What classification is given to individuals who score below 20 on IQ tests?

• A. Borderline intellectual functioning
• B. Mild intellectual disability
• C. Moderate intellectual disability
• D. Profound intellectual disability

Answer: (D)

Understanding how IQ scores relate to levels of intellectual disability helps you see why a score below 20 is classified as profound intellectual disability. IQ tests compare a person’s cognitive abilities to the general population, with ranges that map to different levels of impairment. Mild intellectual disability generally falls around 50–69, moderate around 35–49, and severe around 20–34. When an IQ score is below 20, it indicates very significant cognitive limitations. Individuals in this category typically show substantial delays across multiple areas, such as communication, self-care, and mobility, and usually require intensive, ongoing support throughout life. They may also have additional physical or sensory disabilities that affect daily functioning. While IQ provides a snapshot of cognitive ability, the level of support needed is determined by adaptive functioning, but the cutoff below 20 is traditionally labeled profound intellectual disability.