Modeling Infant Attachment & Exploration Behaviors Using Reinforcement Learning

How does caregiver-infant relationship impact infant locomotion exploration? Prior behavioral experiments have examined infant locomotion on its own. However, in real life, infants rarely navigate novel environments alone; therefore, infant exploration behaviors cannot be fully understood without accounting for the presence of caregivers in the environment. Prior research on Attachment Theory (AT) has highlighted the significant impact caregiver-infant relationship has on infant exploration behaviors. AT claims that different caregiver-infant relationships lead to distinct patterns of exploration in infants. Specifically, while infants with secure relationships with caregivers explore the most and the most freely, infants with insecure attachment relationships demonstrate constrained exploration. Prior computational work has used Reinforcement Learning (RL) to model infant exploration alone. More recent study has looked at infant learning through interactions with their caregiver in the environment, yet without examining how different types of infant-caregiver relationships could generate various kinds of exploration and play behaviors. The present study uses RL to train an infant agent in an environment containing toys and one of three different caregivers: loving and responsive, punishing and responsive, and loving and sometimes responsive. AT has characterized how these kinds of caregivers lead to secure and insecure caregiver-infant relationships, or attachment styles. After training, the infant agents display emergent exploration behaviors in alignment with all three expected attachment styles, but do not exhibit the kind of exploration characteristic of real infants. This work suggests that: 1) infant attachment styles can be computationally acquired from previous interaction history with the caregiver while maximizing rewards from the environment; 2) real world infants may explore the environment with additional intrinsic reward signals beyond attachment; and 3) caregiver-infant relationship modulates infant locomotion exploration and learning.