The Widespread Use of the Wechsler IQ Scale: Dangerous or Beneficial?

One of the most prominent tests used to test general intelligence is the Wechsler IQ Scale, which has been adapted to various age-dependent populations: the WAIS-IV for adults (16–90.11 years of age), the WISC-III for children (6–16 years of age) and the WPPSI-R for preschool children (4–6.5 years of age). Moreover, it is the most widely used psychological test used to date. Its plethora of applications include clinical research, educational contexts and classification, and a variety of neuropsychological studies spanning various areas of research. This is mainly because the nature of the Wechsler IQ Scale is multifaceted and tests various kinds of intelligence: verbal comprehension, perceptual reasoning, working memory and processing speed. It can also produce two scores, a “Full Scale IQ” and “General Ability Index”, and thus the scale offers more information to the tester about the testee. To spare the reader, I will not go into every subtest of the scale, as a full overview is available in class lecture slides. A benefit of this widespread use of the scale is that it may indicate the test’s validity in being able to be applied in a variety of contexts and areas of research.

However, given the many challenges of creating a validated test, especially for testing such a controversial construct such as intelligence, the systematic use of the Wechsler IQ scale can lead to systematic biases in a very wide range of scientific findings. For example, a recent finding has found concrete systematic cross-cultural differences on several subtests of the WAIS-IV as a result of syllabic demand on the Spanish version of the test. This finding, produced by López et al. (2016), led the group to conclude that more research is necessary to further investigate other cognitive factors (in addition to syllabic demand), that might contribute to performance and outcome differences on the WAIS Digit Span in Spanish-English bilinguals. It is very easy to imagine other subtle cross-cultural differences that may emerge from administering the Wechsler IQ Scale. It is even more difficult to imagine all the possible contributing factors which may effect the IQ score, which puts this scale, and the studies which use it, in a very dangerous position. Although this is a great challenge for psychological testing as a whole, the widespread use of the Wechsler IQ Scale may have a systematic effect on scientific findings. Furthermore, this systematic effect is especially important given the nature of scientific research; past findings are used as a literature review, and if one isn’t careful, they can incorporate many subtle effects into their findings and conclusions, without making an explicit and important note to future readers. This process may occur repeatedly over time, and thus, via a snowball effect, build a body of scientific research with many unexamined confounds as a result of administering this scale.

The findings from one study suggested that the WAIS discriminated the ISL (Irish Sign Language) population because some of the concepts used in the scale are not evident. Additionally, the Wechsler IQ Scale has been administered to populations with ASD, which may have unnoticed effects on scientific findings regarding this specific and unique population which is different to the normal population. A study by Bolen et al. (1995) has found a systematic difference in the scores of cognitively disabled children on the WISC-III compared to the WISC-R. A special education population is expected to score 8 points lower on average on the WISC-III compared to the WISC-R. They do note, however, that caution must be taken when considering changes in educational classification or interpreting qualitative differences in performance on the WISC-III scores compared to the WISC-R scores, in light of this finding. Thus, even a variation of the Wechsler IQ Scale, the same general scale, can lead to a significant difference in scoring. This is important because the use of one over the other Wechsler IQ Scale may have a significant difference in scoring within the same population, and thus lead to conclusions from misleading interpretations of results.

There have been many promising improvements to the Wechsler IQ Scale in order to make it more sensitive towards minorities, such as children with learning disabilities and females. However, there are still emerging discrepancies regarding the scale, and more that need to be examined and discovered. A small benefit of this systematic use of the Wechsler IQ Scale, is that the studies that have used it can be easily found and assessed as a review study. However, given the difficulties that exist in transmitting scientific research to the public, scientists must be very weary of this systematic use of a scale, which is used among a huge and varying population. This is especially important because the Wechsler IQ Scale is still producing subtle effects by a variety of cognitive factors which may cause problems in score interpretation and applications of the scale for placement and diagnosis. Because this scale is administered to such a large group of varying individuals, there is an increasing difficulty in examining all the possible influencing factors. However, if some are devoted enough, it is a great opportunity to study the vast possibility of effects on intelligence testing.

Further investigations into this issue will be critical in order to ensure the credibility of scientific research. Moreover, an interesting factor to study, in relation to intelligence scales, is that of cognitive styles and how they may effect scoring on intelligence scales. Cognitive style is used to describe the way that individuals think, perceive and remember information. Several current scales which measure cognitive style include the Myers-Briggs Type Indicator (MBTI), Cognitive Style Analysis (CSA), Embedded Figures Test (EFT), Group Embedded Figures Test (GEFT), Hudson’s Converger-Diverger construct, Driver’s Decision Style Exercise (DDSE), Complexity Self-Test Description Instrument and Allinson-Hayes Cognitive Style Index (CSI). The CSI currently stands as the most widely used measure of cognitive style in cognitive research.