IQ testing in a nutshell: The basic facts, those that are often unknown


IQ tests predict educational and occupational outcomes, for which they have proven accuracy, not intelligence per se.  One should not overstate their value or meaning. 

References to support this:

Wechsler 1975; Kaufman, 1979; Kaufman, 1994; Kaufman and Lichtenberger 1999; Lichtenberger and Kaufman, 2009; Weiss et al, 2010; Kranzler et al, 2015; Abad et al, 2016

IQ tests test a small range of cognitive abilities only and as such, they miss a lot of important aspects of how people function.

References to support this:

Wechsler 1975; Gardner, 1983; Gardner 1999; Wechsler, 2008; Kaufman 2009; Stanovich 2009; Furnham et al 2012

IQ tests are not always reliable measures of intelligence. This means results can be distorted, or wrong.

References to support this:

Kaufman and Lichtenberger, 1999; Groth-Marnat at al, 2000; Chelune 2003; Wechsler, 2008; Whitaker 2008; Kaufman 2009; Gordon et al 2010; Benson et al 2010; Levin et al, 2010; Whitaker 2010; Whitaker and Wood 2010; Estevis et al 2012; McDermott et al 2014.  Chen et al 2016.  Gomez et al, 2016.

Retesting with IQ tests invariably leads to increases in the later score. These increases can be very large, especially when the first test score was very low.

References to support this:

Lineweaver and Chelune 2003; Chelune 2003; Hawkins and Tulsky 2003; Whitaker 2008; Weiss et al, 2010; Estevis et al 2012

IQ tests cannot predict with accuracy how people function in their daily lives. They do not measure social abilities, emotional behaviour or daily functioning.

References to support this:

Wechsler 1975; Kaufman and Lichtenberger 2006; Groth-Marnat, 2009; Kaufman 2009


The assessment of intelligence needs to consider other aspects of an individual’s life, and cannot rely just on the results of testing.

References to support this:

Wechsler 1975; Roid and Barram 2004; Wechsler 2008; Faguy 2012; Lechner and Rammstedt, 2015

Intelligence is more complex than the areas covered by IQ tests. Indeed, the prevailing direction of psychology is that it is made up of many areas, some of which cover personal, social and emotional issues.

References to support this:

Gardner 1983; Sternberg 1985; Goleman 1996; Austin and Saklofske 2005; Stanovich 2009; MacCann 2010; Faguy 2012; Mayer et al 2012; Qualter et al 2012



Abad F. J, Sorrel M. A, Roman F. J and Colom R. (2016).  The relationship between WAIS IV, factor index scores and educational level:  A bi-factor model approach.  Psychological Assessment.  Vol. 28. (8). pp 987 – 1000.

Austin E. J and Saklofske D. H (2005) Far too many intelligences? On the communalities and differences between social, practical and emotional intelligences. In, Roberts R D. (Ed.) Emotional Intelligence: An International Handbook. Ashland. Hogrefe and Huber.

Benson N., Hulac D. M and Kranzler J. H (2010) Independent examination of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS IV): What does the WAIS IV measure? Psychological Assessment. Vol. 22. 1. pp 121 – 130.

Chelune G. J (2003) Assessing reliable neuropsychological change. In: Franklin R. D (Ed); Prediction in Forensic and Neuropsychology: Sound Statistical Practices. LEA. London.

Chen H. Pan T and Zhu J. (2016).  It is the examinees IQ.  Psychological Assessment, February 15th first posting.

Estevis E. Basso M. R and Combs D (2012) Effects of practice on the Wechsler Adult Intelligence Scale IV across 3- and 6-month intervals. Clinical Neuropsychologist. Vol. 26. (2). Pp 239 – 254.

Faguy K (2012) Emotional Intelligence in Health care. Radiologic Technology. Vol. 83 (3), pp 237 – 253.

Furnham A, Boo H C and McClelland A (2012) Individual differences and the susceptibility to the influence of anchoring cues. Journal of Individual Differences. Vol 33 (2) pp 89 – 93

Gardner H (1983) Frames of Mind: The theory of multiple intelligences. New York. Basic Books.

Gardner H (1999) Intelligence Reframed: Multiple Intelligences for the 21st Century. New York. Basic Books.

Goleman D (1996) Emotional Intelligence: Why it can matter more than IQ. London. Bloomsbury.

Gomez R, Vance A and Watson S (2016).  Bi-factor model of WISC-IV:  Applicability and measurement in variants in low and normal IQ groups.  Psychological Assessment, September 5th first posting.

Gordon S. Duff S. Davidson T and Whitaker S (2010) Comparison of the WAIS III and WISC IV in 16 year old special education students. J. of App Research in ID. Vol. 23. pp 197 – 200.

