Biological Perspectives in Psychology PS338

Biological/Evolutionary Perspectives PS338

• Biological perspectives examine the brain and its role in personality and behavior.
• Key aspects of the brain examinable with technology include brain anatomy, neurochemistry (effects of neurotransmitters and hormones on brain processes).
• These aspects are directly relevant to personality and behavior.

Research Methods for Studying the Brain

• Brain damage: Methods involve studying damage cases such as Phineas Gage, or lesions.
• Brain stimulation: Mostly studies on animals, but also occasionally on conscious humans. Methods include transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS).
• Brain activity and imaging: Methods used to directly observe brain functioning. Techniques like electroencephalography (EEG), magnetoencephalography (MEG), computed tomography (CT) scans, positron emission tomography (PET), and functional magnetic resistance imaging (fMRI) are employed.
• Difficulties with imaging techniques: All parts of the brain are active to some degree. Blood oxygenation level dependent (BOLD) imaging and perfusion imaging signals can be misleading about which part of the brain is active at any given time. Most research concentrates on small areas of the brain, making it difficult to see the neural context effect. Studying brain activity and imaging is difficult and expensive.

Personality and the Brain

• The illustration shows various parts of the brain, including the corpus callosum, cingulate cortex, frontal cortex, basal ganglia, hypothalamus, amygdala, thalamus, hippocampus, brain stem, spinal cord, afferent nerves, and efferent nerves.

The Amygdala

• Links perceptions and thoughts with emotional meaning.
• Plays a role in negative and positive emotions.
• Assesses whether a stimulus is threatening or rewarding.
• Relevant traits include anxiety, fearfulness, sociability, and sexuality.
• Relevant for motivation (e.g., Whitman murders, 1966).

The Frontal Lobes and the Neocortex

• Involved in higher cognitive functions.
• Related to emotional processing: pleasant emotions (left), unpleasant emotions (right), approach (left), and withdrawal (right).
• Includes the inhibition of reactions to unpleasant stimuli.
• Related to emotional stability (left), and neuroticism (right); propensity to get angry (left).
• Also relevant to social and emotional understanding, self-control, and regulation of impulses and feelings. Case studies on Phineas Gage (1848) and Elliott are mentioned.
• Associated with the Somatic marker hypothesis.

The Anterior Cingulate

• Important for experiencing normal emotions.
• Influences the control of emotional responses and behavior impulses.
• Possibly linked to positive and negative affective differences between extraversion and neuroticism (e.g. Charles Whitman).

Brain Systems

• The brain is highly interconnected.
• The persistence system connects frontal cortex and striatum.
• The C-system connects lateral PFC, hippocampus, medial temporal lobe, and posterior parietal cortex.
• The X-system connects vmPFC, amygdala, and lateral temporal cortex.
• There is a neural context effect in the functioning of brains.

The Biochemistry of Personality

• Galen proposed that personality is influenced by the balance of humors (blood, black bile, yellow bile, and phlegm).

• The chemistry of the brain depends on neurotransmitters like the chemicals: Endorphins.

• Neurons communicate using neurotransmitters.

• Another related chemical: Hormones that stimulate neural activity.

• Associated brain systems: Central and peripheral nervous system.

Eysenck's Biological Basis of Personality

• Hans Eysenck linked personality to biological functions.
• Proposed the PEN theory.
• Introverts are quiet, retiring, and socially reserved; extraverts are outgoing, uninhibited, and immersed in social activity.
• Eysenck argued that differences between introverts and extraverts are due to differences in the activation of the cerebral cortex.
• The ARAS (Ascending Reticular Activating System) is involved in these cortical arousal differences.
• Low ARAS resting activity is associated with extraversion; High ARAS resting activity with introversion.
• Introverts are more highly aroused than extraverts.
• Extraverts easily get bored (under-aroused) and seek out more stimulation. Conversely introverts are constantly over-aroused and so prefer peace and quiet.
• Introverts need less stimulating drugs for non-alertness; extraverts need more stimulating drugs (e.g., caffeine, coffee, chocolate).
• Introverts have more saliva (react more strongly) with lemon juice.

