How Do I Calculate My IQ?

In my last post, Can My IQ Change?, I laid out the history of the IQ test and concluded that one’s IQ can indeed change over time.

But the question remains:  How do we calculate one’s IQ?

Today’s post is the beginning of a series that will dive deeper into cognitive testing and how I use it in my evaluations.

For most clinicians, there are a few standard tests that are used in neuropsychological evaluations to derive one’s IQ.  The two most commonly used are:

·      Wechsler Intelligence Scales

·      Woodcock-Johnson

Both assessments include numerous subtests that, when put together, give an overall picture of one’s cognitive ability.  This cognitive ability is considered one’s Full Scale IQ.  I primarily use the Wechsler Intelligence Scales in my evaluations, although many clinicians prefer the Woodcock-Johnson.  Both are reliable and valid.  It really comes down to which one the clinician prefers.

For the purposes of this post, I’m going to discuss IQ in relation to the Wechsler Scales.

The Wechsler Scales come in two versions:

Ages 16-90

Wechsler Adult Intelligence Scale – 4th Edition (WAIS-IV)

Ages 6-16

Wechsler Intelligence Scale for Children – 5th Edition (WISC-V)

Since the majority of my evaluations are for children and adolescents, I will talk about the WISC-V and its various components that make up the overall IQ.

What does the WISC-V tell me?

The WISC-V is a measure of a child’s cognitive ability.  Determining one’s cognitive ability is important in a neuropsychological evaluation because it gives a baseline of what a child is capable of academically. 

There are five basic components of the WISC-V when put together give us the child’s cognitive profile.  These can be considered the five domains of the IQ.

Verbal Comprehension

Verbal Comprehension measures one’s ability to access and apply acquired word knowledge.  Tests for Verbal Comprehension include describing how two words are similar and definitions.

Visual Spatial 

Visual Spatial measures one’s ability to detect visual-spatial relationships and manipulate shapes in an appropriate manner.  In order to measure this particular ability, a child arranges blocks in a certain pattern and puts certain shapes together to form a larger shape.

Fluid Reasoning

Fluid Reasoning measures one’s ability to detect the underlying conceptual relationship among visual objects and use reasoning to identify and apply rules.  For this particular index score, the child identifies certain patterns among different pictures and determines which object can be added to a scale to balance it.

Working Memory

Working Memory measures one’s ability to take in, retain, and immediately recall small pieces of information.  Tests for Working Memory include reciting a series of numbers given audibly by the examiner and recalling certain pictures in a particular order.

Processing Speed

Processing Speed measures one’s speed and accuracy of visual identification, decision making, and decision implementation.  These tests include using a pencil to draw symbols with corresponding numbers and selecting matching pictures in one column that may or may not appear in another column, all in a timed setting.

The WISC-V gives a score for each one of these five domains.  Higher scores suggest that particular domain is an area of cognitive strength, while lower scores indicate likely areas of cognitive weakness.  When put together, one can establish an overall score, which translates into a Full Scale IQ.  It is not unusual for an individual to score higher in one or some domains in others; this just suggests that the individual has strengths and weaknesses, as most of us do.

Over the next several posts I will dive deeper into each particular domain, discussing how each impacts the learning process.  My hope is that you can begin to understand your or your own student’s unique learning profile.