SON-R Overview SON-R Overview SON-R 2.5-7 SON-R 2.5-7 SON-R 5.5-17 SON-R 5.5-17 Computerprogram SON-test Computerprogram SON-test

The SON-R 2.5-7 is an individual nonverbal intelligence test
which is suitable for children
aged from two and a half to seven years.

The test is a thorough revision of the SON 2.5-7, the 'Preschool SON', which was published in 1975.
The number of items and subtests has been increased, which resulted in a strong improvement in reliability and generalizability, especially in the more extreme age groups.

Its authors are P.J. Tellegen, J.A. Laros and M. Winkel.


The test consists of six subtests of about 15 items each.

  • The subtests Mosaics, Puzzles and Patterns involve spatial insight.
  • The subtests Categories, Analogies and Situations call upon reasoning abilities.

Separate total scores are presented for the performance scale (SON-PS) and the reasoning scale (SON-RS).

Test Administration

The nonverbal instructions and the verbal instructions are printed next to each other in the manual. Both instructions are as equivalent as possible. The most important points of the instruction are printed on the scoring form as an aid for the examiner.



The test procedure deviates from common test procedure in two ways.
  • After each item feedback is given by telling the subject whether the solution was correct or incorrect. Moreover, help is provided by the examiner when the solution is incorrect.
  • An adaptive procedure is used to prevent the administration of too many easy or too many difficult items.

It takes about 50 to 60 minutes to administer the test.




The standardization was performed using a nation-wide representative sample of 1124 children from 2;3 to 7;3 years of age. Norm tables for monthly age-groups make it possible to transform the raw subtest scores into normalized standard scores with a mean of 10 and standard deviation of 3. The total test results are represented as IQ-scores (with an 80% interval), as a percentile score, and as reference age.

Reliability and stability

The reliability of the subtests is on average .72. The reliability of the IQ-score increases somewhat with age and is on average .90.
The stability of the IQ-score (correlation test-retest) over an interval of three to four months is .79.
The correlation between SON-R 2.5-7 and the SON-R 5.5-17 over an interval of three to four months is .76.


Apart from the standardization extra validation research has been done with deaf and hearing-impaired children, children with language and speech difficulties, children with learning disabilities, autistic children and children of foreign descent. Research with the test has also been conducted with 'normal' and handicapped children in England, the USA and Australia. In total, these extra researches comprised 1500 children.
The SON-R 2.5-7 has been compared with a large number of intelligence- and language-development tests, among which the K-ABC, WPPSI-R, TONI-2, RAKIT, Bayley, McCarthy, DTVP-2, Peabody, PLS-3, Reynell, and TvK.
In the manual, information is also provided about the relation with SES, sex differences and the relation between test results and assessments by school teachers.


The Computerprogram SON-test for the calculation of standardised scores is supplied with the test.
Since December 2003 the Windows version 1.0 replaces the earlier DOS versions.
For your own use it is allowed to install this program on several computers.

After the birth date, the test date, and the raw subtest scores have been entered, the results are automatically calculated and printed.

Test Materials

The Complete Set of the SON-R 2.5-7 contains the Test materials of 5 subtests and the computer program, all packed in a wooden box.

The Manual, the subtest Patterns, and the Scoring forms have to be ordered separately.



The SON-R 2.5-7 Manual and Research Report (1998) is available in Dutch, English, German, French, Czech and Slovak languages.
Its authors are P.J. Tellegen and J.A. Laros.
From 1 October 2003 on the Manual is published by Hogrefe-Verlag, at Göttingen, Germany.


If you have any questions relating to the contents, procedures and psychometric aspects of the SON-R tests, which are not answered in these pages, please contact one of the authors:
Dr. P.J. Tellegen
or Dr. J.A. Laros.

The SON-R tests are internationally published and produced by Hogrefe Verlag at Göttingen, Germany.

If you would like to learn about prices, or order the SON-R tests, please contact one of the publishers/distributors listed below:

The Test Agency
U.K. and English speaking countries

Hogrefe Verlag Testzentrale


Czech & Slovak Republic

Hogrefe Uitgevers
The Netherlands and Belgium

Hogrefe France

The test is sold to qualified professionals only.

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