E. B. TITCHENER— ETHNOLOGICAL TESTS OF SENSATION. 209 



the first available experimenter to make up a haphazard series of 32 

 stimuli, 16 dual and 16 single, and to perform the test upon my fore- 

 arm in AIcDougall's way. The experimenter was wholly unprac- 

 tised, so that I worked under unfavorable conditions: the time of 

 impression varied, its intensity varied, the instrument was set down 

 sometimes slowly and sometimes with impact, the ready-signal was 

 often omitted, and so forth. As a preliminary I was given four 

 stimulations, two single and two dual ; by these few experiences I 

 tried to fix in mind the difiference of the two perceptive forms. Then 

 came the series; and it turned out that I was able to judge the two- 

 point impression correctly in 11 out of its 16 appearances. That is 

 a correctness of almost 70 per cent. 



The result was encouraging — so much so that I determined to 

 repeat the trial under better conditions. A few days later, then, I 

 worked through the same series with change of order (not that I 

 should have recognized the original order!) and with proper regu- 

 lation of times and intensities and warning-signals. I now judged 

 the two-point impression correctly in 15 out of 16 cases. Since 

 McDougall's liminal value requires only 13 correct judgments,^ my 

 present limen of dual impression, calculated in his way, is some- 

 thing less than zero. I have at least equalled the performance of 

 Meiti and Tapau and Biskak.^ 



I give the series in full, since they are instructive to those familiar with 

 the aesthesiometric experiment. 



Trial I. Preliminary Stimulations, 4. 



Stim. Jdgt. Stim. Jdgt. Stim. Jdgt. Stim. Jdgt. 



2 2 I I 2 I I 2 



I I 2 2 I 2 2 2 



I 2 I I 2 2 2 I 



2 2 2 I 2 2 2 I 



2 2 I I I I 2 I 



2 2 I 2 I 2 I I 



I 2 2 2 2 2 2 2 



I 2 I I I 2 I ...I 



Summarizing we have : 



2 judged as 2 11 times i judged as i 8 times 



2 judged as i 5 times i judged as 2 8 times 



8 R, 190. 



9 R, 203 f . 



