When people talk about intelligence tests, they often discuss "genius scores." What exactly constitutes a genius score on a measure of intelligence? In order to understand the score, it is important to first learn a little bit more about IQ testing in general.
Today's intelligence tests are based largely on the original test devised in the early 1900's by French psychologist Alfred Binet. In order to identify students in need of extra assistance in school, the French government asked Binet to devise a test that could be used to discover which students most needed academic help.
Based on his research, Binet developed the concept of mental age. Certain questions he posed were easily answered by children of certain age groups. Some children were able to answer questions that were typically answered by children of an older age - these children had a higher mental age than their actual chronological age. Binet's measure of intelligence was based on the average abilities of children of a particular age group.
Understanding IQ Scores
IQ scores generally follow what is known as the Bell Curve. In order to understand what the score on an IQ test means, there are a few key terms that you should know:
- Bell Curve: When IQ scores are plotted on a graph, they typically follow a bell-shaped curve. The peak of the "bell" occurs where the majority of the scores lie. The bell then slopes downward to each side - one side representing scores that are lower than the average, the other side representing scores that are above the average. An example of a bell curve can be seen in the image above.
- Mean: The average score. The average is calculated by adding all of the scores together, then dividing by the total number of scores.
- Standard Deviation: A measure of variability in a population. A low standard deviation means that most of the data points are very close to the same value. A high standard deviation indicates that the data points tend to be very spread out from the average. In IQ testing, the standard deviation is plus or minus 15.
A Breakdown of IQ Scores
Now that you understand these key terms, we can talk a bit more about how we interpret IQ scores. The average score on an IQ test is 100. Sixty-eight percent of IQ scores fall within one standard deviation of the mean. So that means that the majority of people have an IQ score between 85 and 115.
- 1 to 24 - Profound mental disability
- 25 to 39 - Severe mental disability
- 40 to 54 - Moderate mental disability
- 55 to 69 - Mild mental disability
- 70 to 84 - Borderline mental disability
- 85 to 114 - Average intelligence
- 115 to 129 - Above average; bright
- 130 to 144 - Moderately gifted
- 145 to 159 - Highly gifted
- 160 to 179 - Exceptionally gifted
- 180 and up - Profoundly gifted
Genius IQ Scores
So what is considered a genius IQ score? Generally, any score over 140 is counted as a high IQ. A score over 160 is considered by many to be a genius IQ score. Scores that are 200 and over are often referred to as "unmeasurable genius."
Learn more about IQ scores: