HYPNOTISM. 371 



see two footstools, and consequently two dogs. In the 

 former case, where there is no point de repere^ one of two 

 things may occur, if a prism be placed before one eye. If the 

 person sees that real objects are doubled, he may infer that 

 the dog is also doubled. If, however, he be so situated that 

 the objects really perceived are such as cannot be doubled 

 by the prism, he will not infer that the hallucination is 

 doubled (e.g. if the hallucination be that of a bird, and he 

 be looking up at a cloudless sky). 



Such a visual hallucination will, in accordance with the 

 law of association of ideas, lead to the development of 

 hallucinations of the other senses. Thus if a person see 

 an (imaginary) canary bird, he will soon hear it sing ; the 

 visual hallucination calls up, suggests, the auditory. These 

 associated hallucinations will depend on the strength of the 

 primary one. For instance, suppose a person see an (imagi- 

 nary) dog lying on the hearthrug, and attempt to stroke it, 

 the absence of tactile sensations may suffice to dispel the 

 visual hallucination ; if, however, this be strong, the person 

 will think he touches the dog, i.e. associated tactile halluci- 

 nations occur. Again, if he thinks the footstool is the dog 

 (hallucination with point de repere)^ then touching this may 

 suffice to dispel the visual hallucination ; but if this be 

 strong, the person misinterprets these, and thinks he strokes 

 the animal. 



All these hallucinations are " positive " ; i.e. the person 

 thinks he sees some object which really is not there. They 

 may, however, be negative ; i.e. in consequence of an auto- 

 suggestion, or suggestion from without, the person does 

 not perceive some object which actually is present. In- 

 stances of this are probably much more numerous in every- 

 day life than are positive hallucinations ; thus it often 

 happens that we do not see something because we think it 



