Untitled Flashcard Set
Module 1.1: Interaction of heredity and environment
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Module 1.2: Overview of the Nervous System
A. Organization of the Nervous System
Know the functions and relationships of the following divisions:
1. Central nervous system (CNS): The brain and spinal cord. It processes information and coordinates responses.
2. Peripheral nervous system (PNS): All nerves outside the brain and spinal cord. It carries information between the CNS and the rest of the body.
3. Somatic nervous system: The division of the PNS involved in voluntary skeletal muscle movement and sensory information.
4. Autonomic nervous system (ANS): The division of the PNS that controls involuntary functions, such as heart rate, digestion, and breathing regulation.
5. Sympathetic nervous system: The division of the ANS that prepares the body for action during stress. It is associated with the fight-or-flight response.
6. Parasympathetic nervous system: The division of the ANS that calms the body and supports rest and digestion.
Key Concepts to Understand
1. What structures make up the central nervous system?
The brain and spinal cord.
2. What is the primary function of the peripheral nervous system?
It carries sensory information to the CNS and sends instructions from the CNS to the body.
3. How does the somatic nervous system differ from the autonomic nervous system?
The somatic system is involved in voluntary skeletal muscle movement, while the autonomic system regulates involuntary body functions.
4. What happens to the body when the sympathetic nervous system is activated?
Heart rate and breathing increase, pupils dilate, and energy becomes available for responding to danger or stress.
5. How does the parasympathetic nervous system restore the body to a calmer state?
It generally slows heart rate and supports digestion and recovery after stress.
6. What is homeostasis, and how do the two autonomic divisions contribute to it?
Homeostasis is the maintenance of stable internal conditions. The sympathetic and parasympathetic systems adjust body functions to help maintain balance.
B. Types of Neurons
1. Sensory (afferent) neurons: Carry information from sensory receptors toward the CNS.
2. Motor (efferent) neurons: Carry instructions away from the CNS to muscles and glands.
3. Interneurons: Process and relay information within the CNS.
Important Distinctions
Sensory neurons carry information toward the CNS.
Motor neurons carry instructions away from the CNS.
Interneurons process information within the CNS.
Memory trick: Sensory = in, motor = out, interneurons = in between.
Module 1.2: Overview of the Nervous System
A. Organization of the Nervous System
Know the functions and relationships of the following divisions:
1. Central nervous system (CNS): The brain and spinal cord. It processes information and coordinates responses.
2. Peripheral nervous system (PNS): All nerves outside the brain and spinal cord. It carries information between the CNS and the rest of the body.
3. Somatic nervous system: The division of the PNS involved in voluntary skeletal muscle movement and sensory information.
4. Autonomic nervous system (ANS): The division of the PNS that controls involuntary functions, such as heart rate, digestion, and breathing regulation.
5. Sympathetic nervous system: The division of the ANS that prepares the body for action during stress. It is associated with the fight-or-flight response.
6. Parasympathetic nervous system: The division of the ANS that calms the body and supports rest and digestion.
Key Concepts to Understand
1. What structures make up the central nervous system?
The brain and spinal cord.
2. What is the primary function of the peripheral nervous system?
It carries sensory information to the CNS and sends instructions from the CNS to the body.
3. How does the somatic nervous system differ from the autonomic nervous system?
The somatic system is involved in voluntary skeletal muscle movement, while the autonomic system regulates involuntary body functions.
4. What happens to the body when the sympathetic nervous system is activated?
Heart rate and breathing increase, pupils dilate, and energy becomes available for responding to danger or stress.
5. How does the parasympathetic nervous system restore the body to a calmer state?
It generally slows heart rate and supports digestion and recovery after stress.
6. What is homeostasis, and how do the two autonomic divisions contribute to it?
Homeostasis is the maintenance of stable internal conditions. The sympathetic and parasympathetic systems adjust body functions to help maintain balance.
B. Types of Neurons
1. Sensory (afferent) neurons: Carry information from sensory receptors toward the CNS.
2. Motor (efferent) neurons: Carry instructions away from the CNS to muscles and glands.
3. Interneurons: Process and relay information within the CNS.
Important Distinctions
Sensory neurons carry information toward the CNS.
