-impairments of general mental abilities that impact adaptive functioning in 3 domains or areas
1. conceptual domain: skills in language, reading, writing, math, reasoning, knowledge and memory
2. social domain: empathy, social judgement, interpersonal communication skills, the ability to make and retain friendships, and similar capacities
3. practical domain: centers on self management in areas such as personal care, job responsibilities, money management, recreation and organizing school and work tasks