CHAPTER V
RAPIDITY OF LEARNING SERIES OF SYLLABLES AS A FUNCTION
OF THEIR LENGTH
Section 19. Tests Belonging to the Later Period
It is sufficiently well known that the memorisation of a series of
ideas that is to be reproduced at a later time is more difficult, the
longer the series is. That is, the memorisation not only requires more
time taken by itself, because each repetition lasts longer, but it also
requires more time relatively because an increased number of repetitions
becomes necessary. Six verses of a poem require for learning not only
three times as much time as two but considerably more than that.
I did not investigate especially this relation of dependence, which
of course becomes evident also in the first possible reproduction of series
of nonsense syllables, but incidentally I obtained a few numerical values
for it which are worth putting down, although they do not show particularly
interesting relations.
The series in question comprised (in the case of the tests of the year
1883-84), 12, 16, 24, or 36 syllables each, and 9, 6, 3, or 2 series were
each time combined into a test.
For the number of repetitions necessary in these cases to memorise
the series up to the first errorless reproduction (and including it) the
following numerical results were found:

In order to make the number of repetitions comparable it is necessary,
so to speak, to reduce them to a common denominator and to divide them
each time by the number of the series. In this way it is found out how
many repetitions relatively were necessary to learn by heart the single
series, which differ from each other only in the number of syllables,
and which each time had been taken together with as many others of the
same kind as would make the duration of the whole test from fifteen to
thirty minutes.[1]
However, a conclusion can be drawn from the figures from the standpoint
of decrease in number of syllables The question can he asked: What number
of syllables can be correctly recited after only one reading? For me the
number is usually seven. Indeed I have often succeeded in reproducing
eight syllables, but this has happened only at the beginning of the tests
and in a decided minority of the cases. In the case of six syllables on
the other hand a mistake almost never occurs; with them, therefore, a
single attentive reading involves an unnecessarily large expenditure of
energy for an immediately following reproduction.
If this latter pair of values is added, the required division made,
and the last faultless reproduction subtracted as not necessary for the
learning, then the following table results.
|
Number of syllables
in a series
|
Number of repetitions necessary for first errorless
reproduction (exclusive of it)
|
Probable
error
|
|
7
|
1
|
|
|
12
|
16.6
|
± 1.1
|
|
16
|
30.0
|
± 0.4
|
|
24
|
44.0
|
± 1.7
|
|
39
|
55.0
|
± 2.8
|
The longer of the two adjoining curves of Fig. 6 illustrates the regular
course of these numbers with approximate accuracy for such a small number
of tests. As Fig. 6 shows, in the cases examined, the number of repetitions
necessary for the memorisation of series in which the number of syllables
progressively increased, itself increases with extraordinary rapidity
with the increase in number of the syllables.
At first the ascent of the curve is very steep, but later on it appears
to gradually flatten out. For the mastery of five times the number of
syllables that can be reproduced after but one reading -- i.e.,
after about 3 seconds over 50 repetitions were necessary, requiring an
uninterrupted and concentrated effort for fifteen minutes.
The curve has its natural starting point in the zero point of the
co-ordinates. The short initial stretch up to the point, x=7, y=1, can
be explained thus: in order to recite by heart series of 6, 5, 4, etc.,
syllables one reading, of course, is all that is necessary. In my ease
this reading does not require as much attention as does the 7-syllable
one, but can become more and more superficial as the number of
syllables decreases.
Section 20. Tests Belonging to the Earlier Period
It goes without saying that since the results reported were
obtained from only one person they have meaning only as related to him.
The question arises whether they are for this individual of a general
significance -- i.e., whether, by repetition of the tests at
another time, they could be expected to show approximately the same
amount and grouping.
A series of results from the earlier period furnishes the desired
possibility of a control in this direction. They, again, have been
obtained incidentally (consequently uninfluenced by expectations and
suppositions) and from tests made under different conditions than those
mentioned. These earlier tests occurred at an earlier hour of the day
and the learning was continued until the separate series could be
recited twice in succession without mistake. A test comprised
|
|
15
|
series
|
of
|
10
|
syllables
|
each,
|
|
or
|
8
|
"
|
"
|
13
|
"
|
"
|
|
or
|
6
|
"
|
"
|
16
|
"
|
"
|
|
or
|
4
|
"
|
"
|
19
|
"
|
"
|
So, again, four different lengths of series have been taken into
account, but their separate values lie much closer together.
