AP Psychology Unit 1

1.1 - Interaction of Heredity and Environment

Nature vs. Nurture: The Big Question

● Core Debate: How much of our behavior is due to inherited traits (nature)

versus environmental influences (nurture)?

Behavior and mental processes are shaped by both heredity and

environmental factors.

Heredity (Nature):

● Refers to genetic or inherited traits that influence physical, behavioral, and

mental characteristics.

Environmental Factors (Nurture):

● Refers to external influences, such as family, education, and experiences.

Note: Detailed information about genetics (like genotype, phenotype, DNA,

chromosomes, and gene expression) is not required for the AP Psychology

Exam.

Evolutionary Psychology

● Key Idea: Evolutionary forces have shaped human behavior to maximize

survival and reproduction.

● Focus: How natural selection has influenced our behaviors and mental

processes.

● Example: Evolutionary psychologists suggest that men are attracted to

younger women and women are attracted to older, more established men

because it increases the chances of successful reproduction.

Behavior Genetics

● Key Idea: Examines the role of both genetics and environment in shaping

behavior.

● Methods: Studies of twins (identical vs. fraternal) and adopted children to

identify genetic and environmental influences.

141.1 - Interaction of Heredity and Environment

Twin Studies

● Identical Twins: Develop from a single fertilized egg and share 100% of

their genes.

● Fraternal Twins: Develop from separate eggs and share 50% of their

genes, just like regular siblings.

● Key Findings: Identical twins are more alike in many traits (personality,

intelligence, interests) than fraternal twins, suggesting a strong genetic

influence.

The Minnesota Twin Project (Bouchard)

● Focus: Studied identical twins raised apart.

● Key Finding: Even when raised in different environments, identical twins

showed surprising similarities in IQ and personality, emphasizing the role

of genetics.

Adoption Studies

● Key Findings:

○ Adopted children's personalities are more similar to their biological

parents, indicating genetic influences.

○ Adoptive parents influence their children's attitudes, values,

manners, faith, and politics, showing environmental factors.

○ Adopted children often have higher IQs than their biological parents,

demonstrating the positive impact of a nurturing environment.

Heritability: The degree to which differences in traits within a group are due to

genetic differences, not environment.

● Key Point: High heritability means differences are mainly due to genes.

Low heritability means differences are mainly due to environment.

● Example: Identical twins have low heritability for most traits, since their

differences are largely environmental.

151.2 - Overview of the Nervous System

The Nervous System

● Central Nervous System (CNS):

○ Brain: The control center, responsible for thoughts, emotions, and

actions.

○ Spinal Cord: The information highway, transmitting messages

between the brain and the rest of the body.

● Peripheral Nervous System (PNS): The nerves that branch out from the

CNS to the rest of the body. Basically, connects the CNS to the rest of the

body.

Two Branches of the Peripheral Nervous System:

● Autonomic Nervous System (ANS): Regulates involuntary bodily

functions. Has two branches:

○ Sympathetic Nervous System: Activates the "fight-or-flight"

response in stressful situations, increasing heart rate, breathing, and

releasing adrenaline.

○ Parasympathetic Nervous System: Calms the body down after

stress, promoting rest and digestion (homeostasis).

● Somatic Nervous System: Controls voluntary muscle movement and

carries messages from the sense organs.

161.3 - The Neuron and Neural Firing

The Neuron

● Dendrites: Branch-like structures that receive messages from other

neurons.

● Soma (Cell Body): The neuron's life-support center, containing the

nucleus.

● Nucleus: Houses the cell's genetic material and decides whether the

neuron should fire.

● Axon: The long, thin fiber that carries electrical messages away from the

cell body.

● Myelin Sheath: A fatty layer that insulates the axon and speeds up the

electrical signal.

● Nodes of Ranvier: Gaps in the myelin sheath that allow the signal to

jump, further increasing speed.

● Schwann Cells: Special cells that form the myelin sheath in the peripheral

nervous system.

● Axon Terminal: The end of the axon where it connects with other neurons

or muscles.

● Terminal Buttons: Located at the axon terminal, these store and release

neurotransmitters.

Think of It Like This:

Imagine a neuron as a tiny messenger:

1. 2. 3. 4. 5. Dendrites receive a message like a

mailbox.

The soma (cell body) reads the message.

The axon is like a delivery truck,

carrying the message along a

highway (myelin sheath).