Groth-Marnat G, Gallagher R. E, Hale J. B and Kaplan E (2000) The Wechsler Intelligence Scales. In, Groth-Marnat G (Ed.) Neuropsychological Assessment in Clinical Practice: A guide to test interpretation and integration (pp 129-194) New York. Wiley.

Groth-Marnat G (2009) Handbook of Psychological Assessment, 5th Ed’n. Hoboken. Wiley.

Hawkins K. A and Tulsky D. S (2003) WAIS (III) WMS (III) Discrepancy Analysis: Six Factor Model Index Discrepancy Base Rates, Implications and a Preliminary Consideration of Utility. In: Tulsky et al (Ed’s) Clinical Interpretation of the WAIS (III) and WMS (III). London. AP

Kaufman A. S (1979) Intelligent testing with the WISC-R. Chichester. Wiley and Sons.

Kaufman A. S (1994) Intelligent testing with the WISC-III. Chichester. Wiley and Sons.

Kaufman A.S (2009) IQ testing 101.  New York. Springer.

Kaufman A. S and Lichtenberger E. O (1999) Essentials of WAIS III Assessment. NY. Wiley and Sons.

Kaufman A. S and Lichtenberger E. O. (2006) Assessing Adolescent and Adult Intelligence. Wiley. Hoboken.

Kranzler J. H, Benson N. and Floyd R. G (2015).  Using estimated factor scores from a bi-factor analysis to examine the unique effects of the latent variables measured by the WAIS IV on academic achievement.  Psychological Assessment, Vol. 27 (4).  Pp 1402 – 1416.

Lechner C. M and Rammstedt B. (2015).  Cognitive ability, acquiescence and the structure of personality in a sample of older adults.  Psychological Assessment.  Vol. 27 (4). pp 1301 – 1311.

Levin D. S. Thurman S. K and Kiepert (2010) More than just a memory. In, Current issues in applied memory research. Ed’s. Davies G. M. and Wright D.B. Hove. Psychology Press.

Lichtenberger E. O and Kaufman A (2009) Essentials of WAIS IV Assessment. Hoboken. Wiley.

Lineweaver T. L and Chelune G. J (2003) Use of the WAIS (III) and WMS (III) in the Context of Serial Assessments: Interpreting Reliable and Meaningful Change. In: Tulsky et al (Ed’s) Clinical Interpretation of the WAIS (III) and WMS (III). London. AP

MacCann C (2010) Further examination of emotional intelligence as a standard intelligence: A latent variable analysis of fluid intelligence, crystallised intelligence, and emotional intelligence. Personality and Individual Differences. Vol. 49. (5). Pp 490 – 496.

Mayer J. D, Panter A. T and Caruso D. R (2012). Does Personal Intelligence Exist? Evidence from a new ability-based measure. Journal of Personality Assessment. Vol. 94 (2). pp 124 – 140.

McDermott P.A, Watkins M.W, Rhoad A.M (2014).  Whose IQ is it?  Assessor bias variants in high stakes psychological assessment.  Psychological Assessment.  Vol. 26 (1). pp 207 – 214.

Qualter P. Gardner K. J. Pope D. J. Hutchinson J. M. and Whiteley (2012) Ability Emotional Intelligence, Trait Emotional Intelligence, and Academic Success in British Secondary Schools: A 5 year Longitudinal Study.  Learning and Individual Differences. Vol. 22 (1). Pp 83 – 91.

Roid G. H and Barrem R. A (2004) Essentials of Stanford-Binet Intelligence Scales (SB5) Assessment. Hoboken. Wiley.

Stanovich K. E (2009) What intelligence tests miss: The psychology of rational thought. YUP. New Haven.

Sternberg R. L (1985) Beyond IQ: A triarchic theory of human intelligence. New York. CUP.

Wechsler D (1974) Wechsler Intelligence Scale for Children -Revised. New York. The Psychological Corporation.

Wechsler D. (1975) Intelligence defined and undefined: a relativistic appraisal. American Psychologist. Vol. 30 pp 135 – 139.

Wechsler D (1997) WAIS (III) test administration and scoring manual. San Antonio, TX. The Psychological Corporation.

Wechsler D (2008) WAIS IV: Technical manual. San Antonio, TX. The Psychological Corporation.

Weiss L. G, Saklofske D.H, Coalson D and Engi Raiford S (2010) WAIS IV: Clinical use and Interpretation. London. AP

Whitaker S and Wood C (2008) The distribution of scaled scores and possible floor effects in the WISC III and WAIS III. J. of App Research in ID. Vol. 21. pp 136 – 141.

Whitaker S (2008) The Stability of IQ in People With Low Intellectual Ability: An Analysis of the Literature. Intellectual and Developmental Disabilities. Vol. 46 (2). pp 120-128.

Whitaker S (2010) Error in the estimation of intellectual ability in the low range using the WISC-IV and WAIS-III. Personality and Individual Differences. Vol. 48 (5), pp 517-521.