Originally, the Wechsler Intelligence Scale for Children (WISC) had 12 subtests that measured only Verbal IQ, Performance IQ, and Full-scale IQ.

Then after some revisions, the verbal IQ was divided into Verbal comprehension IQ and Auditory working memory IQ, and the Performance IQ was divided into Perceptual reasoning IQ and Processing speed IQ, giving four sub-IQs (called index scores) in addition to the Full-scale IQ.

Now, on the latest revision (the WISC-V), they have subdivided the Perceptual reasoning section, so there are five sub-IQs (index scores), in addition to full-scale IQ: Verbal comprehension IQ, Auditory working memory IQ, Spatial IQ, Pure abstract reasoning IQ, and Processing speed IQ (the WISC-V refers to the Pure abstract reasoning IQ as “fluid reasoning” but that’s a bit of a misnomer because it’s no more fluid than the spatial and working memory sections; the former of which also involves reasoning).

Processing speed is the least loaded on g (general intelligence factor) and I question its relevance to an IQ test since it seems as much a measure of motor speed as intelligence. On the other hand, it seems sensitive to certain neurological impairments so that’s probably why they keep the test on.

If they would let me be a consultant on the Wechsler team, I would advise they dump the Processing speed section, and replace it with Executive function IQ, and Social IQ (Theory of Mind), both of which are impaired in autism, which is a very hot topic right now.

The term social IQ should never be confused with “emotional intelligence”, a largely pseudoscientific construct, in my humble opinion. The reason I reject “emotional intelligence” is that some tests of EQ involve impulse control and the ability to delay gratification, which strikes me as more a personality trait than a cognitive ability (though they are correlated with cognitive abilities). By contrast the term “social cognition” (Theory of Mind) refers only to the cognitive role in social interactions. Many people suck at making friends, not because they lack social cognition, but because they lack the right temperament and emotions. If an IQ test is to include social measures, it should ONLY include cognitive measures of social functioning, and leave the emotional functions to personality tests.

It’s very important to make a clear distinction between cognitive functions and emotional functions. This goes back to the most ancient philosophical understanding, which divided the mind into the intellect (that which thinks, reasons, knows and understands), and emotion (that which feels, wills and wants) Intelligence can be defined as the cognitive ability to adapt or problem solve. A problem by definition is whatever we want solved. The emotional part of the brain generates the problems, and the cognitive part (intelligence) generates solutions.

Sadly, too many psychologists today are blurring the line between cognition and emotion (assuming you believe in these concepts).