Biological Basis of Personality

• Human behavior, thoughts, emotions, and experiences directly link to physical and biological processes, forming the biological basis of personality.

Cross-Species Similarities

• Humans and other animals show striking anatomical and chemical resemblances.
• Thyroid medication for dogs is identical to that for humans.
• Anti-depressants like Prozac work on both humans and monkeys.
• Anti-anxiety medication for cats also works for humans.

Intersectionality and Physiological Mechanisms

• Intersectionality studies the connections between biology, personality, and physiology.
• Physiological mechanisms are biological systems like the immune and autonomic nervous systems interacting with behavior and the environment.

Brain Significance

• The brain is crucial for the mind and behavior, dating back millennia.
• Brain as the origin of pleasures, joys, sorrows, pains, thoughts, and perceptions, according to Hippocrates.
• The brain and its nerves are the physical basis of personality.

Brain Composition

• The average brain contains approximately 86-100 billion neurons.
• The brain consumes about 20% of the body's energy and 40% of glucose but makes up only 2% of the body's weight.

Key Brain Structures and Functions

• The hypothalamus secretes hormones affecting the entire body and sits below the thalamus, important for arousal.
• The hippocampus is involved in memory processing, especially emotional memories, and plays a role in PTSD.
• The neocortex, more evolved in humans, associates with consciousness, metacognition, personality, and emotional regulation.

Neuronal Communication

• Neurons act as gates and wires in the brain, gathering and transmitting information through electrochemical signaling.

Neuron Structure

• Soma: The cell body of the neuron.
• Dendrites: Branch-like extensions that receive information from other neurons.
• Axon: Sends information out to other neurons.
• Synapse: The gap between the axon of one neuron and the dendrite of another, where communication occurs.
• Neurons send information chemically, producing electricity, which is electrochemical communication
• Neuronal Firing is The process by which a chemical message is sent through an electrical signal.

Neurotransmitters

• Neurotransmitters are chemicals in the brain that enable neuronal communication.
• Serotonin, an example, is also found in the digestive tract as a hormone.
• Influence heart rate, breathing, temperature regulation, and digestion by relaying signals between nerve cells
• Impact sleep, mood, concentration, and weight.
• 80-85% of Americans have suboptimal neurotransmitter levels
• Factors for Neurotransmitter Depletion include stress, poor diet, neurotoxins, genetic predisposition, alcohol, caffeine, and drugs.
• Neurotransmitters significantly affect how people think, feel, and function in both healthy and unhealthy states.

Physiological Methodologies

• Tools and techniques used to investigate the relationship between physiology and personality.

Key Measures

• Include Electrodermal Activity (EDA) / Skin Conductance, Cardiovascular Activity, and Brain Activity.

Electrodermal Activity (EDA)

• Measures changes in activity in the autonomic nervous system (activated by stress, anxiety, or anger) through sensors on the skin.
• Sweat glands on palms and soles facilitate electricity conduction.
• People with anxiety may have higher autonomic nervous system activation.
• Benefits are being non-invasive and providing a general idea of stress response.
• Disadvantages are constrained movement and inaccurate readings without baseline measurements.
• Lie detector tests are based on electrodermal activity but aren't very reliable.

Cardiovascular Activity

• Primarily blood pressure, measures physiological response.
• Heart rate is greater than normal during cognitive work.
• Measured by heart rate before and doing a task like subtracting backwards from 100 by 7.
• Type A Personality: Competitive, time-pressured, and easily frustrated, shows higher cardiac reactivity.
• Type B Personality: Calm, patient, and organized.
• Type A individuals show significantly elevated cardiac reactivity, especially when competing for a prize.
• Type A personalities are more prone to heart problems due to chronic cardiac activity.
• Stress Management: Important for individuals with Type A personalities to manage stress and reduce cardiovascular disease risk.

Measuring Brain Activity

• Electroencephalogram (EEG) is the oldest technique for measuring brain activity.
• The brain produces electricity spontaneously, even during sleep.
• Lack of electricity indicates brain death.

