Intro to Psychology
Personality is shaped by a complex interplay of biological factors. Twin studies reveal genetic influences on traits like extraversion and neuroticism, while infant temperament sets the stage for early development. These innate tendencies interact with our environment, creating unique personalities.
Evolutionary theory suggests personality traits evolved as adaptations for survival and reproduction. Meanwhile, neurobiology shows how brain structure and function, including neurotransmitters, influence our traits. This biological foundation combines with experiences to form our individual personalities.
Biological Influences on Personality
Twin studies and genetic influences
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- Minnesota Study of Twins Reared Apart (MISTRA) longitudinal study conducted by Thomas Bouchard and colleagues at the University of Minnesota examined identical twins separated at birth and raised in different environments
- Findings revealed significant similarities in personality traits between separated identical twins suggesting genetic influences on personality traits
- Extraversion, neuroticism, and openness to experience showed high heritability indicating a strong genetic component (e.g., identical twins raised apart had similar levels of extraversion)
- Environmental influences also play a role in shaping personality as unique experiences and social contexts contribute to individual differences (e.g., twins raised in different socioeconomic backgrounds)
- Nature and nurture interact to shape personality development through complex gene-environment interactions (e.g., a genetic predisposition for extraversion may be enhanced or diminished by social experiences)
Infant temperament in personality development
- Infant temperaments are innate, early-appearing individual differences in emotional reactivity and self-regulation that influence personality development
- Thomas and Chess's New York Longitudinal Study (NYLS) identified three main temperament categories:
- Easy temperament characterized by positive mood, adaptability, and regular sleep and eating patterns
- Difficult temperament marked by negative mood, intense reactions, and irregular sleep and eating patterns
- Slow-to-warm-up temperament exhibiting low activity level, mild reactions, and slow adaptability to change
- Temperament influences how infants interact with their environment shaping their experiences and development
- Goodness of fit, the compatibility between temperament and environmental demands, plays a crucial role
- Good fit promotes positive development and adaptability (e.g., an easy temperament in a supportive family)
- Poor fit may lead to adjustment problems and negative parent-child interactions (e.g., a difficult temperament in a chaotic household)
- Goodness of fit, the compatibility between temperament and environmental demands, plays a crucial role
- Temperament shapes and is shaped by experiences over time through bidirectional influences (e.g., a child's temperament elicits certain parenting behaviors, which in turn affect the child's development)
- Hormones play a role in temperament and personality development, influencing emotional reactivity and behavior
Evolutionary theory for personality traits
- Evolutionary perspective suggests that personality traits are evolved adaptations that enhanced survival and reproduction in ancestral environments
- Individual differences in traits reflect variations in adaptive strategies (e.g., extraversion may have been advantageous for forming social alliances)
- Evolved personality traits served specific functions:
- Extraversion facilitated seeking social dominance, forming alliances, and attracting mates
- Neuroticism promoted heightened sensitivity to threats and stressors, encouraging vigilance and caution
- Conscientiousness enabled planning, self-control, and adherence to social norms, facilitating group cooperation
- Balancing selection maintains genetic variability in personality traits within populations as different levels of a trait can be adaptive in different contexts (e.g., extraversion may be beneficial in social situations but detrimental in dangerous environments)
- Gene-environment interactions shape personality development as evolutionary predispositions interact with environmental factors
- Differential susceptibility hypothesis proposes that some individuals are more sensitive to both positive and negative environmental influences due to their genetic makeup (e.g., a child with a genetic predisposition for neuroticism may be more affected by stressful life events)
Neurobiological basis of personality
- Brain structure and function play a crucial role in shaping personality traits and individual differences
- The central nervous system, including the brain and spinal cord, is responsible for processing information and coordinating behavior
- The peripheral nervous system connects the central nervous system to the rest of the body, influencing physiological responses related to personality
- Neurotransmitters, chemical messengers in the brain, influence mood, behavior, and personality traits
- Neuroplasticity allows the brain to change and adapt in response to experiences, contributing to personality development over time
Key Terms to Review (18)
Neurotransmitters: Neurotransmitters are chemical messengers that facilitate communication between neurons in the nervous system. They are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron, triggering a response that can either excite or inhibit the target cell. Neurotransmitters play a crucial role in various psychological processes and behaviors, including cognition, emotion, and motor function.
