Originally published in 1978, this volume provided a broad survey of the latest research and theory, at the time, concerning the potential detrimental effects of inappropriate uses of tangible rewards to modify behaviour. Overall, this research questions the dominant paradigm within which reinforcers, by definition, have positive effects on performance and subsequent behaviour, and suggests new directions for the study of human motivation. In a series of five original integrative essays, the contributors summarize their own and related research programmes. These theoretical essays are complemented by two introductory chapters, that provide a historical context for this research, and four discussion chapters, that speak to broader issues, including both the implications and limitations of the research presented. At the time, this was the latest information on a most provocative area.