Electroencephalography (EEG)

• EEG measures electrical activity in the brain using electrodes on the scalp.
• Procedure: Electrodes placed on the scalp detect electrical signals.
• Stimuli: Participants are given stimuli such as passages to read or pictures to look at.
• Event-Related Potential (ERP) Technique: Readings are taken before and after the stimulus to assess brain responses.
• Manipulation: Researchers manipulate variables to assess brain responses.
• Lacks specificity to detailed brain activity hence a limitation.
• Like hearing noise outside a stadium because you know something is happening but not the specifics, which is an analogy
• Applications: Commonly used in sleep studies to detect specific brainwave patterns associated with different sleep stages.
• Helps in identifying sleep disorders like insomnia.

Brain Imaging Techniques

• PET and fMRI map the structure and function of the brain.

PET Scan (Positron Emission Tomography)

• Tracer Substance: A short-lived tracer substance is used.
• Metabolic Activity: The tracer is used by active brain cells, and brain activity increases the tracer's metabolism rate.
• Scanner Detection: Detects where the tracer substance is being used.
• Aggressive individuals show less activity in the frontal lobes (rational thinking) compared to deeper brain regions (emotional responses), and it is an example.
• Explains why aggressive people struggle with reasoning and compromise with the given insight

fMRI Scan (Functional Magnetic Resonance Imaging)

• No Tracer: It does not require a tracer substance.
• Magnetic Pulses: Monitors magnetic pulses from metabolically active parts of the brain.
• Oxygen and Glucose: Detects oxygen and blood glucose levels.
• Brain Disorders: Used to identify brain areas involved in pain, anxiety, and mental health disorders.
• Clinical Use: Commonly used in hospitals to detect brain clots or tumors.
• Research: Giving participants stimuli and observing activated brain areas.
• Integrates brain studies aim to combine environmental influences, personality traits, and physiological responses.

Correlations

• Researchers look for correlations between physiological measures (heart rate, brain activity, skin activity) and behaviors.

Precision

• Sophisticated methods allow precise identification and measurement of these factors.

fMRI Study

• Examined differences in brain activation between people high in neuroticism versus those high in extroversion when exposed to positive and negative images.
• Procedure: Participants were shown sad (negative) and happy (positive) pictures.
• Neuroticism: Higher frontal lobe activation in response to negative images.
• Extroversion: Higher frontal brain region activation in response to positive images.
• Personalities influence how individuals process stimuli and it is an interpretation.
• Extroverts may have a bias to process positive images more strongly, while those high in neuroticism may focus more on negative images resulting in a bias.
• Neuroticism relates to negative emotionality, and extroversion relates to positive emotionality.

Hormones

• Chemicals affect nerve cells and influence behavior and personality

Hormones Key Facts

• They affect nerve cells far from their origin, stimulating neurons throughout the body
• Present in both males and females, but in different concentrations where males from 300-1000 ng/dL, females roughly 30 ng/dL for Testosterone levels.
• Associations: Linked to aggression, risk-taking, and competition.
• High levels associated with people assaulting others, drug abuse, and alcohol abuse which are behavioral correlates,
• Cortisol, a stress hormone: Released as part of the fight-or-flight response.
• Effects: Prepares the body to act, increases heart rate, and stimulates muscle growth.
• Severe stress and depression can deplete cortisol levels which result in Dysregulation.
• Low levels are correlated with impulsivity and law-breaking behaviors, possibly due to a compromised ability to generate appropriate cortisol responses.
• Oxytocin:"Love Hormone": Linked to trustworthiness and morality.
• Facilitates bonding between mother and child.
• Is present during sexual activity and peaks after orgasm in women during Sexual Response.
• Women are able to achieve bonding and cooperation do to Approach behavior.
• Morality: Linked to the sense of right and wrong and the ability to trust others.

Eysenck's Theory of Personality

• Personality traits have biological substrates, focusing on extroversion, neuroticism, and psychoticism.
• Introverts/ Extroverts manifest different levels of cortical arousal with Extroversion being talkative, more social, but easily bored.
• Introversion is quiet, withdrawn, and likes spending time alone.
• Reactivity in extroverts and introverts are more reactive to moderate levels of activity, versus resting activity.
• Extroverts prefer higher levels of activation than introverts.
• Extroverts may prefer studying with loud music and multitasking, introverts would find this overstimulating.

