Alfred Binet introduced the concept of Mental Age. It is defined as the age at which the person successfully performs on all items of the test prepared for that age level. Mental Age need not correspond to Chronological Age. If Mental Age (MA) is the same as Chronological Age (CA), the person has average intelligence. For e.g., Sumit aged 10 years has successfully performed all items on the test for age 12. Hence, his Mental Age will be 12 years, i.e., he has above average intelligence.