Motor neurons carry instructions away from the CNS.
Interneurons process information within the CNS.
Module 1.3a: The Neuron and Neural Firing
A. Structure of the Neuron
1. Dendrites: Branch-like structures that receive signals from other neurons.
2. Cell body (soma): Contains the nucleus and maintains the neuron's basic functions. It integrates incoming signals.
3. Axon: Carries electrical impulses away from the cell body.
4. Myelin sheath: A fatty insulating layer around many axons that speeds up neural communication.
5. Axon terminals (terminal branches): The ends of an axon that release neurotransmitters to communicate with other cells.
6. Glial cells: Support, protect, and nourish neurons. Some glial cells produce myelin.
7. Synapse: The junction where one neuron communicates with another cell.
8. Synaptic cleft: The tiny gap between the sending neuron and the receiving cell.
9. Receptor sites: Proteins on a receiving cell that bind to specific neurotransmitters.
Direction of Information Through a Neuron
Dendrites → Cell body → Axon → Axon terminals → Synaptic cleft → Receptors on the next cell.
Key Concepts to Understand
1. How do dendrites and axons differ?
Dendrites receive incoming signals, while axons carry electrical impulses away from the cell body.
2. What is the function of the myelin sheath?
It insulates axons and allows neural impulses to travel faster.
3. How can damage to myelin interfere with neural communication?
Signals may travel more slowly or become disrupted, affecting movement, sensation, and other functions.
4. What roles do glial cells play in the nervous system?
They support and protect neurons, provide nutrients, maintain the neural environment, and form myelin around some axons.
B. Neural Firing and Action Potentials
1. Resting potential: The electrical charge difference across a neuron's membrane when it is not firing an action potential.
2. Action potential: A brief electrical impulse that travels down an axon when the neuron reaches threshold.
3. Threshold: The level of stimulation needed to trigger an action potential.
4. Depolarization: The membrane becomes less negative as positively charged sodium ions enter the neuron.
5. Repolarization: The membrane moves back toward its resting electrical state, largely as potassium ions move out of the neuron.
6. Refractory period: A short period after an action potential when the neuron cannot fire normally or needs stronger stimulation to fire again.
7. All-or-none principle: An action potential either occurs fully once threshold is reached or does not occur.
8. Excitatory signals: Signals that increase the likelihood that a neuron will reach threshold and fire.
9. Inhibitory signals: Signals that decrease the likelihood that a neuron will reach threshold and fire.
Key Concepts to Understand
1. What must happen before a neuron fires?
Incoming signals must bring the neuron to its threshold.
2. What occurs during depolarization?
Sodium ions enter the neuron, making the inside less negative and triggering the action potential.
3. What is the purpose of the refractory period?
It allows the neuron to reset and helps ensure that an action potential travels in one direction.
4. Why is neural firing described as an all-or-none response?
An action potential either occurs fully after threshold is reached or does not occur.
5. How does a neuron respond to a stronger stimulus if individual action potentials do not increase in strength?
The neuron can fire action potentials more frequently.
6. How do excitatory and inhibitory signals influence the likelihood of firing?
Excitatory signals increase the likelihood of firing, while inhibitory signals decrease it.
C. Neurotransmitters and Synaptic Transmission
1. Neurotransmitter release: When an action potential reaches the axon terminal, neurotransmitters are released into the synaptic cleft.
2. Receptor binding: Neurotransmitters attach to compatible receptors on a receiving cell and influence its activity.
3. Reuptake: The sending neuron takes neurotransmitters back up from the synaptic cleft.
4. Enzymatic breakdown: Enzymes break down neurotransmitters, helping end their effects.
5. Agonists: Substances that mimic a neurotransmitter or increase its effects.
6. Antagonists: Substances that block or reduce a neurotransmitter's effects, often by blocking its receptors.
Key Concepts to Understand
1. How do neurons communicate across the synaptic gap?
The sending neuron releases neurotransmitters, which cross the synaptic cleft and bind to receptors on the receiving cell.