Gray's BAS/BIS Theory

• Jeffrey Gray proposed an alternative model focusing on sensitivity, involving the Behavioral Activation System (BAS) and Behavioral Inhibition System (BIS).
• BAS: Components involve dopamine and the nucleus accumbens.
• Function: Responsive to rewards and cues of reward, regulating approach behavior.
• Approach Behavior: Propels the person us to get things, be motivated, and engage with the world.
• BIS: Inhibits actions, acting as "brakes."
• BIS Activation: Activated when criticized or scolded.
• Avoidance Behavior: Related to avoidance behavior.
• BAS and Extroversion: BAS closely relates to extroversion.
• BIS and Neuroticism: BIS closely relates to neuroticism.
• High BAS: More reward-dependent, take more risks, and are more impulsive.
• High BIS: Experience more negative pathology, depression, and anxiety.

Sensation Seeking

• It is a personality dimension theorized to have a strong basis in physiology.
• Originated as continuation of sensory deprivation studies by psychologist Heb
• Sensory Deprivation: People were deprived of any stimulation (nothing to do, see, or hear).
• Effects: Extremely torturous, leading people to want to do anything for stimulation.
• Optimal Level of Arousal: Individuals are motivated to maintain a balance in their level of stimulation.
• Sensory Deprivation: Being deprived of sensory stimulation, which the brain finds intolerable.
• Sensation Seeking: Seeking tension and stimulation, driven by the need to reach an optimal level of arousal.
• Under-Arousal: When environment does not provide enough stimulation, leading to increased activation (risky behaviors).
• Over-Arousal: Experiencing too much stimulation, leading to activities that reduce stimulation.
• Examples of Arousal-Seeking Behaviors: Jumping out of airplanes, gambling, taking risks, puzzles, and challenges.

Physiology of Sensation Seeking

• Is linked to the neurotransmitter monoamine oxidase (MAO) in the brain.
• MAO as a "cleaning agent" in the synapse
• Deactivating leftover neurotransmitters and stopping signals from being sent repeatedly.
• High sensation seekers tend to have lower MAO levels, leading to a need for more stimulation.
• Monoamine Oxidase (MAO): Neurotransmitter that serves as a cleaning agent in the synapse, deactivating leftover neurotransmitters.
• Pre-Synaptic Neuron: The neuron that sends a message.
• Post-Synaptic Neuron: The neuron that receives a message.
• Synaptic Cleft: The space occurs between the pre-synaptic and post-synaptic neurons where neuronal communication.
• Neurotransmitters: Then chemicals transmit signals from the pre-synaptic neuron to the post-synaptic neuron.
• Synapse: The point of connection between two neurons where neurotransmitters are released.
• High Sensation Seekers: Have low levels of MAO and require more stimulation to reach their optimal arousal level.
• Low MAO Levels: Result in needing external stimulation to achieve optimal arousal.
• High MAO Levels: Signals passing on are reduced, reducing the need for external stimulation.
• Clears neurotransmitters quickly, reducing signal potential and is High MAO Level effect on neurotransmition.
• Leaves more neurotransmitters in the synapse, prolonging signal is a low MAO level on neutotransmission.
• High MAO is Low Sensation Seeking Tendency.
• Prolonging sign is a high sign in sensation seeking tendency.

Key Neurotransmitters

• 3-dopamine, serotonin, and norepinephrine
• All play key roles in personality.
• Dopamine associates with reward and pleasure.
• Serotonin links with mood regulation and inhibition.
• Norepinephrine contributes to the fight-or-flight response and heart rate regulation .
• Dopamine controls reward and pleasure systems in the brain.
• Associations includes feelings of enjoyment and reinforcement to motivate behavior.
• Activities such as food, sex, and drugs increase dopamine levels.
• Immediate display of aggression can impact dopamine levels.
• Drugs like cocaine and methamphetamine operate on dopamine systems, potentially damaging the brain's ability to synthesize dopamine
• Drug addicts experience low dopamine levels during withdrawal, making coping difficult.

