How do individuals in the intellectually gifted and intellectually disabled groups differ from the normal population?

They deviate considerably in their cognitive, emotional, and motivational characteristics.

All persons do not have the same intellectual capacity; some are exceptionally bright and some are below average. One practical use of intelligence test is to identify persons at the extremes of intellectual functioning. If you refer to Table below, you will notice that about 2 per cent of the population have IQ above 130, and a similar percentage have IQ below 70. The persons in the first group are called intellectually gifted; those in the second group are termed intellectually disabled. These two groups deviate considerably from the normal population in respect of their cognitive, emotional, and motivational characteristics.

Classification of People on the Basis of IQ

 IQ Range                   Descriptive Label                    Per cent in the Population

Above 130                    Very superior                                     2.2

120 – 130                       Superior                                         6.7

110 – 119                      High average                                   16.1

90 – 109                        Average                                         50.0

80 – 89                            Low average                                16.1

70 – 79                          Borderline                                      6.7

Below 70                        Intellectually disabled                       2.2