Solved IGNOU Assignment >> MPC003 >> Q4

4. Describe neuro-psychological basis of trait and types.

Human behaviors and experiences are generated by biological processes, primarily within the brain. The regularities in these behaviors and experiences that constitute personality are, therefore, associated with regularities in the biological functions of the brain. The neuro-psychological base of various personality theories is discussed below:



Eysenck's Three Factor Model of Personality

Eysenck (1967; Eysenck & Eysenck, 1985) relied on the functions of the brain’s ascending reticular activating system, associating Extraversion with the reticulo-cortical circuit and Neuroticism with the reticulo-limbic circuit. He hypothesized:
(a) Extraverts have lower baseline levels of cortical arousal than introverts and and they may have higher preferred or optimal levels of arousal.
(b) Neurotics are more easily aroused by emotion-inducing stimuli than are emotionally stable people.
(c) Psychoticism was negatively associated with serotonergic function (Eysenck, 1992) and positively associated with dopaminergic function (Eysenck, 1997).

Gray's Reinforcement Sensitivity Theory

Jeffrey Gray developed a “conceptual nervous system”(CNS) describing functional systems that could be mapped onto brain systems. The main components of CNS are:
1. Behavioral Approach System (BAS): responds to cues for reward and is linked to the dopaminergic system,
2. Fight-Flight-Freezing System (FFFS) is linked to the amygdala, hypothalamus, and periaqueductal gray.
3. Behavioral Inhibition System (BIS): responds to two distinct classes of threatening stimuli (Gray & McNaughton, 2000; Pickering & Gray, 1999) and is linked to the septo-hippocampal system but also to the amygdala.

Cloninger Model of Personality

It is based on the idea that different responses to punishing, rewarding, and novel stimuli is caused by an interaction of the three dimensions:
1. Novelty Seeking (NS) – degree of impulsiveness. Correlated with low dopamine activity and increased grey matter volume in regions of the cingulate cortex.
2. Harm Avoidance (HA) - degree of anxiety. Correlated with high serotonin activity and decreased grey matter volume in the orbitofrontal, occipital, and parietal cortex.
3. Reward Dependence (RD) – Degree of approval seeking behaviour. Correlated with low norepinephrine activity and decreased grey matter volume in the caudate nucleus.

Five Factor Model of Personality

Four of the traits are found to be correlated with volumes of specific brain areas as discussed below:
1. Openness: acquisition of broad verbal intellectual skills and knowledge not localized to a specific brain region or neurotransmitter system.
2. Conscientiousness: increased volume in lateral prefrontal cortex, region involved in planning and the voluntary control of behavior.
3. Extraversion: increased volume of medial orbitofrontal cortex, region involved in processing reward information.
4. Agreeableness: increased volume in regions that process information about the intentions and mental states of other individuals.
5. Neuroticism: increased volume of brain regions associated with threat, punishment, and negative emotions.

* * *

The behaviors and experiences of humans are generated by biological processes that happen in the brain and related parts of the body. Psychologists seek to identify the various areas and physiological reactions that drive these. An attempt has accordingly been made by various personality theorists and researchers to identify the neuropsychological bases of the various traits and types of personality.

Sources:
http://en.wikipedia.org/wiki/Biological_basis_of_personality
http://www.tandfonline.com/doi/abs/10.1080/13803391003689770#.VLtEK9KUeE4
http://en.wikipedia.org/wiki/Gray%27s_biopsychological_theory_of_personality
Personality Neuroscience: Explaining Individual Differences in Affect, Behavior, and Cognition, Colin G. DeYoung Jeremy R. Gray (DeYoung_Gray_personality_neuroscience) (Click for article)

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