Gordon Willard Allport

Gordon Willard Allport (November 11, 1897 – October 9, 1967) was an American psychologist. Allport was one of the first psychologists to focus on the study of the personality, and is often referred to as one of the founding figures of personality psychology. He contributed to the formation of values scales and rejected both a psychoanalytic approach to personality, which he thought often was too deeply interpretive, and a behavioral approach, which he thought did not provide deep enough interpretations from their data. He emphasized the uniqueness of each individual, and the importance of the present context, as opposed to past history, for understanding the personality.

Main contributions：
①Allport's trait theory
Allport is known as a "trait" psychologist. One of his early projects was to go through the dictionary and locate every term that he thought could describe a person. From this, he developed a list of 4500 trait like words. He organized these into three levels of traits. This is similar to Goldberg's fundamental lexical hypothesis, or the hypothesis that over time, humans develop widely used, generic terms for individual differences in their daily interactions.

②Genotypes and phenotypes
Allport hypothesized the idea of internal and external forces that influence an individual's behavior. He called these forces Genotypes and Phenotypes. Genotypes are internal forces that relate to how a person retains information and uses it to interact with the external world. Phenotypes are external forces, these relate to the way an individual accepts his surroundings and how others influence their behavior. These forces generate the ways in which we behave and are the groundwork for the creation of individual traits.
The Problem with this hypothesis is that it cannot be proven as they are internal theories, influenced presumably by the outer environment.

Selected works by Gordon Willard Allport
Gordon Allport, The Scapegoats (1954)
Gordon Allport, Becoming (1955)
Gordon Allport, The Open System in Personality Theory (1960)

Reference
https://en.wikipedia.org/wiki/Gordon_Willard_Allport