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Previous research has suggested that infants and toddlers prioritize the imitation of goals over movements, but recent evidence revealed a more flexible pattern of imitation that depended on the visual saliency or efficiency of movements and goals. This study investigated how visual saliency of action goals alongside verbal information influences toddlers’ action processing and imitation. Twenty- to 22-month-old toddlers observed a toy animal being moved in a particular style toward one of two goals. Goals were either two-dimensional drawings or three-dimensional objects. Before the demonstration, the experimenter provided verbal information about the movement style for one group of toddlers, and about the goal for the other group. Toddlers’ imitation was influenced by goal saliency, verbal information, and an interplay of these factors. Toddlers preferred to imitate the goal over the movement in the 3D condition, and the movement over the goal in the 2D condition, revealing that goal saliency influenced imitation preferences. The effect of verbal cues depended on the order of saliency conditions. Verbal cues impacted imitation only in toddlers who participated in the 2D trials first, indicating that toddlers might be especially susceptible to verbal cues when initial visual information is less salient.

The acquisition of mental language understanding is crucial for the social-cognitive development, especially for the development of Theory of Mind reasoning. While there is evidence for the production of epistemic terms in the third year of life, the comprehension of different degrees of speaker (un-)certainty has not yet been systematically investigated at this age. In the present study, we developed an eyetracking task and measured preferential looking as an indicator of an implicit understanding of the epistemic verbs ‘know’ and ‘think’ in children aged 27 (N = 199) and 36 months (N = 131). Toddlers were faced with two agents who indicated the location of a hidden object (right vs. left box), with a narrator attributing contrasting degrees of certainty to their statements (‘know’ vs. ‘think’) before asking the toddlers about the object’s location. We measured the extent to which children fixated the box associated with the agent described as knowing where the target was and found both at 27 and 36 months of age systematic differences in their looking behaviour to this box across the trial. Children appeared to display a spontaneous preference for the box associated with the agent who knew the target’s location, relative to the agent who only thought the target was in their box in the pre-questioning phase. Subsequently, their preference switched in the post-questioning phase; however, this effect was smaller. These results indicate that toddlers in their third year of life distinguish different degrees of speaker (un-)certainty, expressed by the verbs ‘know’ and 'think'.

The COVID-19 pandemic massively changed the context and feasibility of developmental research. This new reality, as well as considerations about sample diversity and naturalistic settings for developmental research, highlights the need for solutions for online studies. In this article, we present e-Babylab, an open-source browser-based tool for unmoderated online studies targeted for young children and babies. e-Babylab offers an intuitive graphical user interface for study creation and management of studies, users, participant data, and stimulus material, with no programming skills required. Various kinds of audiovisual media can be presented as stimuli, and possible measures include webcam recordings, audio recordings, key presses, mouse-click/touch coordinates, and reaction times. An additional feature of e-Babylab is the possibility to administer short adaptive versions of MacArthur–Bates Communicative Development Inventories. Information pages, consent forms, and participant forms are customizable. e-Babylab has been used with a variety of measures and paradigms in over 12 studies with children aged 12 months to 8 years (n = 1516). We briefly summarize some results of these studies to demonstrate that data quality, participant engagement, and overall results are comparable between laboratory and online settings. Finally, we discuss helpful tips for using e-Babylab and present plans for upgrades.

Gaze following – infants’ orienting towards an object attended to by their social partner – has been linked to a range of socio-cognitive skills. Despite considerable research on when infants follow the gaze of their social partners, studies have typically examined infants’ following of adults’ gaze. Therefore, little is known about whether or how gaze following is modulated by the characteristics of the model, such as their age. The current study examined infants’ following of the gaze of an actor that varied in age: an adult, a young child, and an infant. In an eyetracking study, 49 infants, aged 6–14 months, were presented with videos in which the actor (either an adult, a child or an infant) first looked down towards a neutral point on the table, then to the participant with a friendly facial expression, and then to one of two novel objects to the left and right of the table. The age of the actor did not predict participants’ gaze following behaviour, with participants following the gaze of the adult, child and same-aged peer. Thus, gaze following is not constrained to interactions with an adult. Furthermore, participants showed high interest in the actors’ faces which was the strongest for the infant actor followed by the child actor, and the adult actor. These results shed insight into the interaction between infants’ gaze following behaviour and their attentional preferences for different social partners. We discuss the implications of these findings for theories of development: Beyond adults, other infants and children are also perceived as interesting social partners and, potentially, valuable sources of information.