Placentation Research - Meng Hu's Blog

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HOW ACCURATE ARE IQ TESTS?
Figure 5.2 shows graphically the three children’s scores on
the five KABC-II scales and the four WISC-IV factor indexes.
Though Jason earned global IQs in the 120s, his standard
scores on the KABC-II ranged from 102 on Planning/Gf to 134
on Simultaneous/Gv, and he had about an equally large range
in his cognitive abilities on the WISC-IV (104 on WMI [Working
Memory Index] to 133 on PRI). On both tests, he displayed
his exceptional visual-spatial processing with scores in the very
superior range (above 130), which contrasted with his average
level of performance on Planning/Gf and WMI. Fluid reasoning
is dependent on the executive process of working memory—
people must maintain access to all pertinent aspects of a complex
problem on their mental scratch-pads long enough to solve
the problem correctly. Jason was relatively weak in both areas of
cognitive functioning. This is not a surprising finding in view of
research that has shown the close relationship between reasoning
and working memory; indeed, Kyllonen and Cristal (1990)
titled a seminal research article, “Reasoning Ability Is (Little More
Than) Working Memory Capacity?!” Jason also scored remarkably
consistently on both tests in his crystallized and verbal abilities
(Knowledge/Gc = 115; VCI = 114). Working memory is illustrated
FIGURE 5.2 Standard scores earned by Jason (IQs about 120), Lizzy (IQs
about 100), and Mei-I (IQs about 80) on the WISC-IV factor indexes and
the KABC-II scales.