2. What happens to neurotransmitters after they have delivered their message?
They may be taken back up through reuptake, broken down by enzymes, or otherwise cleared from the synaptic cleft.
3. How does an agonist affect neurotransmission?
It mimics or increases the effects of a neurotransmitter.
4. How does an antagonist affect neurotransmission?
It blocks or reduces the effects of a neurotransmitter.
5. How might a drug that prevents reuptake change neural communication?
Neurotransmitters remain in the synaptic cleft longer, potentially increasing or prolonging their effects.
D. Important Neurotransmitters
1. Acetylcholine (ACh): Muscle movement, learning, and memory.
2. Dopamine: Reward, motivation, learning, and movement.
3. Serotonin: Mood, sleep, and appetite.
4. Norepinephrine: Alertness and arousal.
5. GABA: The major inhibitory neurotransmitter in the brain; reduces neural activity.
6. Glutamate: The major excitatory neurotransmitter in the brain; increases neural activity and contributes to learning.
7. Endorphins: Help regulate pain and are involved in pleasure-related responses.
Important reminder: Neurotransmitters can have several functions, and their effects depend on the receptors and neural pathways involved.
E. The Endocrine System
1. Endocrine system: A system of glands that release hormones into the bloodstream to regulate body processes.
2. Hormones: Chemical messengers carried through the bloodstream to target cells and organs.
3. Pituitary gland: A gland regulated by the hypothalamus that releases hormones involved in growth and the control of other endocrine glands.
4. Hypothalamus: A brain structure that regulates hunger, thirst, body temperature, and homeostasis. It also connects the nervous and endocrine systems.
5. Adrenal glands: Glands above the kidneys that release hormones involved in stress responses.
6. Epinephrine (adrenaline): A hormone that prepares the body for action by increasing heart rate and making energy available.
Key Concepts to Understand
1. How does the endocrine system communicate with the body?
Glands release hormones into the bloodstream, which carries them to target cells.
2. How do hormones differ from neurotransmitters?
Hormones travel through the bloodstream and often have slower, longer-lasting effects. Neurotransmitters usually cross synapses and act more quickly.
3. Why do hormonal effects often last longer than neural signals?
Hormones circulate through the bloodstream and may remain active until they are broken down or removed.
4. What role does the hypothalamus play in coordinating nervous and endocrine activity?
It helps regulate hormone release through its control of the pituitary gland and helps maintain homeostasis.
5. How do adrenal hormones contribute to stress responses?
Epinephrine quickly prepares the body for action, while cortisol helps regulate the body's longer-term stress response.
Module 1.3b: Substance Use Disorders and Psychoactive Drugs
A. Substance Use and Addiction
1. Psychoactive drugs: Substances that affect the brain and change perception, mood, thinking, or behavior.
2. Substance use disorder: A condition involving a problematic pattern of substance use that causes significant impairment or distress.
3. Tolerance: A reduced response to a substance after repeated use, sometimes leading to the need for more to achieve the same effect.
4. Withdrawal: Physical or psychological symptoms that may occur when someone reduces or stops using a substance after the body has adapted to it.
5. Dependence: A state in which the body or brain has adapted to a substance, potentially causing withdrawal when its use stops. Physical dependence can occur without addiction.
6. Addiction: A condition involving compulsive substance use despite harmful consequences, often involving cravings and difficulty controlling use.
7. Drug cravings: Strong urges or desires to use a substance.
8. Expectancy effects: Effects influenced by what a person expects a substance to do.
Key Concepts to Understand
1. What distinguishes substance use from a substance use disorder?
Substance use simply means using a substance. A substance use disorder involves a problematic pattern that causes significant distress or interferes with daily life.
2. What happens when a person develops tolerance?
The same amount of a substance produces a weaker effect than before.
3. What is withdrawal, and why does it occur?
Withdrawal involves symptoms that may occur when substance use is reduced or stopped because the body or brain has adapted to the substance.
4. How can psychological expectations influence the effects of drugs?
Expectations can influence how someone perceives a substance's effects, including changes in mood or alertness.