Serotonin

• Involved in mood regulation, appetite control, and inhibition of aggressive behaviors.
• Commonly called the "feel-good hormone."
• About 80% is found in the gut.
• Regulates body temperature and frontal brain activity.
• Plays a role in stopping oneself from doing something attractive but dangerous.
• Low levels link to criminal behavior and arson.
• Predators use serotonin to wait for the proper time to pounce and attack a prey.

Norepinephrine (Noradrenaline)

• Activated during the fight-or-flight response.
• Associations: Regulates heart rate and attention.
• Sympathetic Nervous System: Increases heart rate when excited, scared, or anxious.
• Stress Hormone: Impacts the amygdala, regulating attention and responses to the environment.
• Physiological Effects: Increases heart rate, triggers glucose release, and increases blood flow to muscles.

Cloninger's Model of Personality

• Model of personality based on the interaction of dopamine, serotonin, and norepinephrine (monoamines).
• Linked these neurotransmitters to specific personality traits where dopamine to novelty seeking, serotonin to harm avoidance, and norepinephrine to reward dependence.
• Monoamines are dopamine, serotonin, and norepinephrine.
• Novelty Seeking: Linked to low levels of dopamine; individuals seek new experiences and thrills.
• Harm Avoidance: Connected to abnormal metabolism of serotonin; individuals tend to be cautious, shy, and inhibited.
• Reward Dependence: Associated with low levels of norepinephrine; individuals are persistent, organized, and put in more effort to gain rewards.
• The personality trait of seeking new experiences, taking risks, needing thrills which is with Novelty Seeking dopamine trait.
• Cautious, shy, and inhibited links to Harm Avoidance serotonin nuerotransmitter.

Morningness and Eveningness

• Personality differences are influenced by underlying biological rhythms, such as the sleep-wake cycle (circadian rhythms).
• These rhythms fluctuate around a 24-hour cycle.
• Are measured by body temperature and endocrine secretion rates, especially melatonin.
• Temporal isolation studies, conducted in labs without external clues, reveal variations in individuals' sleep-wake cycles.
• Circadian Rhythm: A biological rhythm that fluctuates around a 24-hour cycle.
• Temporal Isolation Studies: Studies conducted in labs without external clues to observe natural sleep-wake cycles.
• Morning Types: hit their peak body temperature earlier in the day and get sleepy earlier.
• Evening Types: Individuals with longer circadian rhythms who are more alert and productive in the evening.
• Sleep-Wake Cycle: Varies considerably, from as short as 16 hours to as long as 50 hours, with an average of 24-25 hours.
• Mismatch: Differences in circadian rhythms can lead to conflicts.
• Shorter ythm is an Early riser with morning traits.
• Longer rythm is More alert in the evening, enjoys evening activities.

Brain Asymmetry

• The tendency for one side of the brain to be more active than the other.
• Measuring brain wave activity with EEG/ Electroencephalography
• Left Frontal EEG: Positive people who tend towards optimism and experiencing positive emotions.
• Right Frontal EEG: Pessimistic people.
• Affective Style: Individual's tendency to experience positive or negative emotions.
• Brain Acitivity style in the Left with positive, is Optismistic with postive emotions.
• Brain Acitivity style in the Right with negative, is pessimisism.

