Bilingual infants excel at foreign‐language talker recognition

Bilingual and monolingual infants differ in how they process linguistic aspects of the speech signal. But do they also differ in how they process non‐linguistic aspects of speech, such as who is talking? Here, we addressed this question by testing Canadian monolingual and bilingual 9‐month‐olds on their ability to learn to identify native Spanish‐speaking females in a face‐voice matching task. Importantly, neither group was familiar with Spanish prior to participating in the study. In line with our predictions, bilinguals succeeded in learning the face‐voice pairings, whereas monolinguals did not. We consider multiple explanations for this finding, including the possibility that simultaneous bilingualism enhances perceptual attentiveness to talker‐specific speech cues in infancy (even in unfamiliar languages), and that early bilingualism delays perceptual narrowing to language‐specific talker recognition cues. This work represents the first evidence that multilingualism in infancy affects the processing of non‐linguistic aspects of the speech signal, such as talker identity.     

Laterality of the frontal aslant tract (FAT) explains externalizing behaviors through its association with executive function

We investigated the development of a recently identified white matter pathway, the frontal aslant tract (FAT) and its association with executive function and externalizing behaviors in a sample of 129 neurotypical male and female human children ranging in age from 7 months to 19 years. We found that the FAT could be tracked in 92% of those children, and that the pathway showed age‐related differences into adulthood. The change in white matter microstructure was very rapid until about 6 years, and then plateaued, only to show age‐related increases again after the age of 11 years. In a subset of those children (5–18 years; n = 70), left laterality of the microstructural properties of the FAT was associated with greater attention problems as measured by the Child Behavior Checklist (CBCL). However, this relationship was fully mediated by higher executive dysfunction as measured by the Behavior Rating Inventory of Executive Function (BRIEF). This relationship was specific to the FAT—we found no relationship between laterality of a control pathway, or of the white matter of the brain in general, and attention and executive function. These findings suggest that the degree to which the developing brain favors a right lateralized structural dominance of the FAT is directly associated with executive function and attention. This novel finding provides a new potential structural biomarker to assess attention deficit hyperactivity disorder (ADHD) and associated executive dysfunction during development.     

Bilingual toddlers’ comprehension of mixed sentences is asymmetrical across their two languages

In bilingual language environments, infants and toddlers listen to two separate languages during the same key years that monolingual children listen to just one and bilinguals rarely learn each of their two languages at the same rate. Learning to understand language requires them to cope with challenges not found in monolingual input, notably the use of two languages within the same utterance (e.g., Do you like the perro? or ¿Te gusta el doggy?). For bilinguals of all ages, switching between two languages can reduce the efficiency in real‐time language processing. But language switching is a dynamic phenomenon in bilingual environments, presenting the young learner with many junctures where comprehension can be derailed or even supported. In this study, we tested 20 Spanish–English bilingual toddlers (18‐ to 30‐months) who varied substantially in language dominance. Toddlers’ eye movements were monitored as they looked at familiar objects and listened to single‐language and mixed‐language sentences in both of their languages. We found asymmetrical switch costs when toddlers were tested in their dominant versus non‐dominant language, and critically, they benefited from hearing nouns produced in their dominant language, independent of switching. While bilingualism does present unique challenges, our results suggest a united picture of early monolingual and bilingual learning. Just like monolinguals, experience shapes bilingual toddlers’ word knowledge, and with more robust representations, toddlers are better able to recognize words in diverse sentences.     

Early executive functioning in a global context: Developmental continuity and family protective factors

This study extends the methodological and theoretical understanding of executive functions (EFs) in preschoolers from low‐ and middle‐income countries (LMIC). First, the authors describe a rigorous process of adapting and evaluating six EF tasks to produce a culturally and developmentally appropriate measure of emerging EFs in a large sample of at‐risk children in rural Pakistan. Next, the authors identify critical developmental and family factors that relate to preschoolers’ EFs over the first 4 years of life. Direct assessment of children's general cognitive skills at age two showed developmental continuity with EFs at age four, and these early cognitive skills mediated the effect of an antecedent parenting intervention on EFs as well as associations of targeted individual and family factors with EFs. Furthermore, directly assessed maternal cognitive capacities and observed maternal scaffolding uniquely predicted EFs in preschoolers. This study is also the first to demonstrate a significant overlap between direct assessments of IQ and EFs in young children from LMIC. Children's general intelligence mediated the associations of EFs with antecedent physical growth and cognitive skills as well as concurrent family factors (maternal verbal intelligence, maternal scaffolding, and home stimulation). After controlling for shared variance between preschoolers’ general intelligence and EFs, three factors emerged as unique predictors of EFs: exposure to an early parenting intervention, physical growth status at age two, and number of older siblings. The findings have important implications for the design of interventions that aim to improve EFs in young children in LMIC. A video abstract of this article can be viewed at https://vimeo.com/316329544/5abde94cd7     

