports show higher switching skills as peers with a regular engagement in closed-skilled sports, suggesting that children’s experience in a dynamic, unpredictable sport exercise may be closely related to their EFs.     

On the evolutionary origins of executive functions

In this paper it is proposed that the prefrontal lobe participates in two closely related but different executive function abilities: (1) "metacognitive executive functions": problem solving, planning, concept formation, strategy development and implementation, controlling attention, working memory, and the like; that is, executive functions as they are usually understood in contemporary neuroscience; and (2) "emotional/motivational executive functions": coordinating cognition and emotion/motivation (that is, fulfilling biological needs according to some existing conditions). The first one depends on the dorsolateral prefrontal areas, whereas the second one is associated with orbitofrontal and medial frontal areas. Current tests of executive functions basically tap the first ability (metacognitive). Solving everyday problems (functional application of executive functions), however, mostly requires the second ability (emotional/motivational); therefore, these tests have limited ecological validity. Contrary to the traditional points of view, recent evidence suggests that the human prefrontal lobe is similar to other primates and hominids. Other primates and hominids may possess the second (emotional executive functions) prefrontal ability, -but not the first (metacognitive executive functions) one. It is argued that metacognitive executive functions are significantly dependent on culture and cultural instruments. They probably are the result of the development and evolution of some "conceptualization instruments"; language (and written language as an extension of oral language) may represent the most important one. The second executive function ability (emotional/motivational) probably is the result of a biological evolution shared by other primates.