The indicates that there are 16 distinctive personality types.

The answer is: Myers–Briggs Type Indicator
The Myers–Briggs Type Indicator was created by Carl Jung in 1929. It divide the human psychology into 16 distinctive personality types based on their level of Extroversion, Introversion, Perceptiveness, Judgement, Intuitiveness, Logical Thinking, Sensitivity to feelings, and the ability to stay objective