In a previous article 2 the nature and development of the act of suppression with negative instruction in association tests under normal conditions are described. The object of this paper is to give the effect of alcohol and caffeine upon the power of association and reproduction as well as upon the act of suppression. Introspective data upon the process of suppression is also included. The results of the association tests with suppression in cases of dementia praecox and manic depression will

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... lso be briefly described at the close of the paper. The same conditions as in the previous experiment prevailed for these experiments. Simple pictures representing a single object were shown and the subject told to give the first word suggested by the picture. As two of the subjects figured in both series new pictures, but of the same nature as the others, were used, except in the case of the tests on the insane, where the old pictures were employed. In all 120 pictures were used, 10 of which were shown on each test day. With few exceptions a test was made every week. The previous instructions were altered so that the subjects were told not only not to name the picture, but not to name any part of it. This was found necessary because one of the subjects got 'set' to name a part of the picture. Except in the case of the insane subjects full introspection on the main period was required at all times. After the experiment had been some weeks in progress Professor Titchener's suggestion 3 in regard to introspection upon the fore-period was followed. The reaction time was taken with a 1 From the Harvard Psychological Laboratory.