The terminal buttons deliver the message to another neuron (or muscle)

like a package.

Reuptake is like returning the delivery truck to the depot to pick up more

packages.

171.3 - The Neuron and Neural Firing

Two common types of brain cells:

● Neurons: Cells that transmit information.

● Glial Cells: Cells that provide structure, insulation, communication,

and help with waste transport.

● These cells are the foundation of the nervous system and are

essential for all behavior and mental processes.

● Reflex Arc in the Spinal Cord:

○ The spinal cord controls reflexes, which are automatic responses

to stimuli that don't require conscious thought.

○ Shows how neurons in the central and peripheral nervous

systems work together to respond to stimuli.

○ Three types of neurons involved:

■ Sensory Neurons (Afferent): Carry messages from the

senses to the central nervous system (CNS).

■ Interneurons: Found only in the CNS, act as messengers

between sensory and motor neurons.

■ Motor Neurons (Efferent): Carry messages from the CNS to

muscles and glands.

181.3 - The Neuron and Neural Firing

Neural Firing

The Action Potential: The Neuron's "Message"

1. Resting Potential (-70mV): The neuron is at rest, like a battery charged and

2. 3. 4. 5. 6. ready.

○ Inside: Mostly potassium ions (K+)

○ Outside: Mostly sodium ions (Na+)

Threshold (-55mV): The trigger point – if enough stimulation reaches the

neuron, it fires.

Action Potential: A brief electrical charge that travels down the axon, like a

wave.

Depolarization: Sodium gates open, and Na+ ions rush in, making the inside

of the neuron positive.

Repolarization: Potassium gates open, and K+ ions rush out, restoring the

negative charge inside.

Refractory Period: A short "recharge" time where the neuron cannot fire

again.

Note: The sodium potassium pump is outside the scope of AP Psychology so you

don't need to know how it works, but understand these big ideas in neural firing.

Key Points About Neural Firing

● All-or-None Principle: A neuron either fires completely or not at all. There

are no partial fires.

● Reuptake: The process where excess neurotransmitters are reabsorbed by

the sending neuron to be used again.

Neurotransmitters: Chemical Messengers

● Synapse: The tiny gap between neurons.

● Receptor Sites: Specialized places on the receiving neuron's dendrites

where neurotransmitters fit like keys in locks.

● Excitatory Neurotransmitters: Increase the chance the next neuron will fire.

● Inhibitory Neurotransmitters: Decrease the chance the next neuron will fire.

191.3 - The Neuron and Neural Firing

Neurotransmitters For AP Exam

● Dopamine:

○ Functions: Mood, emotion, reward, arousal.

○ Too Much: Schizophrenia, addiction

○ Too Little: Parkinson's disease

● Serotonin:

○ Functions: Mood regulation, appetite, sleep.

○ Too Much: Hallucinations

○ Too Little: Depression

● Norepinephrine:

○ Functions: Alertness, arousal, "fight-or-flight" response, mood.

○ Too Much: Anxiety

○ Too Little: Depression

● Glutamate:

○ Functions: Main excitatory neurotransmitter, learning, memory.

○ Too Much: Overstimulation, migraines, seizures

● GABA:

○ Functions: Main inhibitory neurotransmitter, calming the brain,

regulating sleep.

○ Too Much: Sleep and eating disorders

○ Too Little: Anxiety, epilepsy, insomnia

● Endorphins:

○ Functions: Pain relief, pleasure, stress reduction.

○ Too Much: Artificial highs, reduced pain sensitivity

○ Too Little: Possible link to addiction

● Acetylcholine (ACh):

○ Functions: Muscle movement, learning, memory, attention.

○ Too Much: Muscle spasms

○ Too Little: Alzheimer's disease

● Substance P: A neurotransmitter present in the brain and spinal cord

involved in transmitting pain signals.

201.3 - The Neuron and Neural Firing

Agonists vs. Antagonists: How Drugs Affect Neurotransmitters

● Agonists: Mimic neurotransmitters, enhancing their effects.

● Antagonists: Block neurotransmitters, inhibiting their effects.

The Endocrine System

● Key Features:

○ A slow-acting but longer-lasting communication system.

○ Works with the nervous system to maintain balance (homeostasis).

○ Supports the "fight-or-flight" response during stress.

