Tuesday, October 6, 2009

Psychological tests II

New tests are checked for reliability, to ensure that comparable results would be obtained by different observers or on different occasions. The most important characteristic of a test procedure is its validity.

Validity is concerned with questions such as: what is this test actually measuring? does this test give a true measure of the child's abilities in this particular area? what deductions can be made from the results? and do these results imply that the child has a problem which can be expected to interfere with future progress and prospects?

In general, any assessment of a young child should be regarded primarily as a measure of current functioning, a method of quantifying what the child has learnt up to the present moment. Prediction of future progress or ultimate intel­lectual potential from measures made in early childhood is unwise, unless the child's abilities are repeatedly found to be in the severely learning-disabled range. Many factors contribute to the difficulties of prediction, including the intrinsic deficiencies of the test; variations in the skill of the tester; anxiety, shyness, lack of motivation or undiagnosed hearing loss in the child; and unusual patterns or temporary setbacks in devel­opment.

The tester has to make a subjective judgement of the extent to which these factors might invalidate the results. Also, since the child's ultimate abilities depend to some extent on experi­ences yet to come, it is intrinsically unlikely that one could predict their future on the basis of their performance in the first few years of life.

Several studies have shown that by 2Vi years of age there begins to be some correlation between the test scores and later intelligence. The ability of an IQ. score to predict academic and career progress increases throughout childhood. In the majority of children IQ_ is a surprisingly stable quantity; significant and occasionally dramatic changes can occur, but these are exceptional. Furthermore, it is not possible to predict how a particular life event or experience will affect the IQ of an individual child. Most children will tend to seek activities and environments in which they feel most comfortable, so that their intellectual powers are not encouraged to grow; but a few may deliberately engage in tasks which stretch their capacity and perhaps increase their IQ as a result.

Tests available to doctors

The Griffiths test is the most readily available formal test for the paediatrician. It is a standardized scale for chil­dren aged 0—8 years. It requires a special test kit, which is only supplied when a training period has been completed. The results are presented as a developmental profile. The doctor who can use only this test is at a definite disadvantage compared with the psychologist, who can select the most appropriate procedure from an extensive repertoire. Furthermore, some aspects of this test are open to criticism on technical grounds. In particular, the construction of the test does not allow easy separation of language from non-verbal items.

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