Naïve chicks do not prefer objects with stable body orientation, though they may prefer behavioural variability

Domestic chicks (Gallus gallus domesticus) have been widely used as a model to study the motion cues that allow visually naïve organisms to detect animate agents shortly after hatching/birth. Our previous work has shown that chicks prefer to approach agents whose main body axis and motion direction are aligned (a feature typical of creatures whose motion is constrained by a bilaterally symmetric body plan). However, it has never been investigated whether chicks are also sensitive to the fact that an agent maintains a stable front–back body orientation in motion (i.e. consistency in which end is leading and which trailing). This is another feature typical of bilateria, which is also associated with the detection of animate agents in humans. The aim of the present study was to fll this gap. Contrary to our initial expectations, after testing 300 chicks across 3 experimental conditions, we found a recurrent preference for the agent which did not maintain a stable front–back body orientation. Since this preference was limited to female chicks, the results are discussed also in relation to sex diferences in the social behaviour of this model. Overall, we show for the frst time that chicks can discriminate agents based on the stability of their front–back orientation. The unexpected direction of the efect could refect a preference for agents’ whose behaviour is less predictable. Chicks may prefer agents with greater behavioural variability, a trait which has been associated with animate agents, or have a tendency to explore agents performing “odd behaviours”

Infants learn enduring functions of novel tools from action demonstrations

According to recent theoretical proposals, one function of infant goal attribution is to support early social learning of artifact functions from instrumental actions, and one function of infant sensitivity to communication is to support early acquisition of generic knowledge about enduring, kind-relevant properties of the referents. The current study tested two hypotheses, derived from these proposals, about the conditions that facilitate the acquisition of enduring functions for novel tools during human infancy. Using a violation-of-expectation paradigm, we show that 13.5-month-old infants encode arbitrary end states of action sequences in relation to the novel tools employed to bring them about. These mappings are not formed if the same end states of action sequences cannot be interpreted as action goals. Moreover, the tool–goal mappings acquired from infant-directed communicative demonstrations are more resilient to counterevidence than those acquired from non-infant-directed presentations and, thus, show similarities to generic representations rather than episodic ones. These findings suggest that the acquisition of tool functions during infancy is guided by both teleological action interpretation mechanisms and the expectation that communicative demonstrations reveal enduring dispositional properties of tools

A multilab study of bilingual infants: Exploring the preference for infant-directed speech

From the earliest months of life, infants prefer listening to and learn better from infant-directed speech (IDS) compared with adult-directed speech (ADS). Yet IDS differs within communities, across languages, and across cultures, both in form and in prevalence. This large-scale, multisite study used the diversity of bilingual infant experiences to explore the impact of different types of linguistic experience on infants’ IDS preference. As part of the multilab ManyBabies 1 project, we compared preference for North American English (NAE) IDS in lab-matched samples of 333 bilingual and 384 monolingual infants tested in 17 labs in seven countries. The tested infants were in two age groups: 6 to 9 months and 12 to 15 months. We found that bilingual and monolingual infants both preferred IDS to ADS, and the two groups did not differ in terms of the overall magnitude of this preference. However, among bilingual infants who were acquiring NAE as a native language, greater exposure to NAE was associated with a stronger IDS preference. These findings extend the previous finding from ManyBabies 1 that monolinguals learning NAE as a native language showed a stronger IDS preference than infants unexposed to NAE. Together, our findings indicate that IDS preference likely makes similar contributions to monolingual and bilingual development, and that infants are exquisitely sensitive to the nature and frequency of different types of language input in their early environments

Human tool cognition relies on teleology

Osiurak and Reynaud's account of human tool cognition misses key element: human capacity for functional representations and teleological inferences. I argue that the teleofunctional approach accounts better for some features of human tool cognition and points to a viable candidate for the cognitive “difference-maker” behind human technological success

Acquiring sub-efficient and efficient variants of novel means by integrating information from multiple social models in preschoolers

Sub-efficient action routines often represent culture-specific conventional forms of actions that belong to the repertoire of cultural knowledge shared by a social group. Children readily acquire such sub-efficient routines from social demonstrations and often preserve them in their action repertoire despite encountering more efficient alternatives. This suggests that they can treat sub-efficient conventional forms and their efficient alternatives in a context-sensitive selective manner. We hypothesized that children may rely on their sensitivity to differentiate speakers of their own language versus a foreign language as an informative cue indicating whether the model belongs to their own cultural community and the action modeled represents shared cultural knowledge. We assessed preschoolers’ imitation following two different demonstrations. The first model demonstrated a sub-efficient action sequence, whereas the second model presented a more efficient alternative to obtain the same goal. We varied whether the children had heard the models speak their own language or a foreign language before their nonverbal action demonstrations. We found that 4-year-olds adopted the second model’s efficient alternative, but only when she spoke their own language. However, they disregarded the efficient alternative if it was presented by a foreign-language speaker and continued to perform the sub-efficient routine they initially acquired. Therefore, 4-year-olds employed the cue of shared language to optimize acquiring and maintaining culturally shared sub-efficient action routines by selectively updating their action repertoire relying on their language-based evaluation of the demonstrator’s culture-specific competence. In contrast, 5- and 6-year-olds adopted the efficient alternative independently of the demonstrator’s language. Possible reasons for this developmental trend are discussed

The development of gaze following in monolingual and bilingual infants: A multi-lab study

Determining the meanings of words requires language learners to attend to what other people say. However, it behooves a young language learner to simultaneously attend to what other people attend to, for example, by following the direction of their eye gaze. Sensitivity to cues such as eye gaze might be particularly important for bilingual infants, as they encounter less consistency between words and objects than monolinguals, and do not always have access to the same word learning heuristics (e.g., mutual exclusivity). In a pre-registered study, we tested the hypothesis that bilingual experience would lead to a more pronounced ability to follow another’s gaze. We used the gaze-following paradigm developed by Senju and Csibra (2008) to test a total of 93 6–9 month-old and 229 12–15 month-old monolingual and bilingual infants, in 11 labs located in 8 countries. Monolingual and bilingual infants showed similar gaze-following abilities, and both groups showed age-related improvements in speed, accuracy, frequency and duration of fixations to congruent objects. Unexpectedly, bilinguals tended to make more frequent fixations to onscreen objects, whether or not they were cued by the actor. These results suggest that gaze sensitivity is a fundamental aspect of development that is robust to variation in language exposure