● Major Glands and Hormones:

○ Pituitary Gland: The "master gland," controls other glands and

releases growth hormone.

○ Pineal Gland: Secretes melatonin, which helps with the timing of

your circadian rhythms which influences sleep-wake cycles.

○ Adrenal Glands: Located on top of the kidneys, these release:

i. ii. blood sugar regulation.

Other Important Hormones

● Leptin: Hormone secreted by fat cells. When abundant, it causes the brain

to increase metabolism and decrease hunger.

● Orexin: Hunger-triggering hormone secreted by the hypothalamus.

● Ghrelin: Hormone secreted by empty stomach signaling hunger to the

brain.

● PYY: Hormone secreted by the empty stomach signaling satiety (fullness)

to the brain.

● Oxytocin: Associated with bonding, empathy, and trust.

Adrenaline (epinephrine): For quick bursts of energy in

stressful situations preparing you to react.

Corticosteroids (cortisol): For longer-term stress responses and

211.3 - The Neuron and Neural Firing

Psychoactive Drugs and Their Effects

● Psychoactive Drugs: Chemicals that change perceptions, moods, and

consciousness.

● Tolerance: The diminishing effect of a drug with regular use, requiring

larger doses to achieve the same effect.

● Withdrawal: Unpleasant physical and psychological symptoms

experienced when stopping or reducing drug use.

● Dependence (Addiction): A compulsive craving for and use of a drug

despite negative consequences.

Types of Psychoactive Drugs

● Depressants: Slow down brain activity and bodily functions.

○ Alcohol: Reduces inhibitions, impairs judgment and memory, slows

reaction time.

○ Barbiturates: Sedatives or tranquilizers that can be highly addictive

and dangerous.

○ Opiates (e.g., heroin, morphine): Painkillers that are highly addictive

and can cause overdose.

● Stimulants: Increase brain activity and bodily functions.

○ Caffeine: Boosts alertness and energy.

○ Nicotine: Highly addictive, found in tobacco products.

○ Amphetamines: Suppress appetite, increase energy, but can lead to

anxiety and dependence.

○ Methamphetamine: A powerful, illegal stimulant with severe side

effects and high risk of addiction.

Stimulants and Hallucinogens

● Cocaine:

○ Effect: Intense euphoria and energy by blocking dopamine

reuptake.

○ Risks: Highly addictive, heart problems, paranoia.

● Ecstasy (MDMA):

○ Effects: Increased empathy, euphoria, energy.

○ Risks: Dehydration, overheating, high blood pressure, long-term

damage to serotonin neurons. 221.3 - The Neuron and Neural Firing

● Hallucinogens (Psychedelics): Alter perceptions, causing

hallucinations.

○ LSD: Powerful hallucinogen with unpredictable effects, can

cause intense emotions and "bad trips."

○ Marijuana (THC):

■ Effects: Relaxation, altered perception, impaired

coordination and memory.

■ Risks: Potential for addiction, impaired cognitive function,

lung damage (if smoked).

Why People Use Drugs

● Biological Factors: Genetic predisposition, changes in the brain's

reward system.

● Psychological Factors: Stress, trauma, mental health disorders.

● Social-Cultural Factors: Peer pressure, cultural norms, media

influence.

231.4 - The Brain

Studying the Brain

● Protection: The brain and spinal cord are cushioned by cerebrospinal

fluid and encased in meninges (protective membranes).

● Lesions and Ablation: Intentionally damaging or removing brain

tissue to study the effects on behavior. This is done in research and

sometimes to treat certain medical conditions.

Brain Imaging Techniques

● Electroencephalogram (EEG): Records electrical activity on the

brain's surface using electrodes placed on the scalp. Useful for

studying brain waves and identifying problems.

● Magnetic Resonance Imaging (MRI): Creates detailed images of

brain tissue using magnetic fields and radio waves. Helpful for

detecting tumors and injuries.

● Functional Magnetic Resonance Imaging (fMRI): Measures brain

activity by tracking changes in blood flow. Shows which brain areas

are active during tasks.

● Positron Emission Tomography (PET): Uses a radioactive tracer (like

glucose) to reveal brain activity and metabolism.

● Computerized Tomography (CT): Creates cross-sectional images of

the brain (and body) using X-rays. Good for seeing bone structures.

Brain Stimulation Therapies

● Deep Brain Stimulation (DBS): An electrode implanted in the brain

delivers electrical impulses to specific areas, used to treat conditions

like Parkinson's disease.

