Alternative Test 2: Repeating Three Digits Reversed
PROCEDURE. The digits used are: 2-8-3; 4-2-7; 5-9-6. The test should be
given after, but not immediately after, the tests of repeating digits
Say to the child: "_Listen carefully. I am going to read some numbers
again, but this time I want you to say them backwards. For example, if I
should say 1-2-3, you would say 3-2-1. Do you understand?_" When it is
evident that the child has grasped the ins
ructions, say: "_Ready now;
listen carefully, and be sure to say the numbers backwards._" Then read
the series at the same rate and in the same manner as in the other
digits tests. It is not permissible to re-read any of the series.
If the first series is repeated forwards instead of backwards series
exhort the child to listen carefully and to be sure to repeat the
SCORING. The test is passed if _one series out of three_ is repeated
backwards without error.
REMARKS. The test of repeating digits backwards was suggested by
Bobertag in 1911, but appears not to have been used or standardized
previous to the Stanford investigation.
It is very much harder to repeat a series of digits backwards in the
direct order at year VII, and six at year X. Reversing the order places
three digits in year VII, four in year X, five in year XII, and six in
"average adult." Even intelligent adults sometimes have difficulty in
repeating six digits backwards, once in three trials.
As a test of intelligence this test is better than that of repeating
digits in the direct order. It is less mechanical and makes a much
heavier demand on attention. The digits must be so firmly fixated in
memory that they can be held there long enough to be told off, one by
Feeble-minded children find this test especially difficult, perhaps
mainly because of its element of novelty. School children are often
asked to write numbers dictated by the teacher, and even the very dull
acquire a certain proficiency in doing so; but the test of repeating
digits backwards requires a certain facility in adjusting to a new task,
exactly the sort of thing in which the feeble-minded are so markedly
As a rule the response consumes much more time than in the other digits
test. This is particularly true when the series to be repeated backwards
contains four or more digits. The chance of success is greatly increased
if the subject first thinks the series through two or three times in the
direct order before attempting the reverse order. The subject who
responds immediately is likely to begin correctly, but to give the first
part of the original series in the direct order. For example, 6-5-2-8 is
Sometimes the child gives one or two numbers and then stops, having
completely lost the rest of the series in the stress of adjusting to the
novel and relatively difficult task of beginning with the final digit.
In such cases the feeble-minded are prone to fill in with any numbers
they may happen to think of. A good method for the subject is to break
the series up into groups and to give each group separately. Thus,
6-5-2-8 is given 8-2 (pause) 5-6. As a rule only the more intelligent
subjects adopt this method. One 12-year-old girl attending high school
was able to repeat eight digits backwards by the aid of this device.
It would be well worth while to investigate the relation of this test to
imagery type. Such a study would have to make use of adult subjects
trained in introspection. It would seem that success might be favored by
the ability to translate the auditory impression into visual imagery, so
that the remembered numbers could be read off as from a book; but this
may or may not be the case. At any rate, success seems to depend largely
upon the ability to manipulate mental imagery.
The degree of certainty as to the correctness of the response is usually
much less than in repeating digits forwards.