FACTORS IN MENTAL HEALTH AND ILLNESS 573 



practise does not suffice to learn what a normal person gets with one or 

 two repetitions. Memory seems essentially unaffected in dementia 

 prcBcox and in the manic-depressive psychoses, though it may be masked 

 by confusion, apathy or stupor. These factors are mainly responsible 

 for the poorer performance in memory tests that most other pathological 

 cases show. 



Various attempts have been made to experiment with the suggesti- 

 bility of mental life, as by measuring the extent to which judgments 

 could be influenced by suggestion. Scott's ingenious experiments showed 

 that this could be different in different functions, so that we mi^ht not 

 speak of general suggestibility any more than we should speak of gen- 

 eral sensory acuity. But as an acute sense of sight would be much 

 more important for our behavior than an acute sense of smell, a rela- 

 tively great importance doubtless attaches to suggestibility in the higher 

 levels of conduct, though the level of human activity where suggestibility 

 really counts be not represented in experiments on the simpler sensory 

 and motor processes. In a sense, the distractible manic case might be 

 called over-suggestible because he catches up the examiner's interjected 

 phrases and weaves them into his talk, or is easily diverted from one 

 thing to another. But it is in the hysterical and in some dementia 

 pmcox mechanisms that suggestibility is increased to the point of giving 

 real control over conduct. The Lata of the East Indies, and the 

 Jumpers of the lumber camps are the most conspicuous examples of the 

 former. Here we see an automatic, positive response to the idea sug- 

 gested. In dementia pracox this occurs, but is not so very common. 

 The striking feature of heightened suggestibility in dementia precox 

 is that it is negative to the suggestion. Not only may the individual be 

 "blocked," as we say, making no response whatever, but so far as pos- 

 sible the opposite response may be made. It represents the extreme of 

 the "contrariness" that is met with in normal life. It even may be- 

 come possible to direct the individual's actions through asking the 

 opposite of what one wishes; but the negativism is strictly to the idea 

 conveyed. These cases know what they are about, and when it is clear 

 that the thing wished is the opposite of the thing suggested, it is no 

 longer obtained in this way. Bleuler has given a unified formulation 

 of how this symptom is related to the underlying psychosis to which 

 latter I shall subsequently allude. 



Individual differences occur in a number of mental processes more 

 involved than the above, which are but slightly subject to experiment. 

 There is no reason to suppose any specific alteration of sense imagery 

 as a result of mental disease. But those hyperfunctionings of it that 

 we call hallucinations are quite different in various mental disorders. 

 There is a delirious type of hallucination produced by poisons, like 

 alcohol, morphine and cocaine, generally visual, and not especially sys- 