Evolutionary Theory

• Guiding principle in biology and psychology.
• Synthesizes modern psychology with evolutionary biology, offering insights into human nature, sex differences, and individual differences.
• Evolutionary Theory: Foundations that make modern biology.
• Natural Selection: Traits that enhance survival and reproduction are more likely to be passed on, introduced by Charles Darwin.
• Evolutionary Psychology: Applying biology to explain human behavior.
• Human Nature: Aspects that make everyone all the same.
• Sex Differences: Differences include men and women, especially in mating preferences.
• Individual Differences: variations among each individual.
• The Naked Ape is a recommended book for accessible understanding of human behavior that is is not aimed at a scientific audience
• Natural Selection: Variations which provide advantages for survival, leading to higher representation of those traits
• A variation is a difference that arises naturally within a population.
• Natural Selection - Adaptation: Traits enhance survival and reproduction which become more common.
• Natural Selection - Selection: Successful traits are selected over time, increasing their prevalence.
• Change that takes over time and adaptation to the environment are key features of evolution.
• Hostile Forces of Nature-Adaptations are solutions to drought, competitors, and natural disasters which impede survival.
• Innate Solutions to survival and reproductive issues are Adaptations to ancestory over time.
• the adaptations on barnacle goose that survive the jump from high cliffs, is an example.
• Barnacle goose nest on cliffs to avoid predators, food scarcity forces food scarcity forces goslings to jump shortly after hatching, and it is an example for sexual selecton
• Where traits evolve to enhance mating success, directly contribute to survival and it is a definition
• The elaborate plumage of a peacock attracts mates but also being a more visible target for predators, is the peacock example
• Ensuring the organism finds a mate and passes on its genes are the sexual selection focus.
• Members of the same sex competes for access to mates via intra competition.
• Male deer using antlers compete for mating rights so Inter-Sexual Selection
• Members of one sex choose mates based on preferred traits where peacocks prefer males with plumage which is Inter-sexual selection
• Total of classical fitness with the equivalent of own offspring the number of support is Inclusive Fitness.
• Formula is Personal Reproductive Success + Reproduction of Genetic Relatives (weighted by genetic relatedness).
• Improving overall genetic success by bring cooperative and helping related individuals is the Inclusive Fitness Concept.
• Example: Where scenarios are where participants saving in grandmom, father, cousin, or sibling is evolutionary study
• There has to be a preference of choice in reproductive and genetic relatedness in results.
• The need is to belong where fundamental human desire is for acceptance the desire is rooted the evolutionary of group survival.

Comparison of Natural and Sexual Selection

• Survival and reproduction which occurs over time and the adaptive value for natural or sexual selections.
• Adaptation is inclusive that is the the the relatives (weighted to gentic)
• "Cottage" is evolutionary, but may need a certain amount love and age and is a grandma choice
• 3rd grade or cousin - family dynamic has certain preference
• Implications - evolution maximizes survival
• The Evolutionary has a desire to belong within adaptation of a group that can be accepted

The Scenario

• Participants are presented with a scenario, such as a fire during a family reunion with you can only save one soul.

The Options

• Choices included individuals with varying degrees of genetic relatedness/reproductive potential, such as: A:91 yr/o grandma, B- 20 yr/o 3rd cousin, C: Father, D: old sibling

Expected Outcome

• Participants most likely to save individual with highest reproductive potential and closest genetic relationship. The old sibling

Grandmom

• has limited reproductive value

3rd Cousin

• distant genetic relationship

Father

• has already been reproduced, where sibling had more reproductive potential

Sibling

• high reproductive with 50% genes. The choices, however affect evolutionary measure which will maximize the survival of offspring and relays

Adaptive Motive

• The innate is from being accepted for the affiliation/evolutary
• Safety sharing and resources which cooperates huntermotive Alturism is to benifit and that's is inclusive theaty
• The emotions provide an evolutionary pass which is a univesal motion

Universal Emotions

• Suggests certain evolutions have served in evolutionary past Joy Reinforcing to be safe with danger

Adaptive value helps understand evolutay to understand change

• The sucess helps with mechanisim over time
• All Mechanisim assuming the proper help

Alalysis

• at the human to grpup to help behavior

"Survival in tribal"

• In early individual suvival twings of entrity, by fostering inter dependsce Moderny socitery less depondence from ancestors -

The "to bing"

• despite co- dependence/string groups while protect with others.
• Surivval no sticrly but the innatrve still exist
• Helping, that has selifish in motives - as a benifit that they been in group is from altruisim
• Debate Alturim if has selfless, help with self

The Altirim towards genetic compared relations, Indictations on the "subitles"

Facial - alter the trust that has photoes

Famiky the named in likely behavior even though stragers, For Inclusion - help, to helped in group Coopoeration " help the help to provide what have The emotions had time, acrrosd modern to ancient Ancient- braon likely the pre mammal Among the family

• coincity group from social membership The group to survuve has been valuely

Human Emotion

• best adjust to live to hunting They ensure serve the survivers - reguate by help
• Prevent the harm to feel to help move
• emotions
• Expernce to helper