489 

 TABLE XI. O b s e r V e r R. 



Groups 



Arithm. mean 



Mean deviation 



Median 



in the first repetition : i.e. the imprinting occurred already with the 

 first repetition in groups and intervals. 



2. The rhythm of the first repetition shows almost invariably the 

 tendency to slightly accelerate in the order of the groups. With I 

 (natural method) this quickening confers a benefit on the groups as 

 well as on the intervals, both in the learning- and in the repetition- 

 experiments, though in the latter less distinctly than in the former. 

 With II (experimental method) this quickening is clearly demonstrable 

 only for the groups. In the repetition-experiments the time- values 

 of the groups and intervals are always smaller than the correspond- 

 ing values in the learning-experiments. In the first repetition the 

 experimental method is generally more favourable than the natural 

 as to consistency in the rhythm ; especially the duration of the in- 



32 



Proceedings Royal Acad. Amsterdam. XX. 



