• The structure of the nervous system
• The nervous system controls your emotions, movements, thinking, + behavior.
• It is divided into 2 parts:
• The central nervous system the brain + the spinal cord
(nerves that run up + down the length of the back + transmit most messages b/w body + brain)
• The peripheral nervous system – the smaller branches of nerves that reach the other parts of the body.

• Neurons • Messages to + from the brain travel along the nerves, which are strings of long, thin cells called neurons.
Chemical electrical signals travel down the neurons.
• Transmission b/w neurons occurs when the cells are stimulated past a minimum point + emit a signal.
• They have 3 parts:
1. The cell body – contains the nucleus + produces the energy needed to fuel neuron activity.
2. Dendrites – Short, thin fibers that stick out from the cell body + receive impulses from other neurons + then send them to the cell body.
3. The axon – a long fiber that carries the impulses away from the cell body toward the dendrites of the next neuron. The axon terminal buttons are the hair-like ends of the axon.
• A white, fatty substance called the myelin sheath insulates + protects the axon for some neurons.

terminals of one neuron + the dendrites of another neuron. The space is known as the synapse.
• A neuron transmits its impulses or message to another neuron across the synapse by releasing chemicals called neurotransmitters.
• There are many different types of neurotransmitters – ex. Endorphins block pain, dopamine is involved in learning + movement, etc…).
• 3 types of neurons based on functions:
1. Sensory (or afferent) neurons – send messages from the sense organs to the brain.
2. Motor (or efferent) neurons – send signals from the brain to the glands + muscles.
3. Interneurons carry impulses b/w neurons in the body.

• Voluntary + involuntary activities
• Some actions your body makes in response to impulses from the nerves are voluntary
(scratching your head, turning a page, etc…), while others are involuntary (changes in heartbeat, dilation of pupils, etc…).
• The somatic nervous system is the part of the peripheral nervous system that controls voluntary activities.
• The autonomic nervous system is the part of the nervous system that controls involuntary activities. It has
2 parts:
• The sympathetic nervous system prepares the body for dealing w/ emergencies + strenuous activity.
• The parasympathetic nervous system works to conserve energy + to help the body recover from strenuous activity.

• Diagram of the human nervous system
Central
Nervous
System
Peripheral
Nervous
System
Somatic
Nervous System
(controls voluntary actions)
Autonomic
Nervous System
(controls involuntary actions)
Sympathetic
Nervous System
(prepares your body for stressful situations)
Parasympathetic
Nervous System
(calms your body down)

End Section 1

• The 3 main parts of the brain
• The hindbrain – located near the rear base of the skull that is involved in the basic processes of life. It includes the:
• Cerebellum – helps control posture, balance, + voluntary movements.
• Medulla – helps control breathing, heart rate, + many reflexes.
• Pons – functions as a bridge b/w the spinal cord + brain.
• The midbrain – small part of the brain above the pons that integrates sensory information + relays it upwards.

• The forebrain – covers the brain’s central core + is responsible for higher thinking processes. It includes the:
• Thalamus – integrates all sensory input except for smell.
• Hypothalamus – controls functions like hunger, thirst, sexual behavior, + reactions to change in temperature.
• The outer layer of the forebrain is the cerebral cortex. It gives us the ability to learn + store complex + abstract information.
• The inner layer is the cerebrum.
• The limbic system regulates our emotions + motivations. It includes the hypothalamus, thalamus, amygdala
(controls violent emotions like rage + fear), + hippocampus (helps w/ the formation of new memories).

• The lobes of the brain • The cerebrum is made up of 2 hemispheres or sides (right + left).
The hemispheres are connected by a band of fibers called the corpus callosum. Each hemisphere has deep grooves + is divided into 4 lobes
(regions):
• The occipital lobe is where visual signals are processed.
• The parietal lobe is concerned w/ information from the senses from all over the body.
• The temporal lobe is concerned w/ hearing, memory, emotion, + speaking.
• The frontal lobe is concerned w/ organization, planning, + creative thinking.
• The more sophisticated the movement, the more brain area involved in its control.