5. Why can repeated drug exposure change behavior?
Repeated exposure can affect brain pathways involved in reward, learning, motivation, and self-control, potentially contributing to cravings and compulsive use.
B. Categories of Psychoactive Drugs
1. Depressants: Reduce neural activity and generally slow certain body functions. Examples include alcohol, barbiturates, and opioids.
2. Stimulants: Increase neural activity and arousal. Examples include caffeine, nicotine, cocaine, and amphetamines.
3. Hallucinogens: Alter perception and sensory experiences. An example is LSD.
Important note: Some drugs have complex effects and may not fit neatly into only one category.
C. Drugs and Neurotransmission
1. Mimicking neurotransmitters: A drug acts similarly to a natural neurotransmitter and activates certain receptors.
2. Blocking neurotransmitter receptors: A drug prevents a neurotransmitter from activating its receptor.
3. Increasing neurotransmitter release: A drug causes more neurotransmitter to be released into the synaptic cleft.
4. Blocking neurotransmitter reuptake: A drug prevents neurotransmitters from being taken back up, allowing them to remain in the synaptic cleft longer.
5. Changing normal signaling pathways: A drug alters how neurons communicate, changing brain activity and potentially affecting behavior.
Important Example: Cocaine
Cocaine interferes with the reuptake of neurotransmitters, including dopamine. This increases their presence in the synaptic cleft and can intensify reward-related signaling.
Module 1.4a: Neuroplasticity and Tools of Discovery
A. Biological Psychology
1. Biological psychology: The study of how biological processes, including the brain, nervous system, genes, and hormones, influence behavior and mental processes.
2. Biopsychosocial approach: An approach that explains behavior through the interaction of biological, psychological, and social-cultural factors.
3. Localization of function: The idea that particular brain regions have specialized functions.
4. Neuroplasticity: The brain's ability to change and reorganize its connections and functioning in response to experience, learning, or injury.
5. Neurogenesis: The formation of new neurons.
Key Concepts to Understand
1. Why do psychologists study the biological foundations of behavior?
To understand how the brain, nervous system, genes, and hormones influence thoughts, emotions, and actions.
2. How does the biopsychosocial approach explain behavior using biological, psychological, and social-cultural factors?
It considers biological factors such as genes, psychological factors such as thoughts, and social-cultural factors such as family and culture.
3. What is localization of function?
It is the idea that certain brain regions are specialized for particular functions, such as vision or movement.
4. How can experience physically change the brain?
Learning and repeated experiences can strengthen, weaken, or reorganize neural connections.
5. What is the difference between neuroplasticity and neurogenesis?
Neuroplasticity is the brain's ability to change and reorganize. Neurogenesis is the creation of new neurons.
6. How might the brain reorganize following injury?
Undamaged regions may sometimes adapt, and existing neural pathways may reorganize to help compensate for lost functions.
B. Brain Research Methods
1. EEG (electroencephalogram): Records electrical activity in the brain. It is especially useful for tracking the timing of brain activity.
2. CT scan: Uses X-rays to produce images of brain structure.
3. MRI (magnetic resonance imaging): Produces detailed images of brain structure using magnetic fields and radio waves.
4. PET scan (positron emission tomography): Uses a radioactive tracer to measure metabolic activity and identify patterns of brain activity.
5. fMRI (functional magnetic resonance imaging): Measures changes in blood oxygenation associated with brain activity.
6. Lesion studies: Examine how damage to specific brain regions affects behavior and functioning.
Key Concepts to Understand
1. Which techniques examine brain structure?
CT scans and structural MRI scans.
2. Which techniques provide information about brain activity?
EEG, PET scans, and fMRI.
3. Which method is especially useful for tracking the timing of electrical brain activity?
EEG, because it records electrical activity with excellent temporal resolution.
4. What can psychologists learn from studying brain lesions?
They can investigate how damage to particular brain regions affects behavior, helping identify the functions those regions contribute to.
5. Why does brain activity associated with a behavior not necessarily prove causation?
A brain region may become active during a behavior without causing it. Other regions or processes may also contribute.
