Two-year-olds' executive functioning: The influence of task-specific vocabulary knowledge

Complementary food exposure and children's early understanding of food words: the approaching eating through language (APPEAL) study

Introduction

Language skills, such as the ability to understand words (receptive language), develop during infancy and are built through interactions with the environment, including eating. Exposure to complementary foods also begins in infancy and may play a significant role in language development, especially in understanding of food-related words. However, the relationship between the complementary foods to which a child is exposed and early language acquisition has not been previously studied. We hypothesized that young children's food-related receptive language (FRL) would reflect the complementary foods to which they were frequently offered by caregivers.

Methods

Caregivers of young children (4-26 months; n = 408) in the Approaching Eating through Language (APPEAL) Study in the US were surveyed via Qualtrics. FRL was assessed by caregiver-report via a modified MacArthur-Bates Communicative Development Inventory. Complementary foods offered (CFO) by caregivers were assessed using a modified Food Frequency Questionnaire. Latent Class Analysis (LCA) was implemented to identify, 1) groupings of foods frequently offered (>1x/week) and 2) groupings of food-related words understood by the young children.

Results

A 5-class best fit LCA model was identified for CFO (-log likelihood [-llik]=-8727) and for FRL (-llik=-5476). Cross-classification of the CFO and FRL derived classes revealed that children with higher exposure to complementary foods were perceived by caregivers to be most likely to also understand a greater number of food-related words (Probability=0.48). As expected, children having been offered a greater number of complementary foods and who understood a greater number of food-related words were older, compared to those with less complementary food exposure and food-related language acquisition (p < 0.001).

Discussion

These findings support the potential role of introduction to complementary foods in development of food-related language.

The longitudinal contributions of child language, negative emotionality, and maternal positive affect on toddler executive functioning development

Executive functions (EF) develop rapidly across early childhood and play a prominent role in promoting adaptive outcomes later in development. Although the existing literature suggests that the development of early EF is sensitive to the influence of intrinsic and extrinsic factors, limited research has examined the joint contributions of multiple child and contextual factors in infancy/toddlerhood. The purpose of our longitudinal study was therefore to identify early environmental, behavioral, biologically-based factors that influence children's EF outcomes in late toddlerhood. Participants included 409 mother-child dyads (209 girls) and the data was collected across children's first three postnatal years. Parent-report measures were used to assess infant negative affectivity (5-months; IBQ-R) and toddler language (age 2; MCDI), and both maternal positive affect (5-months) and toddler frustration (age 2) were coded during mother-child interaction tasks. A battery of behavioral tasks was used to measure child EF in late toddlerhood (age 3). After controlling for maternal education (a proxy for children's socio-economic environment), path analysis indicated that both infant and maternal affect at 5-months directly predicted toddlers' language skills and frustration expression at age 2. Toddler language (but not frustration) also predicted child performance on multiple EF tasks at age 3. Finally, 5-month infant and maternal affect indirectly predicted age 3 EF via age 2 language. Our results identify language as a mechanism through which children's early caregiving environment influences their EF development. Taken together, these findings illustrate the importance of applying a biopsychosocial perspective to the examination of early childhood EF development.

Not all labels develop equally: The role of labels in guiding attention to dimensions

The emergence of cognitive flexibility is a central aspect of cognitive development during early childhood. Cognitive flexibility is often probed using verbal rules to instruct behavior. In this study, the types of labels that were provided during instruction were manipulated. In one condition, children were instructed in the standard manner with dimensional labels (e.g., "shape") and featural labels (e.g., "star"). In a second condition, children were provided only with dimensional labels. When switching to color, 4-year-olds performed equally well regardless of the type of instruction. However, when switching to shape, children perseverated at a significantly higher rate when only dimensional labels were provided. These results suggest that children's understanding of labels is a critical aspect of developing cognitive flexibility and that their understanding of the labels "shape" and "color" are different.

Dimensional attention as a mechanism of executive function: Integrating flexibility, selectivity, and stability

In this report, we present a neural process model that explains visual dimensional attention and changes in visual dimensional attention over development. The model is composed of an object representation system that binds visual features such as shape and color to spatial locations and a label learning system that associates labels such as "color" or "shape" with visual features. We have previously demonstrated that this model explains the development of flexible dimensional attention in a task that requires children to switch between shape and color rules for sorting cards. In the model, the development of flexible dimensional attention is a product of strengthening associations between labels and features. In this report, we generalize this model to also explain development of stable and selective dimensional attention. Specifically, we use the model to explain a previously reported developmental association between flexible dimensional attention and stable dimensional attention. Moreover, we generate predictions regarding developmental associations between flexible and selective dimensional attention. Results from an experiment with 3- and 4-year-olds supported model predictions: children who demonstrated flexibility also demonstrated higher levels of selectivity. Thus, the model provides a framework that integrates various functions of dimensional attention, including implicit and explicit functions, over development. This model also provides new avenues of research aimed at uncovering how cognitive functions such as dimensional attention emerge from the interaction between neural dynamics and task structure, as well as understanding how learning dimensional labels creates changes in dimensional attention, brain activation, and neural connectivity.