<P> Historically, the concept of temperament (originally "temperamentums" in Latin means "mixtures") was a part of the theory of the four humors, with their corresponding four temperaments . </P> <P> This historical concept played an identifiable part in pre-modern psychology, and was explored by philosophers, psychologists, psychiatrists and psycho - physiologists such as Immanuel Kant, Hermann Lotze, Ivan Pavlov, Carl Jung, Gerardus Heymans among others . </P> <P> More recently, scientists seeking evidence of a biological basis of personality have further examined the relationship between temperament and neurotransmitter systems and character (defined in this context as developmental aspects of personality). However, biological correlations have proven hard to confirm . </P> <P> Temperament is determined through specific behavioral profiles, usually focusing on those that are both easily measurable and testable early in childhood . Commonly tested factors include traits related to energetic capacities (named as "Activity", "Endurance", "Extraversion"), traits related to emotionality (such as irritability, frequency of smiling, and an approach or avoidance of unfamiliar events . There is generally a low correlation between descriptions by teachers and behavioral observations by scientists of features used in determining temperament . Temperament is hypothesized to be associated with biological factors, but these have proven to be complex and diverse . </P>

Which of the following is one of thomas and chess’s temperament styles