For thousands of years, humans have been observing each other and wondering what makes one person different from others.
Across those years, philosophers and scientists proposed many theories about the existence of personality types that could explain behavior.
According to this view, a “Type 1” person is fundamentally different from a “Type 2” or “Type 3” person on a wide range of interests, abilities, and behaviors.
Think “leaders” vs. “followers.”
As modern psychology developed in the 1900s, the focus shifted to personality traits—
enduring characteristics on which people could differ along a continuum.
Rather than classifying people as total “extraverts” or “introverts,” researchers realized that most people fall somewhere in the middle.
It was their relative position along that continuum that distinguished one person from another.