What is IQ testing?
IQ testing is a method used by Clinical Psychologists to measure an individual’s intellectual capabilities in several specific domains. These domains include verbal comprehension; perceptual reasoning, working memory and processing speed. Intelligence involves the ability to think, solve problems, analyse situations, and understand social values, customs, and norms.
Two key components of intelligence include Verbal Reasoning, which is the ability to comprehend and solve language-based problems; and Nonverbal Reasoning which is the ability to understand and solve visual-spatial problems. Both these forms of reasoning are assessed using the WAIS-IV. IQ tests are good predictors of an individual’s potential for academic and occupational achievement, as well as daily adaptive functioning, however they cannot determine motivation, curiosity, creative talent or emotional intelligence.
The results of an IQ test rank the individual against a very large sample of adults the same age. If the individual scores in the top 5% for their age group it is reasonable to expect them to be performing within the top 5% academically or excelling in a vocational area. A test score below or around 70 indicates a significant limitation in intellectual functioning, and forms part of the criteria for determining an intellectual disability.
Reasons for testing?
There are common patterns in IQ testing results which can help to explain an individual’s reported cognitive difficulties. For example, a person with ADHD or a Specific Learning Disorder will often perform lower on processing speed and working memory tasks. A person with a neurocognitive disorder (e.g., Alzheimer's Disease; dementia) will also tend to perform lower on working memory and processing speed tasks. Other reasons for testing include understanding one’s cognitive strengths and weaknesses, preferred learning styles (e.g., visual-spatial versus verbal learners), or for diagnosing an intellectual disability.
The IQ test we administer for adults (age range: 16 to 90 years, 11 months) is called the Wechsler Adult Intelligence Scale - Fourth Edition, Australian and New Zealand Language Adapted Edition (WAIS-IV A&NZ). The WAIS-IV covers four cognitive domains: verbal comprehension; perceptual reasoning, working memory and processing speed. Scores in these four areas are then combined to give a Full-Scale IQ Percentile, which is one way of assessing an individual’s level of general intellectual functioning.