Module 1.4b: Brain Regions and Structures
A. Major Divisions of the Brain
1. Hindbrain: Contains structures involved in basic survival functions, balance, coordination, and aspects of arousal.
2. Midbrain: Involved in movement, visual and auditory processing, and aspects of alertness.
3. Forebrain: Involved in complex functions such as thinking, emotion, memory, sensory processing, and voluntary movement.
B. Brainstem and Related Structures
1. Medulla: Controls vital automatic functions, including breathing and heart rate.
2. Pons: Helps regulate sleep and arousal and contributes to movement coordination.
3. Reticular formation: A network involved in alertness, arousal, and maintaining consciousness.
4. Thalamus: Acts as a relay station for most sensory information, sending it to appropriate areas of the brain. Smell is the major exception.
5. Cerebellum: Helps control balance, coordination, and certain forms of motor learning.
Key Concepts to Understand
1. Why is damage to the medulla especially dangerous?
Because it controls vital automatic functions, including breathing and heart rate.
2. How is the cerebellum involved in performing complex movements?
It helps coordinate timing, balance, and precision, allowing movements to be smooth and controlled.
3. What is the role of the thalamus in sensory processing?
It relays most sensory information to the appropriate areas of the cerebral cortex for processing.
4. How is the reticular formation involved in consciousness and alertness?
It helps regulate arousal and wakefulness. Damage to important parts of this system can seriously affect consciousness.
C. Limbic System and Associated Structures
1. Amygdala: Involved in processing emotions, particularly fear and the detection of emotional significance.
2. Hypothalamus: Regulates hunger, thirst, body temperature, and homeostasis. It also helps control the endocrine system through the pituitary gland.
3. Hippocampus: Important for forming new explicit memories, including facts and events.
4. Pituitary gland: Releases hormones involved in growth and helps regulate other endocrine glands under the control of the hypothalamus.
5. Limbic system: A group of interconnected brain structures involved in emotion, motivation, learning, and memory.
Key Concepts to Understand
1. Which structure is especially associated with fear and emotional processing?
The amygdala.
2. Which structure helps regulate hunger, thirst, body temperature, and homeostasis?
The hypothalamus.
3. Which structure is particularly important for forming new explicit memories?
The hippocampus.
4. How does the hypothalamus interact with the pituitary gland?
The hypothalamus regulates the pituitary gland, helping control hormone release and maintain homeostasis.
5. How do emotion, motivation, and memory involve multiple interconnected brain areas?
Different brain regions work together. For example, the amygdala contributes to emotional processing, the hippocampus contributes to memory, and the hypothalamus contributes to motivation and bodily regulation.
D. Cerebral Cortex
1. Frontal lobe: Planning, decision-making, voluntary movement, and executive functioning.
2. Parietal lobe: Processing body sensations and spatial information.
3. Occipital lobe: Visual processing.
4. Temporal lobe: Hearing, language comprehension, and aspects of memory.
E. Specialized Cortical Areas
1. Motor cortex: Located in the frontal lobe; controls voluntary movements of skeletal muscles.
2. Somatosensory cortex: Located in the parietal lobe; processes bodily sensations such as touch, pressure, temperature, and pain.
3. Visual cortex: Located in the occipital lobe; processes visual information.
4. Auditory cortex: Located in the temporal lobe; processes sound.
5. Broca's area: Usually located in the left frontal lobe; important for speech production.
6. Wernicke's area: Usually located in the left temporal region; important for language comprehension.
7. Association areas: Regions of the cerebral cortex that integrate information and support complex functions such as memory, reasoning, planning, and language.
Key Concepts to Understand
1. What would happen if the motor cortex were damaged?
A person may have difficulty controlling voluntary movements, potentially affecting particular body parts.
2. How does the somatosensory cortex process information?
It receives and processes information about bodily sensations, including touch and the position of body parts.
3. Why is the occipital lobe important for vision?
It contains the primary visual cortex, which processes visual information from the eyes.
4. What types of problems may occur following damage to Broca's area?
A person may have difficulty producing fluent speech, even if they understand much of what is said to them.
