Australian children aged 6-9 years (N = 120, 71 females; data collected in 2021-2022) were tasked with remembering the locations of 1, 3, 5, and 7 targets hidden under 25 cups on different trials. In the critical test phase, children were provided with a limited number of tokens to allocate across trials, which they could use to mark target…

This study investigated the systematic rise in cognitive ability scores over generations, known as the "Flynn Effect," across middle childhood and early adolescence (7-15 years; 291 monozygotic pairs, 298 dizygotic pairs; 89% White). Leveraging the unique structure of the Louisville Twin Study (longitudinal data collected continuously…

This study examined gene-environment correlation (rGE) in intellectual and academic development in 561 U.S.-based adoptees (57% male; 56% non-Latinx White, 19% multiracial, 13% Black or African American, 11% Latinx) and their birth and adoptive parents between 2003 and 2017. Birth mother intellectual and academic performance predicted adoptive…

Two experiments were designed to investigate the developmental trajectory of children's probability approximation abilities. In Experiment 1, results revealed 6- and 7-year-old children's (N = 48) probability judgments improve with age and become more accurate as the distance between two ratios increases. Experiment 2 replicated these findings…

Despite a robust literature examining the association between sleep problems and cognitive abilities in childhood, little is known about this association in toddlerhood, a period of rapid cognitive development. The present study examined the association between various sleep problems, using actigraphy, and performance on a standardized test of…

In two experiments, one hundred and sixty-two 6- to 8-year-olds were asked to reason counterfactually about events with different causal structures. All events involved overdetermined outcomes in which two different causal events led to the same outcome. In Experiment 1, children heard stories with either an ambiguous causal relation between…

This article assessed changes in the association between single motherhood and children's verbal cognitive ability at age-11 using data from three cohorts of British children, born in 1958 (n = 10,675), 1970 (n = 8,933) and 2000 (n = 9,989), and mediation analysis. Consistent with previous studies, direct effects were small and insignificant. For…

Group membership is a strong driver of everyday life in humans, influencing similarity judgments, trust choices, and learning processes. However, its ontogenetic development remains to be understood. This study investigated how group membership, age, sex, and identification with a team influenced 39- to 60-month-old children (N = 94) in a series…

Cognitive effort is costly and this cost likely influences the activities in which children engage. Yet, little is known about how school-age children perceive cognitive effort. The subjective value of cognitive effort, that is, how valuable or costly effort is perceived, was investigated in seventy-three 7- to 12-year-olds using an effort…

This study examined future-oriented behavior in children (3-6 years; N = 193) from three diverse societies--one industrialized Western city and two small, geographically isolated communities. Children had the opportunity to prepare for two alternative versions of an immediate future event over six trials. Some 3-year-olds from all cultures…

Cognitive impairment is common among children born very preterm (VPT), yet little is known about how this risk changes over time. To examine this issue, a regional cohort of 110 VPT (= 32 weeks gestation) and 113 full-term (FT) born children was prospectively assessed at ages 4, 6, 9, and 12 years using the Wechsler Preschool and Primary Scale of…

Can children learn to select the right strategy for a given problem? In one experiment, 9- to 10-year-olds (N = 50), 11- to 12-year-olds (N = 50), and adults (N = 50) made probabilistic inferences. Participants encountered environments favoring either an information-intensive strategy that integrates all available information or an…

This study examined age differences in 299 preschoolers' responses to investigative interviewers' questions exploring the suspected occurrence of child abuse. Analyses focused on the children's tendencies to respond (a) at all, (b) appropriately to the issue raised by the investigator, and (c) informatively, providing previously undisclosed…

Infants can imitate a novel action sequence from television and picture books, yet there has been no direct comparison of infants' imitation from the 2 types of media. Varying the narrative cues available during the demonstration and test, the current experiments measured 18- and 24-month-olds' imitation from television and picture books. Infants…

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…