Since the repetitions -- which are in question here -- were not
counted at all in the earlier period, their number had to be
calculated from the times. For this purpose the table on p. 31 has been
used after corresponding interpolation. If the numbers found are
immediately reduced to one series each, and if along with it the two
repetitions representing the recitation are subtracted as above, we
obtain:

The smaller curve of Fig. 6 exhibits graphically the arrangement of
these numbers. As may be seen, the number of repetitions necessary for
learning equally long series was a little larger in the earlier period
than in the later one. Because of its uniformity this relation is to be
attributed to differences in the experimental conditions, to
inaccuracies in the calculations, and perhaps also to the increased
training of the later period. The older numbers fall very close to the
position of the later ones, and -- what is of chief importance -- the
two curves lie as closely together throughout the short extent of their
common course as could be desired for tests separated by 3 1/2 years
and unaffected by any presuppositions. There is a high degree of
probability, then, in favor of the supposition that the relations of
dependence presented in those curves, since they remained constant over
a long interval of time, are to be considered as characteristic for the
person concerned, although they are, to be sure, only individual.
Section 21. Increase in Rapidity of Learning in the
Case of Meaningful Material
In order to keep in mind the similarities and differences between
sense and nonsense material, I occasionally made tests with the
English original of Byron's "Don Juan." These results do not
properly belong here since I did not vary the length of the amount to
be learned each time but memorised on each occasion only separate
stanzas. Nevertheless, it is interesting to mention the number of
repetitions necessary because of their contrast with the numerical
results just given.
There are only seven tests (1884) to be considered, each of which
comprised six stanzas. When the latter, each by itself, were learned
to the point of the first possible reproduction, an average of 52
repetitions (P.E.m = ± 0.6) was
necessary for all six taken together. Thus, each stanza required
hardly nine repetitions; or, if the errorless reproduction is
abstracted, scarcely eight repetitions.[2]
If it is born in mind that each stanza contains 80 syllables (each
syllable, however, consisting on the average of less than three
letters) and if the number of repetitions here found is compared with
the results presented above, there is obtained an approximate
numerical expression for the extraordinary advantage which the
combined ties of meaning, rhythm, rhyme, and a common language give to
material to be memorised. If the above curve is projected in
imagination still further along its present course, then it must be
supposed that I would have required 70 to 80 repetitions for the
memorisation of a series of 80 to 90 nonsense syllables. When the
syllables were objectively and subjectively united by the ties just
mentioned this requirement was in my case reduced to about one-tenth of
that amount.
Footnotes
[1] The objection might be made
that, by means of this division, recourse made directly to the
averages for the memorising of the single series, and that in this way
the result of the Fourth Chapter is disregarded. For, according to that,
the averages of the numbers obtained from groups of series could
indeed be used for investigation into relations of dependence, but the
averages obtained from separate series could not be so used. I do not
claim, however, that the above numbers, thus obtained by division, form
the correct average for the numbers belonging to the separate series, i.e.,
that the latter group themselves according to the law of errors. But the
numbers are to be considered as averages for groups of series, and,
for the sake of a better comparison with others -- a condition which in
the nature of the case could not be everywhere the same -- is made the
same by division. The probable error, the measure of their accuracy, has
not been calculated from the numbers for the separate series but from
those for the groups of series.
[2] For the sake of
correct evaluation of the numbers and correct connection with possible
individual observations please note p. 24, 1. In order to procure
uniformity of method the stanzas were always read through from
beginning to end; more difficult passages were not learned separately
and then inserted. If that had been done, the times would have been
much shorter and nothing could have been said about the number of
repetitions. Of course the reading was done at a uniform rate of speed
as far as possible, but not in the slow and mechanically regulated
time that was employed for the series of syllables. The regulation of
speed was left to free estimation. A single reading of one stanza
required 20 to 23 seconds.