Infants’ pointing frequency is a predictor of their later language abilities. Yet, predictors of pointing frequency in the first year of life are not well understood. Study 1 explored what factors in infants and caregivers at 10 months would predict the pointing frequency of infants at 12 months (N = 35). Infant‐driven predictors were infants’ fine‐motor skills and point‐following abilities. Caregiver‐mediated predictors were caregivers’ pointing frequency and responsiveness toward infants’ pointing. Relevant caregiver responsiveness at 10 months predicted infants’ pointing frequency at 12 months, controlling for the other factors and infants’ prior pointing frequency. Study 2 explored whether child‐level factors influence caregivers’ responsiveness (N = 49). We examined the hand shape of infants’ pointing (whole‐hand versus index‐finger) and the presence of point‐accompanying vocalizations. Infants’ vocalization‐accompanied points were more likely to elicit relevant responses from caregivers, while hand shapes played a less pronounced role. Together, the findings reveal an early emerging mutual relationship between infant pointing and caregiver behavior such that certain characteristics of infant pointing predict caregivers’ responsiveness, and relevant responsiveness toward infants’ pointing predicts the increase in infants’ pointing frequencies.

Fourteen-month-olds selectively imitated a sub-efficient means (illuminating a lightbox by a head-touch) when this was modeled by linguistic ingroup members in video-demonstrations. A follow-up study with slightly older infants, however, could replicate this effect only in a video-demonstration context. Hence it still remains unclear whether infants' apparent tendency to be selective in learning opaque manners of novel skills from linguistic ingroup members is, indeed, a characteristic constraining property of cultural knowledge transmission that can be reliably manifested in live demonstration contexts that are more representative of naturalistic learning environments. To answer this question, we aimed to replicate the original study using live demonstration with a group of older infants (N = 48; 28 females). We found that eighteen-month-olds imitated the opaque manner of sub-efficient means action as a function of whether the demonstrator was a speaker of their own language. In a no-demonstration control group, infants relied on the self-discovered efficient means (handaction), just like infants observing the foreign speaker. These findings suggest that selectivity in learning sub-efficient opaque actions from linguistic ingroups has evolved to support transmission of culturespecific manner of action practices shared within social groups.Humans are unique in their capacity to acquire and faithfully transmit culturally shared action routines. Given their cognitively opaque and arbitrary characteristics, while acquiring such customary, normative and sub-efficient action routines, naïve learners mostly rely on demonstrations by knowledgeable others . As shown by previous research, ostensive communicative signals (e.g., establishing eye contact and being addressed by infant directed speech) have a special role in aiding infants' acquisition of cognitively opaque information , 2009Gergely, Egyed, & Király, 2007). Ostensive signals facilitate infants' learning about the functions of novel tools despite the opacity of their demonstrated manner of operation and the manifested function served by the novel artifacts (Futó, Téglás, Csibra, & Gergely, 2010). They also help infants to form novel means-actions representations (Hernik & Csibra, 2015), highlight the hidden dispositional properties of objects (

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The decoy effect is a violation of rationality that occurs when the relative preference between two target options changes with the addition of a third option, called the decoy, that is no better than the target options but worse than one of the options on one attribute. The presence of the decoy increases the chance that the option that dominates it on this attribute is chosen over the other target option. The current study tested decoy effects with great apes' food preferences. We presented apes with two target items, grape and banana, and a third item, the decoy, which was either a smaller grape or a smaller piece of banana. We found that apes' decisions were not influenced by the presence of a decoy. In general, apes did not increase their choices in favor of the target item that dominated the decoy. This would indicate that great apes are not vulnerable to the cognitive biases that cause decoy effects in humans, at least in cases where choice is between two different types of food. We discuss what can be concluded about the psychological causes of human irrational choices and their evolutionary origin.

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