Cooperative Competence in Infancy: The Role of Mothers, First Impressions, and the Cooperative Phenotype in Shaping Infants' Development

Abstract

Cooperation, or the ability to coordinate one’s actions and attention to attain a shared goal, is an integral part of human life. While much is known regarding the developmental trajectory of cooperation across the first two years of postnatal life, few studies have examined the environmental and biological factors that support this development. Additionally, little is known regarding how socio-cognitive characteristics, thought to support cooperative exchanges, and cooperative performance correlate to explain infants’ cooperative competence. The studies presented in this thesis address these gaps in the literature by utilising data from an ongoing longitudinal study (N = 255) to examine how: 1) ma-ternal personality and cooperative values contribute to 14-month-old infants’ cooperative ability with an unfamiliar adult (Chapter Two), 2) the quality of an initial social inter-action between two 23-month-old children impacts their future cooperative performance (Chapter Three), and 3) measures of 23-month-olds’ cooperative understanding, ability, motivation, and social interaction quality, obtained during cooperative exchanges with an unfamiliar adult, converge and correlate with one another to form a cooperative phenotype (Chapter Four). The results revealed that infants of mothers high in personality traits associated with adult cooperation, or who had other-oriented cooperative values, demonstrated enhanced cooperative ability with an unfamiliar adult at the age of 14-months; however, this effect was not mediated by temperament (i.e., biology) or at home cooperative social gameplay (i.e., socialisation). When participating in a cooperative ex-change with a same-aged, same-sex peer at the age of 23 months, infants’ display of friendly and supportive social behaviours towards their peer during the first 90 seconds of an introductory warm-up period was associated with cooperative motivation during the following cooperative exchange. However, when 23-month-olds participated in a co-operative exchange with an unfamiliar adult, social interaction quality behaviours and motivation did not bolster cooperative outcomes. Instead, 23-month-olds’ ability to understand shared goals (i.e., show cooperative understanding) was correlated with their cooperative ability, suggesting that when 23-month-olds cooperate with an adult, their physical ability to fulfil their cooperative role and their ability to understand shared goals plays a critical role in fostering cooperative competence. Taken together, the findings and unique methodological and statistical approaches used in this thesis provide novel insights into the processes underlying early cooperative development.