Maybe you’re wondering what a good IQ score is because you’re thinking about taking, or have recently taken, an IQ test. The short answer is that anything 15 points or so above 100 is probably a good score if you define good to be above average.
The reason for that is that 100 is the average IQ score for all ages, and a standard deviation is 15 away from the mean/average. Currently, IQ scores are based around a deviation system. There is some range of values that fit into a particular IQ category, meaning that while IQ is considered to be average at 100, values between 95-105 are often considered average. Similarly, values from 105-115 are often considered above average, and scores a deviation beyond this often considered genius. The exact values that fall within certain bins/categories will vary from IQ scale to IQ scale, but all current scales are based around an average of 100.
Systems Of IQ Rating
There are many different IQ classification systems for IQ tests. Some of the more notable IQ classification systems are: Wechsler Intelligence Scales, the Woodcock-Johnson Test of Cognitive Abilities, the Kaufman Tests, the Cognitive Assessment Test, and the Stanford-Binet Intelligence Scale. Not every test returns the result of the test as an “IQ score”, but most tests will give a standard score based around 100. Below, we’ll look at just a few of the classification systems currently used.
Weschler Classification System
130+: Highly superior
109-119: High Average
80-89: Low Average
69-: Extremely Low
Stanford-Binet Intelligence Scale
145-160: Highly advanced/gifted
130-144: Very advanced/gifted
110-119: High Average
80-89L Low Average
70 – 79: Borderline impaired
55 – 69: Mildly impaired
40 – 54: Moderately impaired
Kaufman Test Scales
130+: Upper Extreme
116-130: Above Average
70-84: Below Average
40-69: Lower Extreme
Remember that all test have some margin of error. The margin of error is reflected in the confidence interval, and test-proctors should inform the individual who took the test of the confidence interval for the test.
How Are IQ Tests Run?
IQ tests usually track an individual’s performance in a number of different categories, with the assumption that IQ isn’t a measure of an individual’s aptitude at any one form of thinking/problem solving but rather an amalgamation of these aptitudes that represents a general intelligence.
Some of the categories covered by IQ tests include logical reasoning, visual/spatial reasoning, analogies (both verbal and mathematical) patterns (mathematical and spatial), and classification. Questions may ask a test taker to:
- Determine which number comes next in a pattern
- Complete an analogy when given a few different options
- Find two words that are closest in meaning to one another
- Ask one to mentally unfold a six-sided die and then choose the image that correctly represents what it would look like unfolded.
The “G” Factor
There are many different forms of IQ tests. Some track things like a person’s verbal skills while others track traits like visual pattern recognition. It is difficult to say how an individual’s performance on one set of tasks is reflective of their intelligence overall, and for this reason, many psychologists have created models that attempt to find correlations between performance on one type of test and performance on another.
British psychologist Charles Spearman is arguably one of the most influential people in the study of intelligence, having done the first formal analyses on correlations between performance on different forms of intelligence tests. Spearman hypothesized that the various tests which could be used to track an individual’s intelligence all reflected a “General factor” or general intelligence – the “g-factor”. Spearman’s model predicted that if the g-factor was a real, measurable phenomenon, there should a “principle of indifference”. The principle of indifference suggests that the g-factor should reliably link together many different traits associated with intelligence without relying on the manifestation of any one trait in particular.
While the existence of a g-factor isn’t accepted by all psychologists, many tests and models of intelligence do look for (and find) an overlap between various types of intelligence.
Different Types Of Intelligence
There are different models of intelligence that IQ tests intend to track. As mentioned, most models of intelligence divide an individual’s intelligence into performance in different categories. One model is the Cattell-Horn-Carroll theory of intelligence, which divided intelligence into categories like: fluid intelligence, crystal intelligence, quantitative reasoning, visual processing and even reaction time.
Fluid intelligence refers to an individual’s ability to form associations between concepts, reason about ideas/concepts and implement new strategies to solve problems. Crystallized intelligence is in reference to a person’s body of knowledge, the depth of things a person knows and the accompanying ability to solve problems using already learned procedures. Quantitative reasoning is the ability to understand mathematical quantities, to see the relationships between quantities, to manipulate mathematical statements that use symbols. Visual processing is the ability to recognize and analyze visual patterns and think/reason in visual patterns. Reaction speed is how quickly an individual can react to a stimuli or task that demands their attention.
While most modern tests don’t explicitly measure all the attributes defined by the Cattell-Horn-Carroll theory, the theory was informative and useful in creating concepts/classifications of different forms of intelligence that could be used to gain more holistic understandings of a person’s general intellectual ability.
The Flynn Effect
The Flynn effect is a phenomenon where the mean IQ score tends to change as time goes on, trending upwards. In other words, there seems to be an increase in the general population’s intelligence, as defined by IQ scores. To compensate for the increase in intelligence, IQ tests must be recalibrated every so often, establishing tougher criteria for an average intelligence score every time the tests are rewritten. The effect was first described by intelligence researcher James Flynn.
There are various proposed explanations for the Flynn effect, such as the fact that on average, people have greater access to education now than a couple of generations ago. More people will attend school and they will stay in school for longer. It could also be that modes of thinking/reasoning and critical thinking tools used by scientists are being picked up by the average person thanks to increased education. It is also possible that those with intellectual disabilities are now receiving more support and better services, which bumps the average higher.