Question
What IQ is considered intellectual disability?
Short answer
No IQ score alone defines intellectual disability. The AAIDD definition requires significant limits in both intellectual functioning and adaptive behavior, starting before age 22. It treats an IQ score of around 70, or as high as 75, as indicating a significant limitation in intellectual functioning, once measurement error is considered.
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The definition has three parts
The American Association on Intellectual and Developmental Disabilities (AAIDD) defines intellectual disability as a condition with significant limitations in both intellectual functioning and adaptive behavior, originating before the age of 22 (AAIDD). All three parts matter:
- Intellectual functioning. Usually measured with a standardized IQ test. A score of around 70, or as high as 75, indicates a significant limitation (AAIDD).
- Adaptive behavior. The conceptual, social and practical skills people use in everyday life, assessed with separate standardized measures (AAIDD).
- Age of onset. The condition begins during the developmental period, before age 22.
Try one · Logical Reasoning
Which tile completes the second pair?
Tap the option you think is right, or show the answer.
Show the answer
The missing panel shows a small solid diamond, with small solid shapes: a square at the bottom (option 5).
How to solve it
- Compare the first two panels and name exactly what changed.
- The main shape and the small shapes swap forms: the main shape takes the form of the small ones, and the small ones take the form of the main shape.
- Nothing else changes.
- Apply the same change to the third panel: a small solid square, with small solid shapes: a diamond at the bottom.
- So the missing panel shows a small solid diamond, with small solid shapes: a square at the bottom.
That was 1 puzzle. The full test has 25.
Where 70 sits on the curve
70 is two standard deviations below the mean of 100. About 95% of people score between 70 and 130 (the 68-95-99.7 rule), so roughly 2.3% score below 70. On the WAIS-IV, 70 to 79 is labeled Borderline and 69 and below Extremely Low (Wikipedia: IQ classification). Those labels describe test scores, not diagnoses.
Why a range instead of a line
No test measures perfectly. Clinical manuals report a confidence interval, often around plus or minus 5 points at 95% (Wechsler, 2008). A measured 73 is consistent with a true level a few points either side. That is why the definition speaks of a score around 70 rather than a hard cutoff, and why everyday functioning carries equal weight.
Getting a proper assessment
Diagnosis is a job for a qualified professional using supervised tests. An online test is not a substitute and cannot be used for disability assessment. For what the scores near this range mean, see what IQ is considered low, what a borderline IQ means and IQ 70.
Sources
- Defining criteria for intellectual disability. American Association on Intellectual and Developmental Disabilities. www.aaidd.org/intellectual-disability/definition
- IQ classification. Wikipedia. en.wikipedia.org/wiki/IQ_classification
- 68-95-99.7 rule. Wikipedia. en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule
- Wechsler, D. (2008). WAIS-IV Technical and Interpretive Manual. Pearson.