Child Psychology

One of the most debated topics about intelligence is how to measure it. Alfred Binet invented the first intelligence test in 1905. The French government had asked Alfred Binet to devise a way to identify those children whose intellectual abilities were so low that they would need special education. The main purpose of an intelligence test is to obtain an objective measure of a child’s intelligence in comparison with all other children of the same age and to predict a child’s future performance. Alfred Binet believed that mental ability matured as the body matured. The original Alfred Binet intelligence tests have been constantly revised. The most famous of these is the Stanford-Binet test.

The Alfred Binet intelligence test measured skills such as comprehension, judgement, reasoning and problem solving. Alfred Binet used a simple formula to give each child a score. He distinguished chronological age from mental age, which is worked out from the number of correct answers given in the subtests. To be useful IQ test scores must be reliable and valid. Test scores are reliable when they can be reproduced and are consistent. IQ test scores can be unreliable for a number of reasons. For example there might be confusing test items that could mean different things to different people. IQ tests may be too short and they do not sample adequately the abilities that we are attempting to test.

Another problem with IQ tests is that the scoring might be too subjective. A number of alternative IQ tests have been put forward to measure intelligent behaviour. These include elementary cognitive tasks, visual illusions and the Raven’s standard Progressive matrices. This last test was created to determine a person’s non-verbal intelligence. This test requires a person to identify missing elements in a series of patterns, with each pattern becoming increasingly more difficult. The test measures the ability to make sense of complex data and the ability to retain and use information.

Charles Spearman suggested that there are two types of ability in human intelligence. One is a general intelligence that is genetically inherited in varying amounts. Charles Spearman called this the g factor. The other is a set of specific abilities relating to particular tasks. Charles Spearman called this the ‘s’ factor. We would describe a person as being generally bright or dull depending on their amount of ‘g’. According to Spearman the ‘g’ factor is the most important determinant of performance on intelligence test items. All mental tests rely on the general ability, while the performance of each mental task would require a specific ability.

Charles Spearman two-factor theory seems quite reasonable. There is some kind of general intelligence in addition to specific abilities. An IQ difference of approximately 10 points between two people is not very meaningful. The person with the lower IQ but with some special, specific abilities may well perform better than the person with the higher IQ in many situations. An IQ difference of some 30 points would indicate virtually no overlap in performance. The person with the higher IQ will do better on every specific test.