The Big Five (also called Five Factor) trait model of personality is the most widely accepted personality theory in the scientific community. Although it is not as well understood among laypeople as systems like Myers-Briggs personality typing, it is generally believed to be the most scientifically sound way of conceptualizing the differences between people.
The Big Five is so named because the model proposes that human personality can be measured along five major dimensions, each of which is distinct and independent from the others. The Big Five model is also sometimes called OCEAN or CANOE, both acronyms of the five personality traits.
In the Big Five model, people are understood to have varying levels of key personality factors which drive our thoughts and behavior. Although personality traits cannot specifically predict behavior, differences in the Big Five factors help us to understand why people may react differently, behave differently, and see things differently from others in the same situation.
The Big Five is a trait model of personality, rather than a type model. Most popular ways of describing personality talk about personality types, such as Type A or Type B personalities, or Myers & Briggs' INFPs and ESTJs. Although type models are easy to understand, they are not scientifically sound, as people don't neatly sort into categories. The Big Five describes people in terms of traits on a spectrum, and as such, is a much more valid and evidence-based means of understanding personality.
In the Big Five model, the five dimensions of personality are:
Not to be confused with one's tendency to be open and disclose their thoughts and feelings, Openness in the context of the Big Five refers more specifically to Openness to Experience, or openness to considering new ideas. This trait has also been called "Intellect" by some researchers, but this terminology has been largely abandoned because it implies that people high in Openness are more intelligent, which is not necessarily true.
Openness describes a person's tendency to think abstractly. Those who are high in Openness tend to be creative, adventurous, and intellectual. They enjoy playing with ideas and discovering novel experiences. Those who are low in Openness tend to be practical, traditional, and focused on the concrete. They tend to avoid the unknown and follow traditional ways.
In the brain, Openness seems to be related to the degree to which certain brain regions are interconnected. Those high in Openness seem to have more connection between disparate brain regions, which may explain why they are more likely to see connections where others do not.
Conscientiousness describes a person's level of goal orientation and persistence. Those who are high in Conscientiousness are organized and determined, and are able to forego immediate gratification for the sake of long-term achievement. Those who are low in this trait are impulsive and easily sidetracked.
In the brain, Conscientiousness is associated with frontal lobe activity. The frontal lobe can be thought of as the "executive brain," moderating and regulating the more animal and instinctual impulses from other areas of the brain. For example, while we might instinctually want to eat a piece of cake that's in front of us, the frontal lobe steps in and says "no, that's not healthy, and it doesn't fit in with our diet goals." People who are high in Conscientiousness are more likely to use this brain region to control their impulses and keep themselves on track.
Extraversion describes a person’s inclination to seek stimulation from the outside world, especially in the form of attention from other people. Extraverts engage actively with others to earn friendship, admiration, power, status, excitement, and romance. Introverts, on the other hand, conserve their energy, and do not work as hard to earn these social rewards.
In the brain, Extraversion seems to be related to dopamine activity. Dopamine can be thought of as the "reward" neurotransmitter, and is the main chemical associated with our instinct to pursue a goal. The classic example is a rat in a maze, whose brain pumps out dopamine as he frantically seeks the cheese. Extraverts tend to have more dopamine activity, indicating that they are more responsive to the potential for a reward. Introverts have less dopamine activity, and so are less likely to put themselves out to chase down rewards.
Agreeableness describes the extent to which a person prioritizes the needs of others over their own needs. People who are high in Agreeableness experience a great deal of empathy and tend to get pleasure out of serving and taking care of others. People who are low in Agreeableness tend to experience less empathy and put their own concerns ahead of others.
Neuroticism describes a person's tendency to respond to stressors with negative emotions, including fear, sadness, anxiety, guilt, and shame.
This trait can be thought of as an alarm system. People experience negative emotions as a sign that something is wrong in the world. Fear is a response to danger, guilt a response to having done something wrong. However, not everyone has the same reaction to a given situation. High Neuroticism scorers are more likely to react to a situation with strong negative emotions. Low Neuroticism scorers are more likely to brush off their misfortune and move on.
In the brain, Neuroticism appears to relate to the interconnection of several regions, including regions involved in processing negative stimuli (such as angry faces or aggressive dogs) and dealing with negative emotions. One study found an association between high Neuroticism and altered serotonin processing in the brain.
How the Big Five Traits Describe Personality
Individuals are typically described in terms of having high, average, or low levels of the five personality factors. Each factor is independent from the others, so someone might be high in Extraversion and low in Agreeableness. To gain a full picture of an individual using the Big Five model, it's necessary to know how they measure up on each of the five dimensions. You can measure your own levels of the Big Five personality traits with a Big Five personality test.
History of the Big Five
The Big Five model has its roots in a theory called the lexical hypothesis—the idea that we can create a sort of taxonomy of individual differences by examining the language we use to describe each other. Early researchers took an inventory of words that describe personality traits, such as "friendly," "helpful," "aggressive," and "creative." They then attempted to organize these words into related clusters. For instance, a person who's described as friendly is also likely to be described as gregarious, talkative, and outgoing. Researchers consistently found that trait-related adjectives tended to cluster into five groups, corresponding to the five traits in the Big Five.
Today, the Big Five model is the basis of most modern personality research, and as such has been used to illuminate everything from how much of our personality is inherited to which personality factors correlate with income.