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What are four biological trait explanations that one can use to discuss the role that biological conditions play in controlling human behavior?

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Researchers have developed many different theories to try to explain how biological traits play a role in controlling human behavior, and these theories include William H. Sheldon's body type theory; Gordon Allport's personality trait categories; Hans and Sybil Eysenck's ideas about temperament; and the Five Factor Model. Let's look briefly at each of these.

Sheldon proposed that a person's body type actually influences his or her personality. He identified three body types—ectomorphs, endomorphs, and mesomorphs—and tried to match them with various personality traits. Ectomorphs, o very thin people, are supposed to be quiet, anxious, thoughtful, and introverted. Endomorphs, who are heavier, are sociable and relaxed. Mesomorphs, who fall somewhere in the middle, are assertive and adventurous. This theory really doesn't work very well, and we can all think of exceptions to it.

Allport identified three categories of personality traits: cardinal (dominating), central (prominent), and secondary (present in some situations). These traits, he claimed, drive people's behavior and help us understand why we act as we do.

Hans and Sybil Eysenck focused on extroverted and introverted temperaments as well as neurotic and stable emotions, and they tried to identify the biological bases for all of these as well as how they work together in individuals. The Eysencks used the classical Greek terminology of sanguine, phlegmatic, choleric, and melancholic for their classifications.

Finally, the Five Factor Model looks at the openness, conscientiousness, extroversion, agreeableness, and neuroticism of individuals across a spectrum, noticing how these traits influence behavior and how they change over time.

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