Introduction

Abstract

Operational definitions and the classification of phobic and obsessional states are discussed. Suggestions are made regarding useful parameters in measuring severity and response to therapy. Avoidance is regarded as one of the central features of phobia and its value phenomenologically and clinically is emphasised. The inadequacy of the definition of agoraphobia is stressed. The division of obsessions into rituals and ruminations and the further subdivision of rituals into those of order, cleanliness and checking is considered to be a useful classification for the purposes of measurement. The distinction between bizarre and non-bizarre obsessions is discussed.