Intellectual functioning refers to the "general mental ability that includes reasoning, planning, problem solving, abstract thinking, comprehending complex ideas, learning quickly and learning from experience". Significantly limited or impaired intellectual functioning characterizes intellectual disabilities.
Ageing has been shown to cause a decline in intellectual functioning.
- American Association on Intellectual and Developmental Disabilities (AAIDD) Manual on Definition, Classification and Support Systems in Mental Retardation (Schalock et al., 2010)
- Wehmeyer, Michael L.; Thompson, James R. (September 2016). "Intellectual disability and support needs". American Association on Intellectual and Developmental Disabilities.
- Schaie, K. Warner; Willis, Sherry L. (1986). "Can Decline in Adult Intellectual Functioning be Reversed?" (PDF). Developmental Psychology. 22: 223–232. doi:10.1037/0012-1622.214.171.124.