Using a means-means-ends problem-solving task, this study examined whether 16-month-old walking infants (N = 28) took into account the width of a bridge as a means for crossing a precipice and the location of a handrail as a means for augmenting balance on a narrow bridge. Infants were encouraged to cross from one platform to another over narrow…

Executive function mechanisms underpinning language-related effects on theory of mind understanding were examined in a sample of 165 preschoolers. Verbal labels were manipulated to identify relevant perspectives on an explicit false belief task. In Experiment 1 with 4-year-olds (N = 74), false belief reasoning was superior in the fully and…

How and when do children develop an understanding of extraordinary mental capacities? The current study tested 56 preschoolers on false-belief and knowledge-ignorance tasks about the mental states of contrasting agents--some agents were ordinary humans, some had exceptional perceptual capacities, and others possessed extraordinary mental…

Kinematic measures of children's reaching were found to reflect stable differences in skill level for planning for future actions. Thirty-five toddlers (18-21 months) were engaged in building block towers (precise task) and in placing blocks into an open container (imprecise task). Sixteen children were retested on the same tasks a year later.…

The study explored how the meaning of prosocial behavior changes over toddlerhood. Sixty-five 18- and 30-month-olds could help an adult in 3 contexts: instrumental (action based), empathic (emotion based), and altruistic (costly). Children at both ages helped readily in instrumental tasks. For 18-month-olds, empathic helping was significantly more…

This study examined in a cross-cultural context mothers' discussions of mental states and external behaviors in a story-telling task with their 3-year-old children and the relations of such discussions to children's emotion situation knowledge (ESK). The participants were 71 European American and 60 Chinese immigrant mother-child pairs in the…

There is ongoing debate about children's ability to use subsequently acquired language to describe preverbal experiences. This issue was addressed experimentally in this investigation using a novel paradigm. Two-year-old children who lacked color words were individually taught to activate a bubble machine by selecting a particular color of bubble…

This study examined developmental trends in object and spatial working memory (WM) using heart rate (HR) to provide an index of covert cognitive processes. Participants in 4 age groups (6-7, 9-10, 11-12, 18-26, n=20 each) performed object and spatial WM tasks, in which each trial was followed by feedback. Spatial WM task performance reached adult…

Numerous studies show that children's language ability is related to false-belief understanding. However, there is considerable variation in the size of the correlation reported. Using data from 104 studies (N=8,891), this meta-analysis determines the strength of the relation in children under age 7 and examines moderators that may account for the…

In 2 studies mothers read wordless storybooks to their preschool-aged children; narratives were analyzed for mental state language. Children's theory-of-mind understanding (ToM) was concurrently assessed. In Study 1, children's (N=30; M age 3 years 9 months) ToM task performance was significantly correlated with mothers' explanatory, causal, and…

Five-year-old children categorized as skilled versus unskilled counters were given verbal estimation and number word comprehension tasks with numerosities 20-120. Skilled counters showed a linear relation between number words and nonsymbolic numerosities. Unskilled counters showed the same linear relation for smaller numbers to which they could…

The role of categorical versus associative relations in 5-, 7-, and 11-year-old children's true and false memories was examined using the Deese--Roediger--McDermott (DRM) paradigm and categorized lists of pictures or words with or without category labels as primes. For true items, recall increased with age and categorized lists were better…

Eight- to 12-month-olds might make A-not-B errors, knowing the object is in B but searching at A because of ancillary (attention, inhibitory, or motor memory) deficits, or they might genuinely believe the object is in A (conceptual deficit). This study examined how diligently infants searched for a hidden object they never found. An object was…

The prefrontal cortex modulates executive control processes and structurally matures throughout adolescence. Consistent with these events, prefrontal functions that demand high levels of executive control may mature later than those that require working memory but decreased control. To test this hypothesis, adolescents (9 to 20 years old)…