Biological Theory of Personality

Definition of the Biological Theories of Personality

The argument of nature vs. nurture seems as old as time. Do our personalities come from genetic coding, or are they the result of the influence of the people around us? While many can argue that it’s a combination of both nature and nurture, others focus more on the nature side of personality. Biological theories of personality are a group of theories that argue for the nature (or biological) side of this ongoing debate.

When looking through the biological lens when it comes to personality, just remember that we are trying to view the person as they are. Biological theories of personality do not look at external factors (e.g., the influence of others around them), but rather at internal factors (e.g., genetics) to explain why our personalities are the way they are.

These theories try to observe how someone became who they are through genetics, neuroscience, DNA, and other internal factors.

Biological Theories of Personality Development

There are several different ways that our biology can impact our personality throughout our lives. It's about much more than just our genetics! Hormones, traumatic events, neurotransmitters, and other factors can impact and alter our personalities. Some of the biological bases of personality include:

• Genetic Factors/DNA

  Anxiety disorders or tendencies towards anxiety can be passed down in a family. There is no specific gene for anxiety. Several different genes seem to play a role in anxious dispositions.

• Brain Structures

  An ongoing study that is being done on Cattell’s "Big 5" personality traits model shows that people who measure higher in conscientiousness tend to have larger lateral prefrontal cortexes than those who are low in conscientiousness. The lateral prefrontal cortex is a brain structure that plays a role in our organization and behavior.

• Hormone Secretions

  The hormone testosterone (present in males and females but more so in males) is vital for its impact on our sociability, aggression, and sexuality.

Biology can shape our personalities as we age and progress through the different phases of childhood, adolescence, and adulthood. Biological theories of personality development want to look at the consistent and inconsistent aspects of our personalities over time as they relate to biological causes or factors.

It would seem that our personalities tend to remain consistent, despite environmental influences. This is an argument in favor of nature over nurture (or biological causes over environmental ones). If a baby is quiet and prefers to play by itself, they will develop into an adult that also prefers quiet and alone time.

Biological Theories of Personality in Psychology

There are many biological theories for personality, but for this article, we will look at the following psychologists and their theories: Jeffrey Gray’s Reinforcement Sensitivity Theory, and Hans Eysenck's Three-Factor Model of Personality (PEN model).

Reinforcement Sensitivity Theory

Jeffrey Gray’s Reinforcement Sensitivity Theory is based on the notion that we use three types of biologically-driven responses when faced with stress or fear. It posits that everyone has a specific response method when faced with certain stimuli. These individual reactions can underlie personality traits for anxiety and impulsivity.

The three responses that people use when faced with stress or fear are called the fight, flight, or freeze response. This process explains that the person will either fight (face the stimuli head-on), fly (run away from the stimuli), or freeze (not react to stimuli) in stressful or fear-inducing situations. How one instinctively reacts can correspond with personality traits linked to anxiety, overthinking, impulsivity, and worrying.

Jeffrey Gray also introduced two behavioral systems that coincided with neurobiological processes.

Gray's Behavioral Inhibition System

Gray theorized that our responses to situations we associate with negativity can be predicted, because our brain recalls previous reactions to the same event or environment. The behavioral inhibition system is a neurobiological system that can predict our response to specific stimuli, because of earlier experiences that we viewed as negative.

This behavioral system is associated with personality traits that involve carefulness, trust, anxiety, and emotionality.

Gray's Behavioral Activation System

In contrast, Gray's behavioral activation system suggests that our brain/body is predisposed to pursuing and achieving goals due to our mind's positive association. The behavioral activation system is a neurobiological system that promotes motivation and encourages the pursuit of goals based on experiences that we view as positive.

This behavioral system is associated with personality traits that involve self-consciousness, self-discipline, and dutifulness.

Hans Eysenck's Biological Theory of Personality

Hans Eysenck was a German psychologist known for his PEN model. It is one of the major biological theories of personality. The PEN model is based on three personality traits that Eysenck believed correlated with the activation of our limbic system and reticular formation. Both are structures of the brain and they each play a key role in brain and body function. The limbic system focuses on emotion, behavior, and memory, while the reticular formation focuses on arousal and consciousness.

The three personality traits for the PEN model are Psychoticism, Extraversion, and Neuroticism. Eysenck referred to these three traits as super-traits.

Psychoticism and Normality

The P in PEN stands for Psychoticism. If someone scores high in psychoticism, their personality would reflect someone more likely to ignore social norms, as they are not motivated by incentives. People in this category are also more likely to disregard authority and rules set by others. However, Eysenck also noted that people in this category are very creative and like to think outside the box.

If someone scores low in psychoticism, their personality would reflect someone who is sensitive, empathetic, and more likely to follow the rules set by others. People who score low in psychoticism are also more likely to avoid conflict as they prefer peaceful environments.

Personality traits linked to Psychoticism (High):

• Aggressive

• Cold

• Impersonal

Extraversion and Introversion

The E in PEN stands for Extraversion. If someone scores high in extroversion, they have a personality that is more sociable and outgoing. Extroverts enjoy environments where they can be social and have attention. If someone scores low in this category, they have a quieter personality that prefers an environment with smaller crowds and activities that they can do alone. (This does not mean they are lonely or reclusive, however.)

Personality traits linked to Extroversion (High)

• Carefree

• Sociable

• Lively

Neuroticism and Stability

In Eysenck’s PEN model, N stands for Neuroticism. If someone scores high in neuroticism, they have a personality that is oriented towards the self and are more likely to experience stress and anxiety. A low score would indicate they have a calm personality and are more laid back. They will also be better at handling stress and anxiety.

Personality traits linked to Neuroticism (High)

• Tense

• Anxious

• Moody