Jegi—Auditory Memory Span for Numbers. 511 
to catch each child at his very best, and then to inspire him to 
do his very best to reproduce correctly the longest possible series. 
The children seemed greatly pleased with the experiment and 
expressed considerable interest in their native power of memory. 
I may safely say that these children did the best they could. 
In this way about three hundred children were tested, ranging 
in age from five to fifteen years inclusive. 
It may be of interest to say that in the beginning it was my 
purpose to test each child in the morning before school opened 
and again immediately after the close of the afternoon session 
so that the difference due to the fatigue of the regular school 
work might be taken into account. At the same time I was 
carrying on another investigation on quickness and accuracy of 
number perception using another group of school children. In 
both of these studies it was very evident from the first that the 
results were just as good at the close of the school day as at the 
beginning, and where there was a perceptible difference the 
afternoon tests were in the lead. The fatigue resulting from 
the school work seemed to have no effect whatever on the mem¬ 
ory span, or on the quickness and accuracy of number percep¬ 
tion, as revealed by the results of these two investigations. 
Most of the children, however, preferred the morning tests and 
thought that they did better in these than in the evening tests, 
and they were quite unanimous in saying that it was much easier 
in the morning. The evening tests seemed to require greater 
effort on the part of the children, but in no case were the re¬ 
sults inferior to those obtained in the morning tests. 
Results. The actual memory span as obtained in this inves¬ 
tigation is indicated on the charts and in the tables below. 
1. The reader will observe that the rate of increase in mem¬ 
ory power is practically uniform from 7 or 8 to 15 years of age, 
and that it is somewhat more rapid in the earlier years. 
2. The reader will notice further that these curves do not 
indicate that there is a time in the child’s development when 
there is a great or sudden increase in memory power, no “period 
of memory” so far as rapid growth of this power is concerned. 
3. The curve shows that the memory span increases from 4 
at the age of five to 8 at the age of fifteen, i. e., the memory span 
is doubled during the eleven years from five to fifteen. Group¬ 
ing the children as we found them in the eight grades, the in¬ 
crease is from 5.2 in the first grade to 7.9 in the eighth grade. 