• The hemispheres of the brain
• The hemispheres of the brain are roughly mirror images + each has the same 4 lobes.
• Both sides complement + help each other.
The corpus callosum carries messages b/w them to jointly control human functions.
• Each side controls the movements of the other side of the body.
• The left side specializes in:
• Verbal (speaking, understanding language, reading, + writing)
• Mathematical
• Analytic (analyzing several pieces that make up a whole)
• The right side specializes in:
• Nonverbal (understanding simple sentences + words)
• Spatial
• Holistic (combining parts that make up a whole)

• Split brain operations communicate through the corpus callosum.
• Some people prone to severe seizures have surgery to sever the corpus callosum so that the 2 sides can no longer communicate to each other (this lessens the seizures).
• These people now have 2 independently operating brains.
• Studies have shown that these people’s abilities to complete certain tasks depends on which side must be used. They may be able to correctly identify an object held in one hand but not the other
(see p. 164).
• Split brain patients remained practically unchanged in intelligence, personality, + emotions.
• This research proves that each hemisphere is unique w/ specialized functions.

psychologists study the brain
• Recording brain activity:
• Electrodes are wires that can be inserted into the brain to record electrical activity. They are able to detect minute electrical changes that occur when neurons fire.
• An electroencephalograph (EEG), can look at activity of whole areas of the brain.
• Stimulating brain activity:
• Different parts of the brain can be stimulated by the use of electrodes to determine what functions various parts of the brain serve.
• Lets doctors know what parts of the brain need to be treated for various problems.
• Creating lesions:
• Scientists create lesions by cutting or destroying part of an animal’s brain. This can also show what parts of the brain are used for various activities. Lesions may also occur due to an illness.

• Studying people involved in accidents:
• Doctors can draw conclusions about the brain based on what parts of the brain were damaged + how the patient’s behavior changed.
• (1848) Phineas Gage had an iron pipe go through his skull during an explosion. It damaged the part of his brain which controls the formation of ideas. So while Gage had been known for the ability to plan and execute those plans well, afterwards, he wasn’t as much.
• Studying images:
• Different types of scans (CAT, PET,
MRI) can show brain deterioration, tumors, what parts of the brain are used in different activities, etc…
End Section 2

• The endocrine glands
• The 2 nd system for sending information to + from the brain (the 1 st is the nervous system).
• The endocrine system is a chemical communication system which uses hormones to send messages through the bloodstream.
• Hormones are chemical substances that carry messages through the body in blood + other body fluids (see p. 172 diagram).
• Although hormones circulate throughout the bloodstream, they are only received at the particular organ that they influence.
• Hormones affect your body in various ways – ex. growth of muscle + bone, energy levels, physical differences b/w boys + girls, influence moods + drives, etc…

the endocrine system + secretes a large # of hormones.
• Many of these hormones control the output of hormones by other endocrine glands.
• It acts as the master gland.
• The thyroid gland produces the hormone thyroxine which stimulates certain chemical reactions. Too little thyroxine makes people feel lazy + lethargic, but too much causes people to lose weight + sleep.
• When a person is angry or frightened the adrenal glands become active + release adrenaline + noradrenaline into the blood which cause heartbeat + breathing to . Helps generate extra energy to handle a difficult situation.
• The sex glands – testes in men (which produce sperm + testosterone) + ovaries in females
(which produce eggs + estrogen). Testosterone helps determine the sex of a fetus + estrogen helps w/ the reproductive cycle.

• Hormones vs. neurotransmitters
• Both work to affect the nervous system.
• The difference is that a neurotransmitter is released right beside the cell that it is to excite + a hormone is released into the blood
+ diffused throughout the body.
• The nervous system developed to send rapid + specific messages w/in thousandths of a second.
• The endocrine system developed to send slow + widespread communication which can take minutes to reach their destination + weeks or months to have their total effect.
End Section 3

• Nature vs. nurture
(heredity vs. environment)
• There has long been a debate over whether human behavior is instinctive (due to heredity) or learned (due to environment – things like family, culture, education, + individual experiences).
• Inherited + environmental factors act together in complicated ways.
• Heredity is the genetic transmission of characteristics from parents to their kids.
• Genes are the basic units of heredity. They are reproduced + passed from parent to child.

• Twin studies • One way to determine if a trait is inherited is to study identical twins.
• Identical twins develop from a single fertilized egg + share the same genes.
• Fraternal twins develop from 2 fertilized eggs + so their genes are no more similar than other siblings.
• The University of Minnesota has been studying identical twins who were separated at birth. By looking at their similarities, psychologists can better understand what behaviors must be caused by heredity instead of environment.
End Section 4

• Sleep
• A state of altered consciousness, characterized by certain patterns of brain activity + inactivity.
• Consciousness is a state of awareness, including a person’s feelings, sensations, ideas, + perceptions.
• People have altered states of consciousness,
or different levels of awareness.
• Until recently sleep was difficult to study.
W/ the invention of the EEG, psychologists can now study people’s sleeping patterns based on the electrical activity of the brain.

