IQ, or intelligence quotient, is a score derived from a standardized test designed to measure intelligence. IQ tests formally emerged in the early 1900s with the introduction of the Binet-Simon test, which was later revised and became known as the Stanford-Binet.
IQ tests have proven to be very popular both within psychology and with the general public, but there remains a great deal of controversy about exactly what IQ tests measure and how accurate they are. While we often hear a lot of talk about high and low IQ scores, many people aren't quite sure what these designations really mean.
What exactly is considered a low IQ score?
An IQ score of 70 or below is considered a low score. Remember, on most standardized tests of intelligence, the average score is set at 100. Anything over 140 is considered high or genius-level. Sixty-eight percent of all scores fall within plus or minus 15 points of the mean (so between 85 and 115).
So what does it mean to have a score 70 or below? In the past, an IQ score below 70 was considered a benchmark for mental retardation, an intellectual disability characterized by significant cognitive impairments. Today, however, IQ scores alone are not used to diagnose intellectual disability. Instead, the criteria for a diagnosis includes an IQ below 70, evidence that these cognitive limitations existed prior to the age of 18, and limitations in two or more adaptive areas such as communication and self-help skills.
Approximately 2.2 percent of all people have an IQ score below 70.
Learn more about intelligence and the meaning of IQ scores:
- What Do IQ Scores Mean?
- What Is Considered a Genius IQ Score?
- What Is the Average IQ Score?
- The History of Intelligence Testing
Boeree, C. G. (2003). Intelligence and IQ. Retrieved from http://webspace.ship.edu/cgboer/intelligence.html