Evolutionary Explanation in Psychology and the Development of Joint Attentional Capacities

Many psychologists are interested in the development and evolution of psychological capacities. The neo-Darwinian evolutionary paradigm serves as a metatheory in psychology, structuring evolutionary and developmental claims. These claims are often adaptationist claims, meaning psychological capacities are seen as naturally-selected adaptations and their development in individuals is causally connected to these adaptations. After Lewontin and Gould’s (1979) well-known critique of adaptationism, the problematic “strong” adaptationist explanations in the biological sciences all but disappeared. In this dissertation, I argue that evolutionary explanations in psychology are still of this problematic “strong” variety. In the following I review the claims of psychologists who study the development of early social understanding and argue that a strong adaptationist stance misconstrues the nature of psychological capacities and their development. Few psychologists recognize that the Modern Synthesis lacks a model of development, hence, problems arise when a non-developmental evolutionary metatheory inappropriately informs developmental models in psychology. I argue developmental psychologists, in spite of the current non-developmental evolutionary metatheory, can improve upon their research by shedding adaptationist assumptions and adopting a pluralistic perspective on evolutionary explanation. Joint attention is an important capacity that is often thought to be an adaptation important for the development of uniquely human capacities. I argue adaptationist-oriented researchers have insufficiently accounted for its development. I thus present two studies that examine the development of pointing and point following, two important joint attentional capacities, in human infants. In Study 1, I use parental diary data to examine the development of pointing in infants and present an account of its development which contrasts greatly with the adaptationist accounts of other joint attention researchers. In Study 2, I examine the development of point following in 9- to 12-month-old infants. I found that infants improved in point following at a steady rate and that mothers’ verbally directing infants’ attention at 9 months was predictive of infants’ point following ability between 9 and 12 months and infant language production at 12 months.