Over the past five years several studies have suggested that flooding and its analogues reduce fear in animals and in man. The literature on analogues of flooding in animals was surveyed by Baum (1970), who himself demonstrated that prevention of a conditioned avoidance response in rats extinguishes the response (Baum, 1966). The longer the duration of response prevention, the quicker the extinction of the avoidance response (Baum, 1969a). The greater the shock trauma involved in the original learning of the response, the longer the response prevention had to be before the avoidance response was extinguished (Baum, 1969b, 1970). In phobic human volunteers controlled studies showed that flooding in imagination reduced avoidance responses to rats (Hogan and Kirchner, 1967, 1968; Kirchner and Hogan, 1966), and that the technique worked more quickly than desensitization (Barrett, 1969) in improving snake phobias. An analogue of flooding—exposure in real life with response prevention—was also shown to be more effective than desensitization for the reduction of snake phobias (Strahley, 1965). Two studies found, however, that desensitization was superior to flooding for the reduction of snake phobias (Mealiea, 1967) and mouse phobias (Willis and Edwards, 1969), while in a further two reports flooding was not significantly different in effectiveness from desensitization for the reduction of snake phobias (de Moor, 1970) or stage fright (Calef and Maclean, 1970).