32 Effect of Alcohol on Psycho-Physiological Functions. 



for this initial difference in level, since the nervous organism is subject 

 to changes from experiment to experiment. It is not uncommon 1 to 

 give preliminary averages an arbitrary value of 100 each and then 

 on this basis to transpose the succeeding averages for the respective 

 periods or days into percentages. These percentages are adequate for 

 mere comparison, but they entirely obliterate the real measurement 

 unit and hide the direct appreciation of any possible difference in neural 

 level as expressed in the measured values of the first periods. In this 

 monograph it is assumed that tables of data are much more generally 

 useful if the material be stated in the original units of measurement. 

 To obtain a simplified statement of relation for two series of meas- 

 ments, it is necessary first to compute the difference between the 

 assumed normal and each of the succeeding values of a series, and to do 

 this separately for each series. The differences are obtained very 

 simply and are given in section n. Starting with the normal day 

 shown in table 2, the preliminary value of 212 <r, which we assume as 

 the reaction-time level, or "normal of the day," is deducted from 194, 

 192, and 189 a, respectively, yielding differences of -18, -20, and 

 —23 <r. The minus sign indicates that the reaction-time averages fol- 

 lowing the first hour are shorter than the average obtained in the first 

 hour, in other words, than the " normal of the day." Using the same 

 method for the alcohol day, we obtain in this instance a series of plus 

 differences—^, e., 190 <x deducted from 223, 214, and 201 <j yields +33, 

 +24, and +11 a, respectively — indicating lengthened reactions fol- 

 lowing the alcohol dose. The two series of differences which have thus 

 been found are assumed to be related to each other in somewhat the 

 same manner as the first-period value (normal of the day) is related to 

 those values which come after the alcohol or control dose. The normal 

 differences are hence deducted algebraically from the alcohol differences, 

 just as the normal of the day was subtracted from the averages for periods 

 2,3,and4of the day. For instance, from the alcohol difference +33<r for 

 period 2, one subtracts the normal difference of — 18 <r; the true differ- 

 ence which, according to the conditions of the experiment, is assumed to 

 be the effect of alcohol in this period, is therefore +51 <r. If the normal 

 differences and alcohol differences were given as two curves in a dia- 

 gram, the distance between the two curves on the ordinate for period 

 2 would obviously also be 51 a. Using the average of the relevant pre- 

 liminary values as a standard (212 and 190 <r, average, 201 <r), +51 a 

 may be conveniently expressed as +25 per cent increase in the length 

 of eye-reaction time. The effect of alcohol on the reaction times for 

 periods 3 and 4 (see table 2, section in) was found in the same way as 

 illustrated with period 2, the amounts being +44 a and +34 <r, respec- 

 tively, as " shown by differences." The average effect for all periods 

 following the dose is +43 <t. In terms of per cent the results for periods 



1 Kraepelin, Intern. Monatsschr. z. Erforschung des Alkoholismus, Oct.-Nov. 1916. 