● Transcranial Magnetic Stimulation (TMS): A noninvasive method

using magnetic fields to stimulate or inhibit nerve cells in the brain,

used to treat depression and other disorders.

241.4 - The Brain

The Cerebral Cortex

● Divided into two hemispheres (left

and right) connected by the corpus

callosum, a bundle of nerve fibers

that enables communication

between them.

● Contains association areas

responsible for complex mental

processes like thinking, memory,

planning, and language.

● The Four Lobes and Their Functions:

○ Frontal Lobe:

■ Executive Functions: Decision-making, problem-solving, reasoning,

planning.

■ Personality: Influences traits like impulsivity and social behavior.

■ Motor Cortex: Controls voluntary muscle movements.

○ Parietal Lobe:

■ Sensory Processing: Receives and interprets touch, pressure,

temperature, and pain signals from the body.

■ Somatosensory Cortex: The main area for processing touch

sensations.

○ Occipital Lobe:

■ Visual Processing: Responsible for vision.

■ Primary Visual Cortex: Processes basic visual information from the

eyes.

■ Visual Association Cortex: Interprets visual information to recognize

objects and understand the visual world.

○ Temporal Lobe:

■ Auditory Processing: Responsible for hearing.

■ Wernicke's Area: Crucial for understanding language (located in the

left temporal lobe).

■ Right Temporal Lobe: Processes music and tonal changes.

■ Lower Temporal Lobe: Involved in some visual processing, like

recognizing patterns.

● Agnosia: A condition where damage to the temporal lobe makes familiar

objects unrecognizable.

251.4 - The Brain

The Brainstem

● Function: Controls essential life-supporting functions.

● Key Structures:

○ Medulla: Regulates heart rate, breathing, digestion,

swallowing, and sneezing. Think of it as the brain's autopilot.

○ Pons: A bridge that relays information between the brainstem

and higher brain regions (cerebellum and cortex).

○ Reticular Formation: A network of nerves involved in:

■ Arousal: The state of being awake, alert, and attentive.

■ Pain Modulation: Helps control the intensity of pain

signals.

○ Reticular Activating System (RAS): A part of the reticular

formation that regulates the sleep-wake cycle and filters

sensory input.

The Cerebellum and Limbic System

Cerebellum:

● Function: Coordinates fine motor movements, balance, and posture.

Think of it like the brain's athlete.

261.4 - The Brain

Limbic System: Often called the "emotional brain," it plays a key role in

memory, emotions, and drives.

● Thalamus: The brain's sensory switchboard. All sensory information

(except smell) passes through the thalamus before being sent to other

areas for processing.

● Hippocampus: Essential for forming and retrieving long-term memories,

as well as spatial navigation (knowing where you are).

● Amygdala: The emotional center, especially involved in fear, aggression,

and emotional memories.

● Hypothalamus: Regulates the body's internal state (homeostasis) by

controlling:

○ Hunger and thirst

○ Body temperature

○ Sleep-wake cycles

○ The endocrine system (hormone release)

○ Lateral Hypothalamus: Triggers feelings of hunger.

○ Ventromedial Hypothalamus: Signals fullness or satiety.

More Brain Structures and Functions

● Basal Ganglia:

○ Functions: Motor control, cognition (pleasure, motivation, learning,

reward).

○ Dopamine Connection: The basal ganglia are involved in releasing

dopamine, a neurotransmitter associated with pleasure and reward.

● Language Areas (Left Hemisphere):

○ Wernicke's Area: Understanding language (spoken and written).

○ Broca's Area: Producing speech.

● Hemispheric Specialization:

○ Left Hemisphere: Language, logic, analysis.

○ Right Hemisphere: Spatial reasoning, creativity, facial recognition.

● Brain Plasticity (Neuroplasticity): The brain's ability to change and adapt

throughout life. If one area is damaged, another area may take over its

function.

271.4 - The Brain

Key Figures in Brain Research

● Carl Wernicke: Discovered the area of the brain responsible for language

comprehension.

● Michael Gazzaniga & Roger Sperry: Pioneered research on split-brain

patients, revealing differences in function between the two hemispheres.

● Phineas Gage: A railroad worker whose personality changed dramatically

after a brain injury, providing early insights into the localization of brain

functions.

