Temperament refers to the individual differences in behavioral tendencies that are present early in life and are relatively stable across different situations and over time. It is believed to be biologically based and influenced by genetic factors. Researchers in the field of temperament study how these individual differences manifest in areas such as emotional reactivity, activity level, and sociability. They also investigate how temperament traits can interact with environmental factors to affect development and behavior. Overall, the study of temperament provides valuable insights into understanding and predicting an individual's personality and behavior.