The vocabulary spurt predicts the emergence of backward semantic inhibition in 18‐month‐old toddlers

The current study examines the relationship between 18‐month‐old toddlers’ vocabulary size and their ability to inhibit attention to no‐longer relevant information using the backward semantic inhibition paradigm. When adults switch attention from one semantic category to another, the former and no‐longer‐relevant semantic category becomes inhibited, and subsequent attention to an item that belongs to the inhibited semantic category is impaired. Here we demonstrate that 18‐month‐olds can inhibit attention to no‐longer relevant semantic categories, but only if they have a relatively large vocabulary. These findings suggest that an increased number of items (word knowledge) in the toddler lexical‐semantic system during the “vocabulary spurt” at 18‐months may be an important driving force behind the emergence of a semantic inhibitory mechanism. Possessing more words in the mental lexicon likely results in the formation of inhibitory links between words, which allow toddlers to select and deselect words and concepts more efficiently. Our findings highlight the role of vocabulary growth in the development of inhibitory processes in the emerging lexical‐semantic system.     

Age-related changes in word retrieval vary by self-reported anxiety but not depression symptoms

Tip-of-the-tongue states (TOTs) are known to increase in frequency across adulthood, but there is wide variability in older adults’ TOT rates, suggesting that individual difference factors contribute to TOT incidence. We investigated the role of affect by examining the relationship between self-reported anxiety and depression symptoms and the frequency of TOTs during a laboratory task. Participants were young, middle-aged and older adults in a population-based sample of adults aged 18–87. Increased anxiety was associated with fewer TOTs for the middle-aged group but more TOTs for the older adult group. There was no relationship between anxiety and TOTs for younger adults and no relationships between depression symptoms and TOT incidence for any age group. We discuss our results in terms of attentional control theory, which provides an explanation of how age may affect the relationship between anxiety and TOTs.     

Specific effects of the Trier Social Stress Test on speech fluency in young and older adults

The notion that speech becomes less fluent during stressful speaking conditions has received little empirical test, and no research has tested this relationship in older adult participants. We analyzed speeches produced during the Trier Social Stress Test (TSST) or during a less stressful placebo (pTSST) version of the task. We measured young and older adults’ speech fillers (e.g., um), unfilled pauses (at least 1 s in duration), and other disfluencies (e.g., repetitions, repairs). Neither young nor older adult participants rated themselves as having greater stress in the TSST than pTSST condition, but behavioral effects were obtained. Participants in the TSST condition produced more mid-phrase speech fillers and unfilled pauses than participants in the pTSST condition. Young adults produced more unfilled pauses than older adults overall, and older adults produced more mid-phrase fillers than young adults. Critically, age group interacted with experimental condition, such that older speakers produced disproportionately more mid-phrase fillers than young adults in the TSST compared to the pTSST condition. In sum, the negative effects of the TSST on fluency were generally similar across age, but this specific age-related increase in mid-phrase fillers indicates that older adults’ word retrieval may have been particularly negatively affected. Findings are generally consistent with previous research and add to understanding of how factors internal to the speaker (i.e., demographic, personality, and cognitive variables) and factors external to the speaker (i.e., variables regarding the situation, context, or content of speech) combine to affect speech fluency.     

Linking property crime using offender crime scene behaviour: A comparison of methods

This study compared the ability of seven statistical models to distinguish between linked and unlinked crimes. The seven models utilised geographical, temporal, and modus operandi information relating to residential burglaries (n = 180), commercial robberies, (n = 118), and car thefts (n = 376). Model performance was assessed using receiver operating characteristic analysis and by examining the success with which the seven models could successfully prioritise linked over unlinked crimes. The regression‐based and probabilistic models achieved comparable accuracy and were generally more accurate than the tree‐based models tested in this study. The Logistic algorithm achieved the highest area under the curve (AUC) for residential burglary (AUC = 0.903) and commercial robbery (AUC = 0.830) and the SimpleLogistic algorithm achieving the highest for car theft (AUC = 0.820). The findings also indicated that discrimination accuracy is maximised (in some situations) if behavioural domains are utilised rather than individual crime scene behaviours and that the AUC should not be used as the sole measure of accuracy in behavioural crime linkage research.