281.5 - Sleep

Sleep and the Brain

● Circadian Rhythm: Our 24-hour biological clock, regulated by the

hypothalamus. It controls sleep-wake cycles, body temperature, and other

bodily functions.

● Sleep Cycle: Each cycle lasts about 90 minutes and includes different stages

of sleep, including REM (rapid eye movement) sleep when most dreaming

occurs.

Measuring Sleep: EEG and Brain Waves

● Electroencephalogram (EEG): Records brain waves using electrodes placed

on the scalp. Different sleep stages have distinct brain wave patterns:

○ Awake/Alert: Beta waves

○ Relaxed: Alpha waves

○ NREM-1 (Light Sleep): Theta waves

○ NREM-2 (Sleep Spindles): Brief bursts of brain activity

○ NREM-3 (Deep Sleep): Delta waves

Stages of Sleep

1. 2. 3. 4. NREM-1 (Hypnagogic State): Transitional stage, relaxed but not fully asleep.

May experience hallucinations.

NREM-2: Deeper sleep with sleep spindles (bursts of brain activity).

NREM-3 (Deep Sleep): Slow-wave sleep, essential for physical restoration and

growth hormone release.

REM (Rapid Eye Movement): Brain activity increases, vivid dreams occur,

muscles are paralyzed.

Sleep Deprivation: The Consequences

Lack of sleep can lead to:

● Difficulty concentrating and reduced productivity

● Weakened immune system

● Increased risk of accidents

● Mood problems (irritability, anxiety)

● Hallucinations (in extreme cases)

291.5 - Sleep

Why Do We Sleep? Theories

● Protection: Sleep kept our ancestors safe from predators at night.

● Restoration: Sleep allows the body and brain to repair and rebuild.

● Memory Consolidation: Sleep helps strengthen and organize memories.

● Activation-Synthesis Theory: Dreams are the brain's attempt to make sense

of random neural activity during sleep.

● Growth: The pituitary gland releases growth hormone during sleep,

particularly in deep sleep.

Sleep Disorders

● Insomnia: Difficulty falling asleep or staying asleep.

● Narcolepsy: Sudden, uncontrollable sleep attacks, sometimes entering REM

sleep directly.

● Night Terrors: Abrupt awakenings with intense fear and panic, usually

occurring during deep sleep (NREM-3).

● Sleep Apnea: Repeatedly stopping and starting breathing while asleep.

● Sleepwalking (Somnambulism): Walking or performing complex behaviors

while asleep.

● REM Behavior Disorder: Acting out dreams due to a lack of muscle paralysis

during REM sleep.

301.6 - Sensation

Sensation

● Sensation: The process of detecting physical energy (stimuli) from the

environment and converting it into neural signals.

Thresholds: Limits of Sensation

● Absolute Threshold: The minimum amount of stimulation needed to detect

a stimulus half the time.

● Difference Threshold (Just Noticeable Difference - JND): The smallest

change in stimulation that’s needed to detect change half the time.

● Weber's Law: The difference threshold is proportional to the intensity of the

original stimulus. Example: It's easier to notice a small change in weight if

you're lifting a light object than a heavy one.

● Subliminal Threshold: A stimulus at a level at which the participant is not

aware of the stimulus being presented.

Other Key Concepts

● Signal Detection Theory: How we detect a faint stimulus (signal) in the

presence of background noise. It depends on factors like expectations,

motivation, and alertness.

● Sensory Adaptation: Our senses become less sensitive to a constant

stimulus over time. Example: Getting used to the smell of your own perfume.

● Habituation: A decrease in response to a repeated stimulus due to conscious

or unconscious learning. Example: Not noticing the ticking of a clock after a

while.

311.6 - Sensation

Structure of the Eye

1. 2. 3. 4. 5. 6. 7. Cornea: The clear, curved front of the eye. Bends light to begin focusing it.

Iris: The colored part of the eye, a muscle that controls the size of the pupil.

Pupil: The opening in the iris that lets light into the eye. Dilates (opens wider)

in dim light and constricts (gets smaller) in bright light.

Lens: A transparent, flexible structure that further focuses light onto the

retina. Changes shape to focus on objects at different distances

(accommodation).

Aqueous Humor: A watery fluid that fills the space between the cornea and

lens.

Vitreous Humor: A jelly-like substance that fills the main chamber of the eye.

