A psychologist who classifies an individual's personality according to the person's manifestations of traits such as neuroticism, openness, and extraversion probably believes in which model of personality?

The answer is the five factor model, also known as the Big Five.

Explanation:

This model was suggested as an alternative to other models, such as Allport's, which included over 4,000 traits; or Cattell's, including sixteen. The Big Five model encompasses five different dimensions which most people possess to different degrees.

The traits considered are: openness, conscientiousness, extraversion, agreeableness and neuroticism. These factors are believed to be universal, or at least the most accurate for describing worldwide cultures.