PSYCHOLOGICAL SCIENCE 81 



studied unavailingly at night, and solved immedi- 

 ately on regaining consciousness after sleep, serves 

 as one example of this process. More striking cases 

 are shown in the phenomena of hypnotism, where 

 suggestions made by some outside person to the 

 subject during trance may affect his actions, not only 

 while in the hypnotic condition, but after recovering 

 therefrom and being apparently in a normal state 

 of self-control. Extreme instances are found in the 

 rare cases of dual or multiple personality, where an 

 injury to the brain or an unnatural sleep, or the 

 action of drugs, has resulted in complete loss of 

 memory of past life, and sometimes in the modifica- 

 tion of the old mental qualities. A return to the first 

 personality is not unknown, when forgetfulness of 

 the life of the second personality may ensue. Several 

 alternations between the two personalities have been 

 noted and described. 



Evidence has been obtained that ideas may be 

 transmitted directly from mind to mind without the 

 use of normal sense-perception, while other pheno- 

 mena affecting mind in abnormal conditions have 

 been interpreted by some observers as indicating 

 the action on living minds of consciousness associated 

 with the personalities of the dead. 



A close correspondence has been traced between 

 psychological states and changes in the nervous 

 system. Sensations are set up by the transfer of a 



nervous impulse along one set of nerves from the 



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