The tests provide an intelligence score that indicates how someone performs in comparison with other persons from the same age.
The first version of the SON test was developed more than seventy years ago by psychologist Nan Snijders-Oomen, to study the cognitive functioning of deaf children.
The first revision of the test was published in 1958 by Dr. Nan Snijders-Oomen and her husband, professor of Psychology Jan Snijders.
The next revisions were published under the responsibility of psychologists Peter Tellegen and Jaap Laros from the university of Groningen.
A short version of this test was published in 2007, the SON-R 2,5-7 [a], which is designed to be administered in non-western countries.
The SON-R 2,5-7 consists of six subtests that contain series of fourteen to seventeen items with increasing difficulty.
The SON-R 6-40 consists of four subtests containing two or three parallel series of twelve to thirteen items with increasing difficulty.
With the SON computer program, all standardized scores are based on the exact age of the participant.
The performance on the SON-R 2,5-7 has been compared with many cognitive tests, like the GOS, WPPSI-R, TONI-2, RAKIT, Bayley, McCarthy, DTVP-2, Peabody, PLS-3, Reynell and the TvK.
The age of the participant is important for the relation between the SON score and other measures of intelligence; the correlations are generally lower for young children than for older persons.
Because of the non-lingualism of the SON-tests, they are especially appropriate for assessing individuals with problems or handicaps in the area of language and speech development and communication and for immigrants who do not speak the language of the test leader fluently, The tests are child friendly because of their adaptive nature and the feedback that participants receive.
For the SON-R 2,5-7, standardization research has been conducted in the Netherlands, Germany, the United Kingdom, France, the Czech Republic, Slovakia and Romania.