Object play yields enormous benefits for infant development. However, little is known about natural play at home where most object interactions occur. We conducted frame-by-frame video analyses of spontaneous activity in two 2-h home visits with 13-month-old crawling infants and 13-, 18-, and 23-month-old walking infants (N = 40; 21 boys; 75%…

Mobile phones and other wireless devices that produce electromagnetic fields (EMF) and pulsed radiofrequency radiation (RFR) are widely documented to cause potentially harmful health impacts that can be detrimental to young people. New epigenetic studies are profiled in this review to account for some neurodevelopmental and neurobehavioral changes…

Although often conceptualized in contradictory terms, the common assumption that natural and supernatural explanations are incompatible is psychologically inaccurate. Instead, there is considerable evidence that the same individuals use both natural and supernatural explanations to interpret the very same events and that there are multiple ways in…

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…

Two studies examined how children between ages 4 and 6 use body shape (i.e., the waist-to-hip-ratio [WHR]) for sex categorization. In Study 1 (N = 73), 5- and 6-year-olds, but not 4-year-olds, selected bodies with increasingly discrepant WHRs to be "most like a man" and "most like a woman." Similarly, sex category judgments made by 5- and…

The relation between children's mental state knowledge and metaknowledge about reading was examined in 2 studies. In Study 1, 196 children (mean age = 9 years) were tested for verbal ability (VA), metaknowledge about reading, and mental state words in a story task. In Study 2, the results of Study 1 were extended by using a cross-lagged design and…

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…

The aim of this report was to investigate the prospective links between infant sleep regulation and subsequent executive functioning (EF). The authors assessed sleep regulation through a parent sleep diary when children were 12 and 18 months old (N = 60). Child EF was assessed at 18 and 26 months of age. Higher proportions of total sleep occurring…

This study investigated child compliance and maternal instruction during planning. Based on the Child Behavior Checklist and free-play observations, 40 mothers and their 4- to 5-year-old children were assigned to a group with children who behaved within the normal range of compliance (n = 20) or a group with children with high rates of…

This study describes the development of social reasoning in school-age children. An irony task is used to assess 5-, 7-, and 9-year-olds' (N = 72) and adults' (N = 24) recursive understanding of others' minds. Guttman scale analysis demonstrates that in order to understand a speaker's communicative intention, a child needs to recognize the…

This study investigated 3- and 4-year-old's understanding of the relationship between pretense and mental awareness. In Experiments 1 and 2, only a subset of 4-year-olds recognized that sleeping characters and characters ignorant of their appearance were not pretending. However, these experiments had certain linguistic demands, which potentially…

Individuals can infer what others are likely to know by clustering knowledge according to common goals, common topics, or common underlying principles. Although young children are sensitive to underlying principles, that manner of clustering might not prevail when other viable means are presented. Two studies examined how a sample of 256 children…

Although "hindsight bias" (the "I knew it all along" phenomenon) has been documented in adults, its development has not been investigated. This is despite the fact that hindsight bias errors closely resemble the errors children make on theory of mind (ToM) tasks. Two main goals of the present work were to (a) create a battery of hindsight tasks…

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…

Despite a large body of research demonstrating the kinds of categories to which infants respond, few studies have directly assessed how infants' categorization unfolds over time. Four experiments used a visual familiarization task to evaluate 10-month-old infants' (N=98) learning of exemplars characterized by commonalities in appearance or…