DELUSIONS 91 



it is probable that what takes place is that one or several elements in the 

 present situation are like those which had been experienced in the past, 

 but that the dissimilarities in the situations are not observed. The 

 individual has a memory defect in that he parallels or identifies a com- 

 plex present experience with a similar complex past experience, although 

 in the present experience the number of elements which are the same 

 as those in the past may not be very great. In other words, the present 

 experience is deemed to be the same as that of the past because of the 

 fact that the past is not accurately remembered and properly localized 

 in time. 



Throughout all of these delusions one may discover that, in general, 

 there are two ways in which they arise. As far as can be determined, 

 Southard points out, the patients take data which are erroneous, such 

 as the lack of sensation (anesthesia) and interpret the lack of normal 

 sensation in a normal manner, viz., lack of sensation means that the 

 part is missing. By a normal individual a different interpretation may 

 be made, but the delusional interpretation is, it should be understood, 

 equally logical. We may conclude, therefore, that delusions are some- 

 times due to the fact that abnormal sensory conditions are appropriately 

 and logically interpreted. On the other hand, these delusions may also 

 arise because of abnormal or faulty methods of interpreting the data 

 which are correctly received by the patient. Thus, the woman who 

 experienced a pain due to pleurisy did not say "I have a pain in my 

 chest," but "1 have been shot in the chest." In every case it is not 

 always possible to determine whether the delusions are due to elements 

 of abnormal data or elements of abnormal reasoning. It is possible that 

 in every case both of these elements are to be found. As a rule, in those 

 who are not mentally unbalanced anesthesias and pains do not lead to 

 delusional interpretations. When the sciatic nerve has been cut in an 

 otherwise normal individual the lack of sensations which are normally 

 received from the foot and leg does not lead to the interpretation that 

 the foot or leg has been cut off or is missing. Experiences through other 

 channels of sense are added and are combined to interpret the phe- 

 nomena in a normal manner. The leg exists, but it is not felt. The lack 

 of feeling does, however, imply non-existence and this conclusion is 

 most direct. Correction of this interpretation because of sensations 

 obtained from other sources (e. g., the eye) are indirect. It is per- 

 fectly logical for the man suddenly stricken blind to believe that it has 

 suddenly become dark. It is only by an extension of experience and by 

 the utilization of other means of arriving at a conclusion that the 

 logical interpretation gives way to what may be termed a "normal" 

 interpretation. The formation of delusions as the result of abnormal 

 modes of interpretation is probably most frequent. 



