Memories of 100 years of human fear conditioning research and expectations for its future.

This special issue celebrates the 100th anniversary of the Little Albert study, published in February 1920, which marked the birth of human fear conditioning research. The collection of papers in this special issue provides a snapshot of the thriving state of this field today. In this Editorial, we first trace the historical roots of the field and then provide a conceptual analysis of the many ways in which human fear conditioning is currently used in theory and treatment development, with special reference to the contributions in this special issue. Ivan P. Pavlov allegedly claimed that "If you want new ideas, read old books". We could not agree more; it is our conviction that tracing the roots of our field illuminates current trends and will contribute to shaping new directions for the next 100 years of research.