Written for PSYC6211, June 2009.

IQ: incomplete, questionable

In popular usage, IQ has come to mean something very different than a measure of one’s academic aptitude. The population at large seems to overestimate the application of “IQ” in the same way they underestimate the scientific utility of a “theory.” What, exactly, does IQ measure?

The first standardized intelligence tests appeared just after the turn of the 20th century. At the request of the French government, researchers Binet and Simon developed the first reliable test of general intelligence. This test, intended to identify children who might need additional instruction and to moderate the bias of teacher assessments, became quite popular. By 1916, Stanford theorists introduced the scoring system we now know as the intelligence quotient (IQ), or the relationship between a child’s mental age and chronological age (Weiten, 2008). As a predictor of general scholastic achievement, IQ functions reasonably well, with a positive correlation of .65 with academic achievement (Weiten).

Beyond its intended purpose, however, the utility of the intelligence quotient wanes. While IQ can predict success, it does not explain why any given person may be successful. While it can identify children in need of supplemental instruction, it does not highlight what kind of help they require. During the 1980s, newer models of intelligence emerged as Sternberg identified three different skills sets of intelligence: verbal, practical, and social (Weiten, 2008) and Gardner posited seven modes of intelligence. Building on this idea of divided functionality, but moving into a more measurable framework, Naglieri & Das introduced the planning, attention, simultaneous, and successive (PASS) model of cognition and a Cognitive Assessment System (CAS) instrument to measure the PASS processes (Naglieri & Rojahn, 2004). Unlike general intelligence models, PASS identifies specific cognitive skills, including the physiological residence for each (Das, 2002).

Figure from Dass, 2002.

Planning
Planning, aka “the executive function,” resides in the brain’s frontal lobe. Planning skills apply to decision making, problem solving, and understanding the big-picture (Das, 2002).

Attention
Also known as arousal, attention is the ability to choose where to focus and what to ignore. While the attention function is difficult to pinpoint, it is likely that arousal first works in the brainstem, followed by frontal lobe involvement in directing attention (Das, 2002).

Simultaneous
The ability to see the whole and categorize its parts simultaneously is believed to reside in the cortex and in the occipital and parietal lobes (Das, 2002).

Successive
This processing skill allows filtration and ordering of stimuli into a specific and more manageable order via the frontal and temporal lobes (Das, 2002).

The testing instrument of the PASS model, the CAS, measures cognitive processes in normal, advanced, or regressed children aged 5 to 17 and in adults with reading difficulty and/or mental retardation (Das, 2002). Unlike the most widely used IQ test, the WISC-III — which measure ability within a context of expected explicit knowledge — the CAS emphasizes ability removed from the context of academic achievement (Naglieri & Rojahn, 2004). The test avoids achievement-driven questions, giving a clearer picture of actual ability (Naglieri, De Lauder, Goldstein, & Schwebech, 2006) with most of the bias from social background removed. And, in multiple comparative studies, the CAS has more strongly correlated with acheivement as measured by the Woodcock-Johnson Tests of Achievement. In a 2006 paper, Naglieri and his colleagues presented a consistent .80 correlation between the CAS and the WJ-III, compared with only a .65 correlation between the most-used general IQ test and the WJ-III (Naglieri, De Lauder, Goldstein, & Schwebech, 2006).

Not only does the CAS have a higher level of validity, it is also more useful than the traditional tests of general intelligence. For most people, scores across the four cognitive abilities are fairly well aligned. In his 2002 paper, Das presented findings that children with ADD showed significant drops planning and attention skills, while testing normal on other measures. This implies a possible diagnostic utility for the CAS. In another case, a post-auto-accident 12-year-old boy tested normally on traditional IQ measures, even as his performance at school plummeted. The CAS revealed that while this boy’s simultaneous and successive scores were normal (100 and 110), his planning and attention scores had dropped through the floor (73 and 79). Understanding which portions of a child’s cognitive abilities have declined can not only allow for better educational assistance, but also can direct doctors to possible areas of brain damage.

Like any instrument, the CAS is not perfect. I’d love to see a version of this test geared toward normal and advanced-level adults. The CAS provides much more data than other tests, but it still does not give a window into “rational quotient,” a concept Stanovich (2009) explores in his new book. But, while offering predictive value, the CAS also provides an understanding of specific cognitive abilities — an understanding that will certainly inform future areas of intelligence research.

References

Das, J. (2002). A better look at intelligence. Current Directions in Psychological Science, 11(1), 28. Retrieved June 23, 2009, from Academic Search Premier database.

Naglieri, J., De Lauder, B., Goldstein, S., & Schwebech, A. (2006). WISC-III and CAS: Which correlates higher with achievement for a clinical sample?. School Psychology Quarterly, 21(1), 62-76. Retrieved June 23, 2009, from PsycARTICLES database.

Naglieri, J., & Rojahn, J. (2004). Construct Validity of the PASS Theory and CAS: Correlations With Achievement. Journal of Educational Psychology, 96(1), 174-181. Retrieved June 23, 2009, from PsycARTICLES database.

Stanovich, K. E., (2009). What intelligence tests miss: The psychology of rational thought. New Haven: Yale University Press.

Weiten, W. (2008). Psychology: Themes and variations. Briefer version. (7th ed.). Belmont, California: Thomson Higher Education.