Conceptions of Learning and the Study of Life Span Development: A Symposium / Roles of the Operant Model and Its Methods in the Life Span Approach to Human Development / A Learning Theory Critique of the Operant Approach to Life Span Development / Learning and Development: Mutual Bases in a Dialectical Perspective / A Dialectic Analysis of Learning Theory Contributions to Understanding Human Development / Information Processing, Knowledge Acquisition and Learning: Developmental Perspectives