• Why do we sleep?
• Theories include:
• It’s a restorative – helps us “charge our batteries” + recover from stress.
• It’s a type of primitive hibernation – helps us conserve energy.
• It’s an adaptive process – kept primitive humans from wandering out at night + being vulnerable to animals w/ better night vision.
• It helps us clear our minds of useless information.
• We sleep to dream.

• Stages of sleep • Each cycle last about 90 min.
• At no point does the brain become totally inactive.
• Beginning:
• Body temperature + pulse rate .
• Breathing becomes slow + even.
• Body may twitch + eyes roll.
• Stage I: Lasts about 10 min.
• Pulse slows more + muscles relax.
• Breathing becomes uneven.
• Stage II: Lasts about 30 min.
• Your eyes roll slowly from side to side.
• Stage III:
• Transitional period b/w light + deep sleep.
• Stage IV: Time varies inversely w/ REM sleep.
• Deepest sleep – difficult to awaken.
• People may sleep talk/walk or wet the bed.
• Stage V: REM sleep.

• REM sleep • Characterized by rapid eye movement.
• Breathing becomes irregular.
• Levels of adrenal + sexual hormones in blood like you were involved in intensely emotional or physically demanding activity.
• Often face + fingers twitch, but large muscles in arms + legs are paralyzed.
• Brain waves resemble those of someone who is awake.
• Lasts from 15 min (early at night) to 45 min
(late at night).
• Seems to serve psychological functions like building efficient learning + memory processes.

• How much sleep do we need?
• Humans spend about 1/3 of their life asleep.
• Average amount needed varies based on age:
• Newborns: 16 hrs
• 16 yr olds: spend as much as 10-11 hrs
• Graduate students: 8 hrs
• 70 yrs + older: may only need 5 hrs
• Your circadian rhythm is a biological clock that is genetically programmed to regulate physiological responses w/in a 24-25 hr period.
• Operates even when normal day/night cues are removed.
• Different for everyone.
• Regulates times of day when we feel more/less alert.
• Blood pressure, heart rate, appetite, hormone secretion, sensory sharpness, etc… all follow our circadian rhythm.
• Doesn’t necessarily match the environment (ex. jet lag).

• Sleep disorders
• Insomnia – a prolonged + usually abnormal inability to obtain adequate sleep. Many causes (depression, drugs, etc) + forms (no sleep, interrupted sleep, etc).
• Sleep apnea – sleeping disorder during which the person has difficulty breathing while sleeping. Characterized by a specific type of snoring – lasts 10-15 seconds + ends suddenly. Person is actually choking due to a blocked breathing passage. Usually caused by physical problems (ex: obesity, enlarged tonsils etc). Affects 1 in 100 Americans – usually the elderly.
• Narcolepsy – sleeping disorder characterized by suddenly falling asleep or feeling very sleepy during the day. People w/ it are constantly tired + may have unusual sleep patterns + dreamlike hallucinations.

• Night terrors – sleep disruptions involving screaming, sweating, panic,
+ confusion. Unlike nightmares, people who suffer from terrors wake up w/ no memory of it.
• Sleepwalking – many causes, usually harmless. Associated more w/ children than adults. It is NOT dangerous to wake them.
• Sleep talking – harmless, many people sleep talk but don’t realize it.
Can carry on conversations or may only speak a word or two.

• Dreams • Most people can only recall a few of their dreams.
• 1 st few dreams of the night are usually vague thoughts left over from the day’s activities.
Later dreams become longer + more vivid + dramatic.
• You usually remember the last dream you have.
• Most dreams are about more commonplace events than the ones we remember.
• Content of dreams includes:
• Everyday activities.
• Commonplace settings.
• Large % of emotion in dreams is negative.
• Dreams do not happen in a split second; they correspond to a realistic time scale.

• Dream interpretation
• Practice dates back to 5000 B.C.
• Sigmund Freud believed that dreams may contain clues to thoughts the dreamer is afraid to acknowledge in his/her waking hours + that they have hidden meanings.
• He was the 1 st psychologist to study dreams thoroughly.
• Many psychologists do not accept this view + have different views about dream interpretation:
• Some follow Freud.
• Others state that dreams are useless
+ mean nothing.
• Others state they are used so we can recap what happened in our day + problem solve.
• The final group says they are there to help remove some unneeded memories.

