CHAPTER IV. 



EFFECT OF ALCOHOL ON FREE ASSOCIATIONS. 1 



The highest complication of the reflex arc with which we felt justified 

 in dealing in this research is that which is commonly known as the free- 

 association experiment, and this would not have been attempted had 

 it not been for the generous collaboration of an expert in the field. 



METHODS AND APPARATUS. 



As it is commonly practiced, the association experiment is a kind of 

 reaction. The stimulus to reaction is a word spoken by the operator . 

 The reaction is a response word spoken by the subject. The kind of 

 response which is demanded of the subject may be systematically 

 varied, giving rise to several different types of association experiments. 

 In the free-association experiment the subject is required merely to 

 speak as quickly as possible the first word that occurs to him after the 

 stimulus word is given. 



The relationship between the stimulus word and the response, 

 together with the latency of the reaction word, are the usual significant 

 facts in the experiment. In addition, the so-called psycho-galvanic 

 reflex and the accompanying pulse-changes have been regarded as 

 significant. We undertook to measure all these factors. 



The free-association experiment occupied the balcony of the psy- 

 chological laboratory (see p. 30). The subject reclined in a steamer- 

 chair and faced a bare corner of the room. Behind the subject and to 

 his right the operator (Wells) sat at a small, properly illuminated 

 writing-table, on which were the switches for the various electric 

 currents, a 2-volt signal light, and the operator's reaction key. 2 



The device for securing pulse-records 3 was attached to the left wrist 

 of the subject. A light but sensitive pneumograph capsule was but- 

 toned under his vest. Electrodes for securing the psycho-galvanic 

 reflex rested on a suitable stand at the subject's right hand, so that the 

 index and second digit of his right hand could reach them with the 

 arm in a natural and comfortable position. 



APPARATUS FOR THE PSYCHO-GALVANIC REFLEX. 



The apparatus which was used for measuring the psycho-galvanic 

 reflex was : (1) non-polarizable electrodes for the fingers : (2) a Wheat- 

 stone bridge which was connected as though to measure the skin- 

 resistance against a variable, known resistance; and (3) a string galva- 

 nometer connected across the bridge. The electrodes were the same 



*In collaboration with Dr. F. L. Wells, of McLean Hospital, Waverly, Mass. 



2 See figure 21, facing page 101. 



3 A complete description of this device is given in Chapter VIII, p. 189. 



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