629 
was unable to know beforehand whether the stimulus, presented 
to him, was or was not one of the impressed set. 
The reaction-times of the second and the third sittings were 
registered by means of Hipp’s chronoscope; the observer, who had 
held down a Morsr-key with one of his forefingers before the 
stimulus came into view, let it go the moment he attended to the 
stimulus. The clock, which had commenced to go as the figure came 
into view, then stopped. 
The chronoscope, which was attended to prior to every sitting, 
showed for 500 control-tests distributed over 30 days a mean deviation 
of 1.35 6. 
The following table shows the distribution of the stimuli over the 
three sittings: 
PABEE I: 
Ist Sitting 2d Sitting 3d Sitting 
180 figures \ 108 objectively altered figs 108 primary figs, correspond- 
32 primary figs ing with the 108 altered figs 
40 new figs of the 2d Sitting. 
40 primary figs, belonging 
to the 32 primary figs not 
shown at the 2d Sitting. 
32 new figs. 
We failed to evoke a large number of false recognitions. Only 
in 5—7°/, of the cases did the altered figures of the 24 sitting a- 
rouse a complete or a partial false-recognition. It should be observed 
that we took into account only those cases, in which the observers 
reported unhesitatingly a recognition of entirely or partially altered 
figures. 
The following table gives for each of the three observers the 
percentage of the false recognitions compared with those of the 
cases, in which the alteration was reported determinately, or led 
to failure of recognition, or set up a sensation of novel experience. 
The last column comprises the percentages of the cases in which the 
observers could not clearly substantiate their recognition of the 
figures shown. In our calculations we started from 100 successful 
experiments with the altered figures of the 2° sitting. Owing to 
accessory circumstances — fatigue, lack of concentration ete. of the 
observers — we had to set aside for M., W, and D, respectively 
8, 8 and 13 cases, 
