Answer to Question 1
Today, the most widely accepted model of broad personality traits is the Big Five, also known as the Five Factor Model (FFM). This model, based on the results of factor analyses of everyday words used to describe personality characteristics, as the name implies, proposes that there are a total of five relatively independent factors that make up the entire personality. Paul Costa, Jr. and Robert McCrae are the two pioneers in the field most closely associated with the model. They developed a popular self-report instrument designed to measure the Big Five called the NEO-PI.
Answer to Question 2
Just as the trait of extraversion is linked to the BAS, the trait of neuroticism is linked to the BIS. High levels of neuroticism are associated with greater BIS sensitivity, and this may account for the predominant negative affect high neuroticism individuals experience. Thus, the higher BIS sensitivity of neurotic individuals explains their greater negative response to stressors or other stimuli they find threatening or punishing.
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