Joint attention (JA) is the purposeful coordination of an individual's focus of attention with that of another and begins to develop within the first year of life. Delayed, or atypically developing, JA is an early behavioural sign of many developmental disabilities and so assessing JA in infancy can improve our understanding of trajectories of…

It is known that infant-directed speech (IDS) plays a key role in language development. Previous research, however, has also identified significant variability across societies in terms of how often IDS occurs. For example, some studies report very little IDS in non-western, small-scale societies -- including children growing up in small-scale…

Prior work showed that infants look longer at impossible figures than possible ones, although it is unclear whether they or older children understand "impossibility." We employed a series of matching and sorting tasks with pictures and objects to evaluate children's knowledge of this dimension. In Experiment 1, nearly all children…

Maternal singing is considered vital to infant well-being. This study focuses on vocal emotion expressions in infant-directed singing among mothers in war conditions. It examines the questions: (a) how traumatic war events and mental health problems are associated with the content and valence of vocal emotion expressions and (b) how these emotion…

In this study, we address the construction of the first symbolic uses of objects in contexts of triadic interaction (adult-child-object). We assume that symbolic productions are based on public rules of the use of objects previously agreed by the community. The first symbols are not rooted in any literal, evident reality, but in shared rules of…

Two studies with 9-, 11- and 13-month-old infants were conducted to investigate infants' ability to use an object's material properties to guide their object-directed actions. In study 1, 9- and 11-month-old infants played in an exploration phase with two objects made of different materials, one very heavy and the other one light and playable.…

The current study examined the influence of maternal characteristics on the development of infant smiling and laughter, a marker of early positive emotionality (PE) and how maternal characteristics and the development of infant PE contributed to subsequent maternal parenting. One hundred fifty-nine mothers with 4-month-old infants participated.…

Self-produced locomotion is regarded as a setting event for other developmental transitions in infancy with important implications for socioemotional development and parent-child interaction. Using an age-held-constant design, this study examined changes in reported infant behaviour and maternal proactive/reactive control and compared them with…

Three-month-old Cameroonian Nso farmer and German middle-class infants were compared regarding learning and retention in a computerized mobile task. Infants achieving a preset learning criterion during reinforcement were tested for immediate and long-term retention measured in terms of an increased response rate after reinforcement and after a…

The purpose of the current study was to investigate the development of sleep-wake and melatonin diurnal rhythms over the first 3 months of life, and the potential effect of bed-sharing on their development. It was hypothesized that increased maternal contact through bed-sharing would affect the development of rhythms in human infants. Ten…

Previous work by our group has shown that infant emotional vitality (EV), the lively expression of shared emotion both positive and negative, predicts cognitive and language abilities in toddlerhood. Specifically, infants who demonstrated a pattern of high emotional expression combined with high bids to their caregivers, fared significantly better…