4 JOSEPH U. Y ARE ROUGH 



order of the presented series as it was recollected. He saw the 

 series but once. Obviously, only the visible series gave a basis 

 for comparison, and in these Bigham found that for the simul- 

 taneous series the percentage of error for the five subjects ran : 

 13.6, 9.8, 15.3, 17.9, and 15. In the successive series the cor- 

 responding percentages of error were 18.5, 23.3, 16.6, 24.1, and 

 21.6. The averages for the two series were 14.3 percent and 

 20.8 percent for the simultaneous and the successive, respectively. 

 Hence, he concludes: "With each observer the memory was 

 stronger for the simultaneous than for the successive presenta- 

 tions." 



Bergstrom 4 (1907) performed a series of experiments pat- 

 terned after the work of Ebbinghaus. Three subjects were each 

 required to memorize 12 lists of nonsense syllables, 12 syllables 

 to the list, for each of four days. Each syllable was exposed to 

 view for a period of 820-, and a given time interval was allowed 

 to elapse between the successive exposures of the syllables. The 

 syllables were to be pronounced but once at the time of exposure, 

 and after four repetitions of a list a recall test was given. In 

 this test a written reproduction was made and the amount memo- 

 rized was gauged by the number of errors made. The intervals 

 between the exposures were 3O2er, 6860-, and 1454^, and the 

 average number of errors was, respectively, 10.3, 8.9, and 7.5. 

 By increasing the interval between exposures the number of er- 

 rors was decreased. This fact is at variance with the assump- 

 tion that a nervous impression begins to fade soon after it is 

 received and gradually dies away, and must be explained by the 

 greater strength either from the clearer original impressions or 

 perhaps by other factors which are favored by a longer time 

 interval. 



Again, 30 subjects were used by this same experimenter, and 

 lists of 10 words and lists of 10 letters, presented orally at a 

 metronome-controlled rate, were used as material. The time 

 intervals between presentations here were .5, i, and 2 seconds. 

 One presentation was made for each list, and the errors made in 



4 Bergstrom, J. A., Amer. Journ. PsychoL, Vol. XVIII, pp. 206-238. 