5. What types of problems may occur following damage to Wernicke's area?
A person may have difficulty understanding language and may produce fluent speech that lacks meaningful content.
6. How do association areas contribute to complex thought and behavior?
They combine information from different sources and support functions such as planning, reasoning, memory, and problem-solving.
F. Brain Damage and Behavior
Phineas Gage: A railroad worker who survived a serious accident that damaged parts of his frontal lobe. Historical accounts described changes in his personality and behavior.
Significance: His case helped researchers understand that the frontal lobes contribute to personality, decision-making, planning, and impulse control. However, one case study cannot establish every function of the frontal lobe by itself.
How do psychologists use case studies of brain damage to investigate localization of function?
They examine which abilities change after particular brain regions are damaged. These observations help researchers infer what those regions contribute to behavior.
Module 1.4c: Brain Damage and the Two Hemispheres
A. Responses to Brain Damage
1. Neuroplasticity: The brain's ability to change and reorganize neural connections in response to experience, learning, or injury.
2. Neurogenesis: The formation of new neurons.
3. Functional reorganization: The process by which brain regions or neural networks change their roles or organization, sometimes helping compensate for injury.
4. Neural compensation: When other neural pathways or brain regions help perform functions affected by damage.
5. Brain lateralization: The tendency for certain functions to be more strongly associated with one hemisphere than the other.
Key Concepts to Understand
1. How can undamaged brain regions sometimes compensate for injured areas?
Undamaged regions may reorganize their connections or take on some functions previously supported by the injured areas.
2. Why is recovery following brain damage not always possible?
Some damage is too extensive, and some neurons or specialized pathways cannot be fully replaced. Recovery depends on the location, severity, and type of damage.
3. How can experiences such as learning Braille or practicing a musical instrument reorganize brain activity?
Repeated practice can strengthen neural connections and change how brain regions respond to sensory information and movement.
4. How does neurogenesis differ from the formation of new connections between existing neurons?
Neurogenesis creates new neurons, while forming new connections changes the communication pathways among neurons that already exist.
B. The Divided Brain
1. Left hemisphere: Usually dominant for language in most people. It also contributes to logical reasoning and processes information from the right side of the body.
2. Right hemisphere: Often contributes strongly to spatial processing and aspects of attention and nonverbal processing. It processes information from the left side of the body.
3. Corpus callosum: A thick bundle of nerve fibers connecting the left and right cerebral hemispheres and allowing them to communicate.
4. Split-brain research: Research involving people whose corpus callosum was surgically severed, historically to help treat severe epilepsy, allowing scientists to study how the hemispheres function.
5. Contralateral processing: The principle that each hemisphere primarily receives sensory information from and controls movement on the opposite side of the body.
6. Lateralization of function: The specialization of one hemisphere for certain functions more than the other.
Key Concepts to Understand
1. What is the function of the corpus callosum?
It allows the left and right hemispheres to exchange information and coordinate their activities.
2. Why were split-brain operations historically performed?
They were performed to reduce the spread of severe epileptic seizures between the hemispheres.
3. What did Roger Sperry and Michael Gazzaniga discover through split-brain research?
Their research showed that the hemispheres can process information somewhat independently when the corpus callosum is severed. It also revealed differences in how the hemispheres handle certain tasks, including language.
4. How is visual information routed to the brain's hemispheres?
Visual information from the right visual field is processed primarily by the left hemisphere, while information from the left visual field is processed primarily by the right hemisphere. Each eye sends information to both hemispheres.
5. Why might split-brain patients identify an object with their left hand but be unable to name it?
An object presented in the left visual field is processed primarily by the right hemisphere. The right hemisphere can guide the left hand to identify or select the object, but if language is primarily controlled by the left hemisphere, the information may not reach the language areas needed to name it.
6. Why is the idea that individuals are simply "left-brained" or "right-brained" misleading?
Both hemispheres work together on most complex tasks. Although some functions are lateralized, personality and abilities cannot be divided into simple left-brained and right-brained categories.f Heredity and Environment
A. Nature, Nurture, and Evolutionary Psychology
1. Nature versus nurture: Nature refers to genetic influences, while nurture refers to environmental influences and experiences. Both shape behavior.