• Day dreams • Require a low level of awareness + involve fantasizing while we are awake.
• Usually occurs when we’re in situations that require little attention or when we’re bored.
• Serves several useful purposes:
• Reminding or preparing us for events in the future.
• Improving creativity.
• Some psychologists believe they allow us to control our emotions.
End Section 1

• Hypnosis • A state of altered consciousness resulting from a narrowed focus of attention + characterized by heightened suggestibility to changes in behavior + thought.
• People who have been hypnotized can be made conscious of things they’re usually unaware of + unaware of things they’re usually aware of.
• Hypnosis is NOT a type of sleep – people who are hypnotized become highly receptive + responsive to certain stimuli. They can focus their attention on one tiny aspect of reality + ignore all others.
• The hypnotist induces a trance by slowly persuading a participant to relax + to lose interest in external distractions.
• The amount of time it takes to induce a hypnotic state varies.
• Anyone can resist hypnosis by refusing to open his/her mind to the hypnotist.

• Different theories about hypnosis
• Some think it isn’t a special state of consciousness, but the result of suggestibility.
• If people are given instructions
+ just try their hardest, they’ll be able to do anything hypnotized people can.
• Some think there is something special about the hypnotic state b/c people don’t initiate activities under hypnosis
+ are better at imagining + remembering things.
• Others believe that hypnotized people behave as they do b/c they’ve accepted the role of a hypnotized subject.

• Uses of hypnosis
• Entertainment
• Posthypnotic suggestion – a suggestion made during hypnosis that influences the participant’s behavior afterwards.
• Useful for quitting unwanted behaviors (ex: smoking, overeating, etc)
• Reduce pain – people have had surgery under hypnosis w/o anesthesia + reported feeling no pain.
• Used by therapists to reveal problems + recall memories.

• Biofeedback • The process of learning to control bodily states w/ the help of machines monitoring the states to be controlled.
• Used to teach people to control a variety of physiological responses (ex: brain waves, heart rate, blood pressure, sweat-gland activity, muscular control, etc).
• Machines tell people about very subtle moment-to-moment changes in the body.
People can then experiment w/ different thoughts + feelings while they watch how each affects their bodies.

• Meditation • The focusing of attention to clear one’s mind
+ produce relaxation.
• Been in practice around the world for thousands of years.
• 3 major approaches to meditation:
1. Transcendental meditation: involves sitting w/ eyes closed for 15-20 min + the mental repetition of a mantra.
2. Mindfulness meditation: involves focusing on the present moment.
3. Breath meditation: involves concentrating on one’s respiration.
• Researchers mostly agree that people can benefit from the type of systematic relaxation that meditation provides.
• Has been found to help lower blood pressure, heart rate, + respiration rate.
End Section 2

• Psychoactive drugs
• Interact w/ the central nervous system to alter a person’s mood, perception, + behavior.
• Range from stimulants like caffeine to depressants like alcohol.
• Drugs are carried by the blood + taken up in target tissues in parts of the body by acting like neurotransmitters + hooking onto the ends of neurons + sending out their own chemical messages. Ex. of messages:
• Alcohol molecules may tell a nerve cell not to fire. As more + more cells cease firing, the alcohol user becomes slower + may lose consciousness.
• LSD molecules may cause circuits in different areas of the brain to start firing together instead of separately, resulting in hallucinations.

• Marijuana • The dried leaves + flowers of Indian hemp
(Cannabis sativa) that produce an altered state of consciousness when smoked or ingested (can be cooked + eaten).
• It’s legally + morally acceptable in some societies where alcohol isn’t.
• Effects vary from person to person + may be pleasant or unpleasant.
• Not physically addictive, but may become psychologically addictive.
• Cases have been reported in which it appears to have helped bring on psychological disturbances in people who were already unstable before they used it.
• Studies suggest that it is more damaging to the lungs than cigarette use.
• Disrupts memory formation, making it difficult to carry out mental + physical tasks.
• Adults using it score lower than nonusers on academic achievement tests.

• Hallucinogens • Drugs that often produce hallucinations.
• Hallucinations are perceptions that have no direct external cause.
• Can be caused by hypnosis, meditation, certain drugs, withdrawal from certain drugs, psychological breakdown, lack of sleep, dreaming, + periods of high emotion or concentration.
• Hallucinogens (also called psychedelics) create a loss of contact w/ reality. They create a false body image + dreamlike fantasies.
• Best known is LSD – one of the most powerful drugs known. A “trip” on LSD lasts from 6-14 hrs.
During this time, a person can experience any # of perceptions, often intense + rapidly changing.
Sometimes it’s a terrifying experience. It impairs thinking, even though users may feel they are thinking more clearly than ever before. Panic attacks can be a side effect + sometimes people have flashbacks.