Retina: The light-sensitive inner surface of the eye, containing photoreceptor

cells (rods and cones).

○ Fovea: The central point of the retina, where vision is sharpest and most

cones are located.

○ Optic Disc (Blind Spot): Where the optic nerve leaves the eye, creating

an area with no photoreceptors.

Photoreceptors: Rods and Cones

● Rods:

○ Detect black, white, and gray.

○ Responsible for peripheral and night vision (work in low light).

● Cones:

○ Detect color (red, green, blue).

○ Responsible for sharp, detailed vision and require bright light.

321.6 - Sensation

How We See:

1. 2. 3. 4. 5. Light enters the eye through the cornea and pupil.

The lens focuses the light onto the retina.

Rods and cones in the retina convert light into electrical signals.

These signals are sent through bipolar cells to ganglion cells.

Ganglion cells form the optic nerve, which carries the signals to the

brain for processing.

Vision: Color and Perception

Color Vision: How We Perceive Colors

● Hue: The dimension of color we experience (e.g., red, blue, green).

Determined by the wavelength of light.

○ Short Wavelength: Bluish colors

○ Long Wavelength: Reddish colors

● Intensity: The brightness of a color. Determined by the amplitude

(height) of the light wave.

○ High Amplitude: Bright colors

○ Low Amplitude: Dull colors

Vision Problems

● Nearsightedness (Myopia): Difficulty seeing distant objects clearly.

The eyeball is too long, causing light to focus in front of the retina.

● Farsightedness (Hyperopia): Difficulty seeing close objects clearly.

The eyeball is too short, causing light to focus behind the retina.

331.6 - Sensation

The Brain's Role in Vision

● Feature Detectors: Specialized neurons in the visual cortex that respond

to specific aspects of a visual scene (edges, angles, movement, faces).

● Parallel Processing: The brain processes different aspects of a visual

scene simultaneously (color, depth, movement, etc.).

Theories of Color Vision

● Trichromatic Theory (Young-Helmholtz): The retina has three types of

cones sensitive to red, green, and blue light. These cones work together to

produce our perception of all colors.

● Color Deficiency: A genetic condition where one or more types of cones

are missing or impaired, causing difficulty distinguishing certain colors.

● Opponent-Process Theory (Hering): We have three pairs of opponent

color receptors (red-green, blue-yellow, black-white). When one color in a

pair is stimulated, the other is inhibited. This theory explains afterimages.

● Color Constancy: The ability to perceive an object's color as relatively

constant even under varying lighting conditions.

Hearing: How We Perceive Sound

Sound Properties

● Frequency (Pitch):

○ Determined by the wavelength of the sound wave.

○ Measured in Hertz (Hz).

○ Long Wavelength: Low frequency (low-pitched sound)

○ Short Wavelength: High frequency (high-pitched sound)

● Intensity (Loudness):

○ Determined by the amplitude (height) of the sound wave.

○ Measured in decibels (dB).

○ High Amplitude: Loud sound

○ Low Amplitude: Soft sound

341.6 - Sensation

The Ear: Structure and Function

1. Outer Ear:

○ Pinna: The visible part of the ear, funnels sound waves into the ear

canal.

○ Ear Canal: Carries sound waves to the eardrum.

2. Middle Ear:

○ Eardrum (Tympanic Membrane): Vibrates in response to sound waves.

○ Ossicles (Hammer, Anvil, Stirrup): Tiny bones that amplify the

vibrations and transmit them to the inner ear.

3. Inner Ear:

○ Cochlea: A snail-shaped, fluid-filled tube containing hair cells that

convert vibrations into neural signals.

○ Semicircular Canals: Not involved in hearing; responsible for balance

and equilibrium.

○ Auditory Nerve: Carries neural signals from the cochlea to the brain.

Theories of Hearing

● Frequency Theory: The rate of nerve impulses traveling up the auditory

nerve matches the frequency of the sound, allowing us to perceive pitch.

Important Note: Damage to the hair cells in the cochlea is the most common

cause of sensorineural hearing loss (nerve deafness), which is often permanent.

351.6 - Sensation

Hearing: Theories and Beyond

● Place Theory: Different pitches (frequencies) activate specific areas on the

cochlea basilar membrane.

● Localization of Sound: We determine the location of a sound based on

the slight timing and intensity differences between our two ears.

