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

forwards.



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

numbers backwards.



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

one, backwards.



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

deficient.



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

given 8-2-6-5.



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.