Defining Intelligence

This page is ultimately designed to describe intelligence and its assessment.  To begin with, a moment of your time to reflect on just what it is that is being measured. What is intelligence; how is it defined?  On some level we all know what it is.  We know it when we see it, but we can’t say what we know.  Attempts to pin it down frustrate as much as they satisfy.  Here are some definitions of intelligence:

  1. Intelligence is the ability to adapt to the environment
  2. Intelligence is the ability to reason
  3. Intelligence is the ability to navigate the social world and to understand and manage others
  4. Intelligence is the ability to perceive, understand and manage emotion

The most powerful single definitional statement on intelligence comes from the creator of the most successful series of intelligence tests, David Wechsler. He defined intelligence as the “…global capacity of the individual to act purposefully, to think rationally, and to deal effectively with his environment.”  The list could be longer; much longer.  In some sense Wechsler’s definition and the other four definitions are all valid.  Each emphasizes a different aspect of intelligence….and this is just the point, there are different aspects to intelligence.  Theorists such as Robert Sternberg and Howard Gardener understood this and so they did not attempt to define intelligence globally. Instead they described types of intelligence: 
Howard Gardener describes interpersonal (relating to others), intrapersonal (knowing oneself), spatial, musical and kinesthetic intelligence, among others. Robert Sternberg, on the other hand, found three broad classes of intelligence: Analytic, creative and practical intelligence.  Truly, intelligence is brain function.  Everything we imagine intelligence to be resides somewhere in the brain.  Still, the brain does many things.  We wouldn’t want to say everything the brain does is intelligence.  We wouldn’t want to say that the ability to maintain body temperature or a regular breathing rate is intelligence; we wouldn’t want to say that vision or hearing is intelligence; we wouldn’t want to say, notwithstanding Gardener’s kinesthetic intelligence, that balance and coordination is intelligence. After eliminating these vegetative brain functions and more prosaic physical responsibilities of the brain we can list the following aspects of intelligence:

  1. Attention
  2. Reasoning
  3. Logic
  4. Visual-spatial awareness
  5. Processing
  6. Memory
  7. Knowledge

Each of these areas can be further divided into component parts.  Memory for example, can be divided into memory for faces, narrative memory, working memory, short term memory, semantic memory, declarative memory, spatial memory etcetera. Deficits can appear in global functions or in any component of a global function.  Taken together, however, these aspects of intelligence are important. They are important because together they capture what intelligence is as most of us understand it.  They are important because they enable mature social and emotional functioning.  They are important because, collectively, they enable goal directed behavior. 

Intelligence Testing

Intelligence tests are among the most potent predictors of job performance and school success. Using a standard measure of intelligence, such as the Wechsler Intelligence Scales or the Stanford Binet Intelligence Scales, provides such predictive power.  The Wechsler and Stanford Binet scales are collections of individual measures, which together assess most aspects of intelligence.  Using a battery or collection of intelligence tests provides ever more useful results.  Tests, such as a continuous performance test, measure attention over time.  Tests, such as the Wisconsin Card Sorting Task, measure learning and adaptation.  Tests, such as the NEPSY, are able to measure language fluency and various aspects of memory and learning.  A battery of such tests covers all of the above listed aspects of intelligence, providing a description of strengths and weaknesses.  Using a thoughtful collection of tests, a person’s intelligence can be meaningfully described. Read about past misuses and current controversies of intelligence testing.

Dr. Steven C. Hertler
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