• Opiates • Produce pain reduction, euphoria (a pleasurable state somewhere b/w wake + sleep), + constipation.
• Also called narcotics.
• Includes opium, morphine, + heroin.
• Regular use can lead to physical addiction.
• An overdose results in a loss of control of breathing – user then dies from respiratory failure.

• Alcohol • The most widely used + abused mind-altering substance in the US.
• Encouraged by advertisements, social expectations, + traditions.
• Immediate effect is a general loosening of inhibitions.
• Although it appears to be a stimulant, it’s really a depressant that inhibits the brain’s normal functions.
• Effects depend on the amount + frequency of drinking, the drinker’s body weight, + other physical issues (other drugs in their system, food consumption, etc).
• Effects include slurred speech, blurred vision,
+ impaired judgment + memory.
• Permanent brain + liver damage + a change in personality can result from long-term heavy use.

• Drug abuse
+ treatment
• Most of us have taken a psychoactive drug – like caffeine or nicotine.
• Drug abusers are people who regularly use illegal drugs or excessively use legal drugs.
• Common reasons for taking drugs include to avoid boredom, to fit in w/ peers, to gain selfconfidence, to forget problems, to relax, or to feel good.
• Risks include addiction, death or injury from overdose, damage to health, legal consequences,
+ destructive behavior.
• Treatment for drug abuse usually involves the following 3 steps:
1. Must admit that he/she has a problem.
2. Must enter a treatment program +/or get therapy.
3. Must remain drug free.
• Many addicts suffer a relapse. Support groups can help prevent this.
End Section 3

• Sensation • Occurs anytime a stimulus activates one of your receptors (touch, sight, sound, taste, or smell).
• A stimulus is any aspect of or change in the environment to which an organism responds.
• A perception is the organization of sensory information into meaningful experiences.
• Your success in gathering information from your environment, interpreting this information, + acting on it depends on its being organized in ways you expect.
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• Psychophysics • Study of relationships b/w sensory experiences
+ the physical stimuli that cause them.
• The absolute threshold is the weakest amount of a stimulus required to produce a sensation.
• The level of stimulus that produces a positive response of detection 50% of the time.
• Absolute threshold for humans is:
• Seeing a candle flame 30 mi away on a clear night.
• Hearing a watch ticking 20 ft away.
• Tasting 1 teaspoon of sugar dissolved in 2 gal of water.
• Smelling 1 drop of perfume in a 3 room house.
• Feeling a bee’s wing falling 1 cm onto your cheek.
• The difference threshold is the smallest change in a physical stimulus that can be detected b/w
2 stimuli.
• Weber’s Law states that the larger or stronger a stimulus, the larger the change required for a person to notice that anything has happened to it.

• Psychologists focus on people’s responses to changes in stimuli b/c the senses are tuned to change.
• Senses are most responsive to or
+ to new events rather than ongoing, unchanging stimulation.
• This is b/c our senses adapt.
• There’s no sharp boundary b/w stimuli you can + can’t perceive.

• Signal-
Detection
Theory
• Studies the relations b/w motivation, sensitivity, + decision making in detecting the presence or absence of a stimulus.
• Detection thresholds involve recognizing some stimulus against a background of competing stimuli.
• Varying factors can affect our ability to detect certain stimuli, such as motivation, quantity + quality of competing stimuli, amount of time spent concentrating on a task, etc…
• So there is no single true absolute threshold for detecting a stimulus.
• Psychologists have identified 2 ways of processing stimuli (or “signals”):
• Preattentive process is a method for extracting information automatically + simultaneously when presented w/ stimuli.
• Attentive process is a procedure that considers only one part of the stimuli presented at a time.
End Section 1

• Vision • Most studied of all the senses – shows how important we think it is.
• Provides us w/ information about our environment – sizes, shapes, locations, textures, colors, + distances.
• Vision occurs when light enters the eye through the pupil (the opening in the iris that regulates the amount of light entering the eye) + reaches the lens (a flexible structure that focuses light on the retina). Once the lens has focused light on the retina (the innermost coating of the back of the eye, containing the light-sensitive receptor cells – rods + cones) the rods + cones w/in it change light energy into neuronal impulses which then travel along the optic nerve
(nerve that carries impulses from the retina to the brain) to the brain where they are routed to the occipital lobe.

