On the psycho-biological and environmental determinants of cooperative behaviors from school age children to young adults

Cooperation is a fundamental human ability that underpins our societies, manifesting in various forms from simple group projects to complex international collaborations. Defined as engaging in joint actions to achieve shared goals, cooperation requires a common objective, mutual commitment, and coordinated roles among participants. Psychological research shows that human beings are “born” cooperative, and this capacity evolves through childhood, reaching maturity by adolescence. Despite the innate tendency for cooperation, there is significant variability in its expression. This dissertation adopts a biopsychosocial framework to explore how biological, psychological, and environmental factors contribute to differences in cooperative behaviors from childhood to young adulthood. The primary aim is to investigate the interplay between biological factors (i.e., Cardiac Vagal Tone; CVT), individual (i.e., age and Environmental Sensitivity), and socio-environmental factors (i.e., family unpredictability and childhood adversities). The first two empirical chapters focus on CVT and its association with cooperative behaviors in both children and adults. Specifically, we examined whether the relationship between CVT and cooperation follows a linear or quadratic pattern and tested whether and how individual characteristics like age (Chapter 2) and environmental sensitivity (ES; Chapter 3) moderate this association. We found evidence in support of the quadratic vagal activity-prosociality hypothesis, identifying a non-linear association between CVT and cooperation. Moreover, we found that this association may depend on individual characteristics. Subsequent chapters address environmental influences on cooperation, particularly how early adolescents perceived stress (Chapter 4) and how childhood experiences (Chapter 5), such as exposure to childhood adversities and family unpredictability, impact cooperative behaviors. Results reveal that cooperation can be hindered by overwhelming stress perception. Additionally, early life experiences significantly shape cooperative dynamics. Moreover, physiological self-regulation (i.e., CVT) moderates the association between environmental factors and cooperation, such that lower levels of CVT may represent a risk factor when early adolescents are facing higher levels of perceived stress or when an individual has faced higher levels of family unpredictability. The present dissertation also explores the broader implications of cooperative behaviors on psychological outcomes (Chapter 6). It investigates the relationship between cooperation and internalizing symptoms in early and late adolescent. In contrast with the prevalent findings of research on this topic, higher levels of prosociality (i.e., taking fewer resources) were associated with greater reported internalizing symptoms in late adolescents and no association in early adolescents. Moreover, we found evidence of the moderating function of CVT on the relation between prosocial behaviors and internalizing symptoms. Overall, the findings illustrate that cooperation is influenced by a complex interplay of biological, psychological, and environmental factors. They emphasize the need for an interactional perspective when examining cooperative behavior. These insights are valuable for clinicians and educators aiming to promote effective interventions tailored to individual needs, considering the intricate determinants of cooperative behavior and its mental health implications.