Biological Basis of Personality - Gray

• Proposed BIS and BAS theories. BIS (Behavioral Inhibition System) regulates actions based on punishment. BAS (Behavioral Activation System) regulates actions based on rewards.
• Strong BIS and weak BAS is associated with Negative Emotionality
• Strong BAS and weak BIS is associated with Positive Emotionality.

Biological Basis of Personality - Genetics

• Behavioral genetics addresses how personality traits are inherited.
• Twin studies, examining both MZ (identical) and DZ (fraternal) twins, compare similarities in personality traits amongst related and non-related people to understand genetic influence.
• MZ twins share nearly 100% of their genes; DZ twins approximately 50%.
• Shared environments vs unique (non-shared) environments influence behavior.
• Eysenck and Prell observed the heritability of traits through twin studies (1951).
• The Minnesota Twin Family Study (started in 1979) followed identical and fraternal twins separated at birth.
• Personality variations like the "Big Five" personality dimensions were also shown to have heritability in research in 1996.
• Different genes were found to have different degrees of influence on the Big Five traits like neuroticism (41%), extraversion (53%), openness (61%), agreeableness (41%), and conscientiousness (44%).

Genes and Environment

• Genes are important for brain development. The precise manifestation, however, is affected by random developmental processes.
• The nature vs nurture debate.

Jean Baptiste Lamarck

• A French Naturalist
• Proposed the theory of inheritance of acquired characteristics. The idea is that a characteristic developed during the lifetime of a parent can be directly inherited by the children.

Charles Darwin and Natural Selection

• Variation in a species is due to genetic difference.
• Useful traits (for survival and reproduction) are passed down to offspring.
• Natural selection drives variation towards more adaptive traits.
• Mutations lead to variation in genes.
• Domestication is illustrative of animal selection; it is not possible to have selection without variation.

Why does Personality Exist?

• Personality traits contribute to adaptive fitness through behavioral variation and motivational systems.

Environmental Contexts

• Environmental variation impacts the expression of personality traits; genetic variation also exists alongside a wide range of environmental circumstances, for millions of years.
• Effects of Culture, geography, and language on personality expression are difficult to control; particular environmental settings may favor certain personality profiles over others.

Evolutionary Psychology Perspective

• Assumes a genetic basis for behavior, but also encompasses environmental influences.
• It has focused on survival, mating strategies, kinship, and altruism.
• Addresses trade-offs, cost-benefit analyses of personality traits.
• Evolutionary psychology has explored frequency-dependent selection, where the effectiveness of a trait depends on its frequency in a population.
• The concept of the environment of evolutionary adaptiveness (EEA) describes the environments faced by our ancestors.

Sociobiology - Altruism

• Sociobiology examines the evolutionary basis of altruistic behavior.
• Altruistic behavior may have a genetic foundation, benefiting those sharing genes (kin selection).

Beware: Biological Reductionism

• Claims concerning sex differences in personality ( e.g. mathematical ability, verbal skills, temperament, emotionality, aggression, promiscuity, leadership, moral reasoning, self-esteem, conscientiousness are frequently scrutinized)
• Large-scale personality studies show some sex differences in neuroticism and agreeableness . Some researchers argue that the most significant discrepancies are found in cultural settings in particular places.

Problems with Evolutionary Psychology Approaches

• Post-hoc reasoning.
• Complexity of personality: complete assessment from genes is not a straightforward problem.
• Highly speculative nature.

Explore the intricate connections between biological processes and personality in this quiz focusing on Biological Perspectives in Psychology PS338. Dive into brain anatomy, neurochemistry, and various research methods used to study brain function, including imaging techniques and stimulation methods. Test your comprehension of how these elements influence behavior.