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Diagnosis of
mental
defects.
Dr. Shrubsall and Dr. Williams have been considering the question of diagnosis of mental defect,
both under the Education Acts and under the Mental Deficiency Act. The legal administrative concept
is of a social character dependent upon the power of the individual to care for himself or his affairs, or to be
educated so to do. The pathological basis is defective neuronic development, either from primary or
inherited sub-normality or as a result of trauma or pathological change during the life of the individual.
The diagnosis of this, however, is inferential, depending on observation of behaviour coupled, it may
be, with evidences of such physical defects or stigmata as are commonly associated with mental defect.
The task of the certifying officer is, therefore, to determine whether the individual is fitted for his
normal environment, whether that be the nursery, the school or the world, and if he is not, whether
this is due to mental deficiency from an early age. The data available consist of the history (personal
and family) of the subject, the results of a physical examination and of a special mental examination.
The factors concerned in diagnosis are expressed in brief in the certificate which has to be given
when a petition is presented. This distinguishes between the facts observed by the medical officer in
the course of his physical and psychological examination and the information he received from others
as to the personal and family history of the subject. The fact of deficiency must be established by
interpretation of the facts observed in the light of the history ; it may be established without such
history, but can never be firmly sustained on the evidence of the latter alone. A large part of the
process of diagnosis consists in a critical estimate of the value of the subsidiary evidence put forward.
The family history is of importance as indicating a predisposition to mental defect or instability
which may be of great weight in a doubtful case, but it is important not to overweight this factor
should it conflict with actual observation. The child of a psychotic parent might be merely
backward from ill-health, malnutrition, or lack of school attendance even though he have undoubtedly
defective brothers and sisters. Personal history, including any natal and prenatal influences, is of greater
importance for diagnosis ; incidents at birth, a history of previous illnesses and accidents are essential.
Of these meningitis, hemiplegia, epilepsy and a history of syphilis are the most important.
The antecedent history is somewhat more definite in the case of those defectives who have
required to be dealt with under the Mental Deficiency Act than in those sent to special schools.
Order of birth has little significance, save that a mongol is usually the last living child in a family.
An important piece of evidence is the age at which the subject began to walk, to talk, and to
become clean in his habits, delay beyond the third year is suggestive of mental defect in the absence of
physical explanations. This serves for purposes of diagnosis in the case of young children and as
evidence of defect from an early age in the case of those of maturer years.
Extrinsic factors such as loss of schooling, change of school, out of school conditions, foreign origin
with bilingual conditions at home, previous illness or crippling which might in part account for educational
retardation, have to be noted and assessed, as have the possible factors of social inefficiency in
those beyond school age.
When a child has been in attendance at a school, it is customary to receive a full account from
the head teacher setting out the child's attainments and conduct. Formerly, this only described the
attainments in the terms of grades and standards, and in the forms now being issued, the teacher is
asked to state definite performances. The following examples have been prepared for the guidance
of the teachers :—
Reading.—The child attempted the following (or any
selected) passage. Words (or letters) not recognised
are cut out thus, [dog]. Words (or letters)
recognised with difficulty are underlined
Writing.—The child copied the following words
or, the child attempted the following letters or
words or piece from dictation (with errors
indicated).
Memory.—Give two or three examples of success or
failure.
Example.—A [dog] ran into the [road] to look
for a bone, but a cart came by and hit his
[tail.]
Example was — dog — he — went,
and failed to copy rightly :—
say — joy — kick.
Example.—Th dg ren in th wu.
The child knew his teacher's name, knew his
dog's or cat's name or baby's name.
But did not remember if it was raining hard
when he came to school, and did not remember
if he brought any lunch.
Calculation.—The child cannot count beyond (say) 7, and does not recognise (say) figure 7 or 9.
He cannot add (say) 5 and 3, cannot subtract 2 from 5; he could add 5 and 4 but not 7 and 8 ;
could subtract 2 from 5 but not 7 from 13. Knows twice times table to 2 by 4 equals 8.
Medical examination falls into two parts :—(i) Physical—In the course of the physical examination
are noted any conditions such as definite illness, malnutrition, fatigue, defects of the special senses,
adenoids and the like which might give rise to a condition of temporary retardation or spurious defi-