Toddlers' intrinsic motivation to return help to their benefactor

Applicability and usefulness of pupillometry in the study of lexical access. A scoping review of primary research

Pupil dilation has been associated with the effort required to perform various cognitive tasks. At the lexical level, some studies suggest that this neurophysiological measure would provide objective, real-time information during word processing and lexical access. However, due to the scarcity and incipient advancement of this line of research, its applicability, use, and sensitivity are not entirely clear. This scoping review aims to determine the applicability and usefulness of pupillometry in the study of lexical access by providing an up-to-date overview of research in this area. Following the PRISMA protocol, 16 articles were included in this review. The results show that pupillometry is a highly applicable, useful, and sensitive method for assessing lexical skills of word recognition, word retrieval, and semantic activation. Moreover, it easily fits into traditional research paradigms and methods in the field. Because it is a non-invasive, objective, and automated procedure, it can be applied to any population or age group. However, the emerging development of this specific area of research and the methodological diversity observed in the included studies do not yet allow for definitive conclusions in this area, which in turn does not allow for meta-analyses or fully conclusive statements about what the pupil response actually reflects when processing words. Standardized pupillary recording and analysis methods need to be defined to generate more accurate, replicable research designs with more reliable results to strengthen this line of research.

Evidence for a developmental shift in the motivation underlying helping in early childhood

We investigated children's positive emotions as an indicator of their underlying prosocial motivation. In Study 1, 2-, and 5-year-old children (N = 64) could either help an individual or watch as another person provided help. Following the helping event and using depth sensor imaging, we measured children's positive emotions through changes in postural elevation. For 2-year-olds, helping the individual and watching another person help was equally rewarding; 5-year-olds showed greater postural elevation after actively helping. In Study 2, 5-year-olds' (N = 59) positive emotions following helping were greater when an audience was watching. Together, these results suggest that 2-year-old children have an intrinsic concern that individuals be helped whereas 5-year-old children have an additional, strategic motivation to improve their reputation by helping.

Young children show negative emotions after failing to help others

Self-conscious emotions, such as guilt and shame, motivate the adherence to social norms, including to norms for prosociality. The relevance of an observing audience to the expression of negative self-conscious emotions remains poorly understood. Here, in two studies, we investigated the influence of being observed on 4- to 5-year-old children's (N = 161) emotional response after failing to help someone in need and after failing to complete their own goal. As an index of children's emotional response, we recorded the change in children's upper body posture using a motion depth sensor imaging camera. Failing to help others lowered children's upper body posture regardless of whether children were observed by an audience or not. Children's emotional response was similar when they failed to help and when they failed to complete their own goal. In Study 2, 5-year-olds showed a greater decrease in upper body posture than 4-year-olds. Our findings suggest that being observed is not a necessary condition for young children to express a negative self-conscious emotion after failing to help or after failing to complete their own goal. We conclude that 5-year-olds, more so that 4-year-olds, show negative emotions when they fail to adhere to social norms for prosociality.

Paying it forward: The development and underlying mechanisms of upstream reciprocity

Two studies investigated the development and motivations underlying children's upstream reciprocity. In Study 1, 3- and 4-year-olds (n = 40 per age group) received or did not receive help while playing a game. Subsequently, children could share stickers with a new child. The 4-year-olds, but not the 3-year-olds, showed evidence of upstream reciprocity: Those who had received help were more generous toward the new child. Study 2 (N = 46) replicated the results with 4-year-olds and found evidence for a gratitude-like motivation underlying the upstream reciprocity: Children who received help evaluated the benefactor more positively, and positive evaluations of the benefactor correlated with children's upstream reciprocity. Thus, upstream reciprocity emerges by 4 years of age and may already be motivated by a gratitude-like mechanism.

The Development of Prosocial Emotions

Humans rely heavily on their prosocial relationships. We propose that the experience and display of prosocial emotions evolved to regulate such relationships through inhibiting individual selfishness in service of others. Two emotions in particular serve to meet two central requirements for upholding prosociality: gratitude motivates maintenance of ongoing prosocial interactions, and guilt motivates repair of ruptured prosocial interactions. We further propose, and review developmental evidence, that nascent forms of these two emotions serve their respective functions from early in ontogeny. The remarkably early emergence of these prosocial emotions allows even very young children to participate in and benefit from prosociality. We discuss the implications of and challenges to this conclusion and identify pressing future directions for this work.