Advances in autonomous agent technology have resulted in the potential for implementations of multiple agents to act as psychological theories of complex social and affective phenomena. Simulating attachment behaviours in infancy provides a relatively simple starting point for this type of theory development. The presence of neurophysiological, psychological and other types of data facilitates the validation of architectural theories by constraining these architectures at multiple levels. A seven part design process is described which details how requirements are specified and how design, implementation and evaluation processes are carried out. Two competing theories are proposed, one that involves some deliberation and one that is reactive only.