Welcome to the final installment of my deep dive into the IQ.  We have already looked at the first four components:  Verbal Comprehension, Visual Spatial, Fluid Reasoning and Working Memory.

Today’s post will examine Processing Speed.  As a reminder, I’ve been using the WISC-V for the basis of these posts.  The WISC-V is a cognitive assessment for children ages 6-16.  However, the WIAT-IV, which is used for adults 17 and older, also has a Processing Speed index.  The subtests used to obtain the Processing Speed index are almost identical on both assessments.

What is Processing Speed?

When describing Processing Speed in my reports, I write:

Processing Speed measures the speed and accuracy of visual identification, decision making, and decision implementation. 

There are three key components of this statement:  1) visual identification, 2) decision making, and 3) decision implementation.  Simply put, processing speed involves the ability to identify the task at hand, recognize the decision that needs to be made, and make the decision.

Students who excel at processing speed are able to work quickly on cognitive and academic tasks.  Usually they are among the first students to finish a test or to complete homework assignments.  Determining a student’s processing speed gives us insight into how efficiently he or she is able to complete such tasks.  As we’ll see below, however, students who work quickly may also experience other variables that contribute to their speed, some that aren’t necessarily positive.

How is it Calculated?

The Processing Speed index score is calculated using two subtests:  Coding and Symbol Search.  This is true for both the WISC-V (for children and adolescents) and the WAIS-IV (for adults).

The Coding subtest requires the student to view a series of numbers written in rows on a page.  The student then draws a corresponding symbol under each number.  The student is given two minutes to complete as many symbols as possible. The student is awarded one point for each correctly drawn symbol.  The student is not penalized for incorrect symbols.

The Symbol Search subtest displays one or two symbols (depending on the age of the student) on the left hand side of the page.  The student then must determine whether that symbol appears in a series of symbols displayed on the right side of the page.  If the symbol appears, the student circles it.  If not, the student checks the “No” box.  The student has two minutes to complete as many items as possible.  The student is then awarded one point for each correct answer but loses a point for each incorrect answer.

Once the two subtests are completed and scored, the score is then converted to a standard score that can be interpreted.  The Processing Speed index score can be interpreted using the following scale:

  • 130 or above: Very Superior
  • 120-129: Superior
  • 110-119: High Average
  • 90-109: Average
  • 80-89: Low Average
  • 70-79: Borderline
  • Below 70: Extremely Low

What Does the Score Tell Us?

The Processing Speed index score gives us a good idea of how quickly and efficiently a student can work on tasks involving decision making.  Essentially, the higher the processing speed score, the more likely the student is able to work at a fast pace.

I vividly remember a game our fourth grade teacher used to play with us.  It involved simple multiplication problems and was meant to reinforce our multiplication tables and math fluency.  The game worked like this:

Two students would start off by standing up.  The teacher would say a multiplication problem (i.e., 6×8), and the first student to answer correctly would continue standing, while the other student would sit back down.  Then the next student in line would stand up and compete against the winner of the first math problem.  And so on, and so on, until every student went through.

When it was my turn to stand up and compete against my peer, I remember feeling nervous, like I was in a high-stakes stand off.  As soon as the teacher said the problem, my mind began racing for the answer.  I have always had a pretty strong ability to answer math problems quickly, and I usually won at least a couple of rounds.  And this, in a nutshell, is processing speed.

Students who have strong processing speed usually finish tasks quickly and efficiently, while those with slow processing speed often take longer and sometimes require extended time.  It is important to note, however, that students sometimes work quickly despite not having the best processing speed.  There may be several explanations for such a tendency, but one of the most common relates to ADHD.

Not surprisingly, ADHD and processing speed are highly correlated, bot positively and negatively.  Students with inattentive tendencies often struggle to process information efficiently, as they become easily distracted or simply don’t hear the input consistently.  In these instances, providing accommodations in the form of extended time or a reduced-distraction environment for tests allows them to complete tasks at a rate more conducive to their ability.

On the flip side, students who struggle with impulsivity often times blurt out answers without fully considering their answer choices.  I’ve seen many impulsive students work way too fast for their own good, which leads to careless mistakes.  It can be frustrating for these kids, as they want to work quickly due to their impulsivity, but their processing speed may not keep up with that desire.  In these instances, I work with kids on how to slow down and pace themselves at an appropriate rate.  It can be challenging to accept this, but once students do, they usually experience greater academic achievement and reduced response control difficulties.

I hope you found this deep dive into IQs informative and helpful!  If you have any questions, please contact me at my email address!