2. Natural selection: The process in which inherited traits that improve survival and reproduction become more common over generations.
3. Evolutionary psychology: The study of how evolution may have shaped behaviors and mental processes that helped our ancestors survive and reproduce.
4. Evolutionary adaptations: Inherited traits or behaviors that helped organisms survive and reproduce.
5. Behavior genetics: The study of how genes and environmental experiences influence behavior.
6. Genetic predisposition: An inherited tendency to develop a particular trait or behavior.
7. Heredity: The passing of genetic information from parents to offspring.
8. Environment: External influences and experiences that affect development and behavior, such as family, school, and culture.
Key Concepts to Understand
1. How does natural selection influence the development of certain behaviors over generations?
Behaviors that help organisms survive and reproduce may become more common over generations because the genes associated with them are passed down more often.
2. How do evolutionary psychologists explain behaviors that may have helped our ancestors survive?
They suggest that some behaviors developed because they helped our ancestors find food, avoid danger, cooperate, and care for offspring.
3. Why is the nature-nurture debate no longer considered an either/or question?
Genes and environmental experiences work together to influence behavior. Neither one alone explains everything.
4. How can genes and environmental experiences work together to influence behavior?
Genes may create a predisposition for a trait, while the environment influences how that trait develops. For example, someone may have a genetic tendency toward athletic ability but still needs practice to develop their skills.
5. How does natural selection differ from an individual's learned behavior?
Natural selection changes inherited traits across generations, while learned behavior develops through an individual's experiences during their lifetime.
B. Genetics and Individual Differences
1. DNA: The molecule that carries genetic instructions for building and maintaining an organism.
2. Genes: Sections of DNA that contain instructions for making proteins or regulating biological processes.
3. Chromosomes: Structures made of DNA and proteins that contain many genes.
4. Genome: An organism's complete set of genetic material.
5. Genetic mutations: Changes in DNA that may be harmful, beneficial, or have no noticeable effect.
6. Heritability: A statistical estimate of how much variation in a trait within a particular population is associated with genetic differences.
7. Gene-environment interaction: The way genes and environmental experiences work together to influence traits and behavior.
8. Epigenetics: The study of changes in gene expression that do not change the DNA sequence itself.
Key Concepts to Understand
1. What is the relationship between DNA, genes, and chromosomes?
DNA carries genetic information, genes are sections of DNA, and chromosomes are organized structures containing DNA and many genes.
2. What does heritability tell psychologists about differences within a population?
It estimates how much variation in a trait among people in a particular population is associated with genetic differences.
3. Why does a high heritability estimate not mean that the environment is unimportant?
Heritability describes differences within a population, not how much of one person's trait is caused by genes. Environmental experiences can still strongly affect a trait.
4. How might experiences influence the expression of genes?
Experiences such as stress, nutrition, and learning may affect whether certain genes are expressed more or less strongly.
C. Twin and Adoption Studies
Identical (monozygotic) twins: Twins who develop from the same fertilized egg and share nearly all their genetic variation.
Fraternal (dizygotic) twins: Twins who develop from two different fertilized eggs and share about half their genetic variation on average.
Twins raised together: Twins who share the same household and many environmental experiences.
Twins raised apart: Twins who grow up in different households and experience different environments.
Adoption studies: Studies that compare adopted children with their biological and adoptive relatives to investigate genetic and environmental influences.
Key Concepts to Understand
1. Why do psychologists study identical twins raised in different environments?
Because they share nearly all their genetic variation but experience different environments, researchers can investigate genetic and environmental influences on behavior.
2. How can twin and adoption studies help distinguish genetic influences from environmental influences?
Researchers compare similarities and differences among people who share different amounts of genetic material and different living environments.
3. What limitations do these studies have?
Researchers cannot randomly assign genes or childhood environments. Twins raised apart may still share similar experiences, so these studies cannot always prove that genes or environments directly caused a behavior.