Step 1: Concept Definition:
The trait approach focuses on identifying and quantifying stable individual characteristics (traits). Conversely, the type approach categorizes individuals into distinct groups (types). The objective is to identify the theorist who is not part of the trait approach.
Step 2: Theorist Analysis:
Review of listed theorists:
Costa and McCrae: Prominent modern trait theorists, creators of the "Big Five" personality model (Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism).
Allport: Gordon Allport, a foundational figure in trait theory, who differentiated between cardinal, central, and secondary traits.
Sheldon: William Sheldon's constitutional theory is a type theory. He classified individuals into three somatotypes (endomorph, mesomorph, ectomorph) and linked these to personality characteristics.
Cattell: Raymond Cattell, a significant trait theorist, utilized factor analysis to identify 16 primary personality traits (16PF).
Step 3: Conclusion:
Costa and McCrae, Allport, and Cattell are all associated with the trait approach. Sheldon belongs to the type approach. Therefore, Sheldon is the correct answer.