can reproduce still more, and an adult still more. If we read a
sentence to children of different ages, we find that the older children
can reproduce a longer sentence. If we read a short story to children of
different ages, and then require them to reproduce the story in their
own words, the older children reproduce more of the story than do the
young children.[5]

[5] See age and sex graphs, pp. 184, 188, 189.

Girls excel boys in practically all the aspects of memory.

In rote memory, that is, memory for lists of unrelated words, there is
not much difference; but the girls are somewhat better. However, in the
ability to remember the ideas of a story, girls excel boys at every age.
This superiority of girls over boys is not merely a matter of memory. A
girl is superior to a boy of the same age in nearly every way. This is
merely a fact of development. A girl develops faster than a boy, she
reaches maturity more quickly, in mind as well as in body. Although a
girl is lighter than a boy at birth, on the average she gains in weight
faster and is heavier at twelve than a boy of the same age. She also
gains faster in height, and for a few years in early adolescence is
taller than a boy of the same age. Of course, boys catch up and finally
become much taller and heavier than girls. Similarly, a girl's mind
develops faster than the mind of a boy, as shown in memory and other
mental functions.

=The Improvement of Memory by Practice.= All aspects of memory can be
improved by practice, some aspects much, other aspects little. The
memory span for digits, or letters, or words, or for objects cannot be
much improved, but memory for ideas that are related, as the ideas of a
story, can be considerably improved. In extensive experiments conducted
in the author's laboratory, it was found that a person who at first
required an hour to memorize the ideas in a certain amount of material,
could, after a few months' practice, memorize the same amount in fifteen
minutes. And in the latter case the ideas would be better remembered
than they were at the beginning of the experiment. Not only could a
given number of ideas be learned in less time, but they would be better
retained when learned in the shorter time. If a person comes to us for
advice as to how to improve his memory, what should we tell him? In
order to answer the question, we must consider the factors of a good
memory.

=Factors of a Good Memory.= (1) The first requirement i