Hearing Loss

● Noise-Induced Hearing Loss: Damage to hair cells in the cochlea due to

loud noises, often affecting high-frequency sounds first.

● Conduction Deafness: Hearing loss due to damage to the middle ear

(eardrum, ossicles), often treatable with hearing aids or surgery.

● Sensorineural Deafness (Nerve Deafness): Damage to the cochlea's hair

cells or the auditory nerve, usually permanent.

● Cochlear Implants: Electronic devices that bypass damaged hair cells and

directly stimulate the auditory nerve, providing a sense of sound.

Touch: The Somatic Senses

● Four Basic Sensations: Pressure, warmth, cold, pain.

● Pain:

○ A vital warning signal that something is wrong.

○ Congenital Insensitivity to Pain: A rare condition where individuals

cannot feel pain.

Factors Influencing Pain Perception

● Biological: Activity in the spinal cord, genetics (endorphin production),

brain interpretation.

● Social-Cultural: Presence of others, empathy, cultural expectations.

● Psychological: Attention to pain, past experiences, expectations of relief.

Gate Control Theory: Pain signals can be blocked ("gated") in the spinal cord

by competing signals from other senses or by brain signals.

361.6 - Sensation

Other Sensory Systems and Perception

Phantom Limb Pain:

● Sensation of pain in a limb that has been amputated.

● Likely caused by "cross-wiring" in the brain's somatosensory cortex

where areas responsible for the missing limb are taken over by

nearby areas.

Taste (Gustation):

● Taste Buds (Papillae): Tiny bumps on the tongue that contain taste

receptors.

● Five Basic Tastes: Sweet, salty, sour, bitter, umami.

● Chemical Sense: Taste receptors detect chemicals in food.

Smell (Olfaction):

● Process: Odor molecules enter the nasal cavity, bind to receptors,

and send signals to the olfactory bulb in the brain.

● Olfactory Bulb: Located near the limbic system (emotion) and

hippocampus (memory), explaining why smells can trigger strong

emotions and memories.

● Sensory Interaction: Taste and smell work together to create flavor.

Body Position and Movement:

● Kinesthesis: Sense of body position and movement of individual

parts.

● Vestibular Sense: Sense of balance and head position, located in the

inner ear.

This comprehensive set of notes covers fundamental topics in psychology. It begins by examining the interaction of heredity and environment (nature vs. nurture), detailing concepts like evolutionary psychology, behavior genetics, and findings from twin and adoption studies. Next, it delves into the nervous system, distinguishing between the Central (CNS) and Peripheral (PNS) Nervous Systems, and their subdivisions (Autonomic and Somatic). A significant portion is dedicated to the neuron and neural firing, explaining neuron structure (dendrites, axon, myelin sheath), the action potential, and the roles of key neurotransmitters (Dopamine, Serotonin, Acetylcholine, etc.). The endocrine system is presented as a slower, hormone-based communication system. The notes also cover psychoactive drugs, categorized by their effects (depressants, stimulants, hallucinogens), and factors influencing drug use.

The document then moves to the brain, describing its protective mechanisms, various imaging techniques (EEG, MRI, fMRI, PET, CT), and stimulation therapies (DBS, TMS). It details the functions of the cerebral cortex's four lobes (Frontal, Parietal, Occipital, Temporal), and important subcortical structures like the brainstem (Medulla, Pons, Reticular Formation), cerebellum, and limbic system (Thalamus, Hippocampus, Amygdala, Hypothalamus). Key figures in brain research and concepts like hemispheric specialization and brain plasticity are also introduced.

Sleep is explored through circadian rhythms, sleep cycles, and brainwave patterns (Beta, Alpha, Theta, Delta). It outlines the stages of sleep (NREM-1, NREM-2, NREM-3, REM), consequences of sleep deprivation, theories on why we sleep, and common sleep disorders (Insomnia, Narcolepsy, Night Terrors).

Finally, the notes cover sensation, defining absolute and difference thresholds, Weber's Law, and sensory adaptation. It provides a detailed account of the structure and function of the eye (cornea, iris, pupil, lens, retina, rods, cones) and hearing (outer, middle, inner ear, cochlea). Theories of color vision (Trichromatic, Opponent-Process) and hearing (Frequency, Place) are discussed, along with types of hearing loss. Other senses like touch (pain, vibration, temperature pain, perception of pressure.)