Gottlieb used naturalistic observations of normally occurring events in the life history of individuals for the purpose of discovering the role of experience in the development of species-typical behaviors. His research revealed the impact of self-generated experiences (particularly those experiences that were self-stimulated) in the establishment of the universality of developmental traits. Some examples are described that highlight the differences between the direct (self-stimulative) and indirect influences (eliciting changes in the social and physical environment) of self-generated experience on the developmental progression of species-typical behavior. The development of species typical traits such as reproductive behaviors in birds and handedness in human infants is presented as examples of how self-generated experience can contribute toward the understanding of the development of behavioral traits.