Extraversion: Extraversion is a personality trait characterized by a focus on the external world, a tendency to be outgoing, sociable, and energetic. It is one of the five major dimensions of personality identified by trait theorists and is often contrasted with introversion. Extraverted individuals tend to be more assertive, enthusiastic, and enjoy social interactions, in contrast to introverted individuals who are more reserved and introspective.
Neuroticism: Neuroticism is a personality trait characterized by a tendency to experience negative emotions, such as anxiety, depression, and irritability. It is one of the five major dimensions of personality, as identified by the Five-Factor Model of personality. Neuroticism is a key concept in understanding personality, its biological underpinnings, and its relationship to various psychological and behavioral outcomes.
Heritability: Heritability is a statistical measure that quantifies the proportion of variation in a particular trait or characteristic that can be attributed to genetic factors within a population. It is a fundamental concept in the study of human genetics, intelligence, personality, and psychological disorders.
Central Nervous System: The central nervous system (CNS) is the primary information processing and control center of the body, consisting of the brain and spinal cord. It is responsible for integrating and coordinating the body's physiological processes, sensory inputs, and motor outputs.
Neuroplasticity: Neuroplasticity refers to the brain's ability to adapt, change, and reorganize itself in response to experience, learning, and environmental demands. It is a fundamental property of the nervous system that allows for the modification of neural pathways and synaptic connections throughout an individual's lifespan.
Peripheral Nervous System: The peripheral nervous system (PNS) is the part of the nervous system that is located outside the central nervous system (brain and spinal cord). It is responsible for transmitting information between the central nervous system and the rest of the body, including sensory information from the body to the brain and motor commands from the brain to the muscles.
Hormones: Hormones are chemical messengers produced by the endocrine system that regulate various physiological processes and behaviors in the body. They are responsible for coordinating and integrating the activities of different cells, tissues, and organs, playing a crucial role in both the endocrine system and the biological approaches to psychology.
Evolutionary Perspective: The evolutionary perspective is a framework for understanding human behavior and psychology through the lens of evolutionary theory. It posits that many of our cognitive, emotional, and behavioral traits have been shaped by natural selection over the course of our species' history, in order to enhance survival and reproduction.
Brain Structure: Brain structure refers to the physical organization and anatomy of the various regions and components that make up the human brain. This intricate network of interconnected structures is responsible for a wide range of cognitive, sensory, and motor functions that enable our complex behavior and experience of the world.
MISTRA: MISTRA is a neuroimaging technique that allows researchers to measure and analyze the magnetic properties of the brain. It is a non-invasive method that provides insights into the brain's structure, function, and activity, particularly in the context of biological approaches to psychology.
Openness to Experience: Openness to experience is a personality trait that reflects an individual's receptiveness to new ideas, emotions, and experiences. It is one of the five major dimensions of personality, as described by the Five-Factor Model of personality. This trait is characterized by a tendency to be curious, imaginative, and intellectually engaged, with a willingness to consider alternative perspectives and explore novel concepts.
Differential Susceptibility Hypothesis: The differential susceptibility hypothesis proposes that individuals have varying degrees of susceptibility to both positive and negative environmental influences. It suggests that some people are more sensitive to both beneficial and detrimental experiences, while others are less affected by environmental factors.
NYLS: NYLS, or the New York Law School, is a private law school located in New York City. It is known for its focus on practical legal education and its strong ties to the legal community in the city.
Goodness of Fit: Goodness of fit refers to the degree to which a statistical model or theory fits the observed data. It is a measure of how well the predicted values from a model or theory match the actual, observed values. A high goodness of fit indicates that the model or theory provides a good explanation for the data.
Temperament: Temperament refers to an individual's innate and biologically-based personality traits that are present from birth and shape their behavioral and emotional responses. It is considered a fundamental aspect of personality that is influenced by both genetic and environmental factors.
Gene-Environment Interactions: Gene-environment interactions refer to the dynamic interplay between an individual's genetic makeup and their surrounding environmental factors, which together shape various aspects of human development and behavior. This concept highlights how genetic predispositions can be influenced, amplified, or mitigated by environmental conditions.
Balancing Selection: Balancing selection is an evolutionary mechanism that maintains genetic variation within a population by favoring the persistence of multiple alleles at a given locus. It occurs when heterozygous individuals have a higher fitness than either homozygous type, leading to the maintenance of polymorphism in the population.