• Light • Light is a form of electromagnetic radiation
(so are radio waves, microwaves, infrared radiation, UV rays, X-rays, etc…)
• Visible light can be observed w/ a prism.
Passing sunlight through a prism breaks the light into a rainbow of colors each comprised of light of different wavelengths. Prisms transmit light while other objects absorb + reflect light. The object’s color depends, in part, on the light that reaches our eyes.
• Ex. An apple reflects red light + absorbs all others.

• Color deficiency
• The cones in our retinas require more light than rods + work best in daylight. Only cones are sensitive to color. Rods work best at night + only see black + white.
• So when some or all of a person’s cones don’t function properly, he/she is colordeficient. Most color-deficient people see some color (Ex. They may have trouble distinguishing b/w red + green OR blue + yellow). Few people are totally color-blind.
Color deficiency affects about 1% of
American women + 8% of men. It’s a hereditary condition carried on the X chromosome.

• Binocular fusion
• B/c we have 2 eyes, the visual system receives 2 images. The process of combining the images received from the 2 eyes into a single, fused image is called binocular fusion.
• There is also a difference b/w the images on the retinas stimulating each eye called retinal disparity.
• Try holding your pen or pencil in front of your face. Close your left eye + look at it only w/ your right. Now quickly close your right eye and look at it only w/ your left. Do this several times.
• Retinal disparity is essential to our sense of depth perception. A large amount of retinal disparity tells the brain the object is nearby + a small amount tells it it’s far away.
• If your eyeballs are a little too long, you are nearsighted (can see objects nearby, but far away objects appear blurry). If they’re too short you are farsighted (can see objects far away, but objects nearby appear blurry).

• Hearing • Depends on vibrations of the air, called sound waves.
• Hearing occurs when sound waves pass from the air through various bones until they reach the inner ear, which contains tiny hair-like cells that move back + forth which change sound vibrations into neuronal signals that travel through the auditory nerve (the nerve that carries impulses from the inner ear to the brain, resulting in the perception of sound) to the brain.
• Loudness is determined by the amplitude, or height, of sound waves.
• Pitch depends on sound wave frequency, or the rate of vibrations.
• Sources of sounds can be located when your ears work together. Sounds that reach an ear a fraction of a second faster + are slightly louder, tell you what direction it came from.

• The pathway of sound
• The ear is designed to capture sound waves.
The outer ear receives sound waves + the earflap directs the sounds down a short tube called the auditory canal. The vibration of air (the sound wave) causes air in the auditory canal to vibrate which causes the eardrum to vibrate.
• The middle ear is an air-filled cavity w/ 3 tiny bones that vibrate when the eardrum vibrates + push against the cochlea.
• The cochlea makes up the inner ear. It’s a bony tube that contains fluids + neurons.
The pressure against it makes the liquid inside it move. The tiny hairs inside it pick up the motion. The hairs are attached to sensory cells which turn the sound vibrations into neuronal impulses which are carried by the auditory nerve to the brain.

• Deafness • There are 2 types of deafness:
• Conduction deafness occurs when anything hinders physical motion through the outer or middle ear.
• These people can usually be helped w/ a hearing aid.
• Sensorineural deafness occurs from damage to the cochlea, the hair cells, or the auditory neurons.
• These people cannot be helped w/ a normal hearing aid. They require special hearing aids that must be implanted in their ear.

• Balance • Our sense of balance is regulated by the vestibular system (the 3 semicircular canals that provide the sense of balance, located in the inner ear + connected to the brain by a nerve).
• The stimuli for vestibular responses include movements like spinning, falling, + tilting your body or head.
• Overstimulation can result in dizziness or motion sickness.
• Necessary to be able to walk or stand w/o stumbling.

• Smell + taste • Known as chemical senses b/c their receptors are sensitive to chemical molecules rather than light energy or sound waves.
• In order to smell something, the appropriate gaseous molecules must come into contact w/ the smell receptors in your nose. They enter your nose in vapors that reach a special membrane in the upper part of the nasal passages on which the smell receptors are located. These receptors send messages about smells from the nose to the brain through the olfactory nerve.
• In order to taste something appropriate liquid chemicals must stimulate receptors in the taste buds on your tongue. Taste information is relayed to the brain along w/ data about texture + temperature.
• There are 4 primary sensory experiences that make up taste: sour, salty, bitter, + sweet.
Temperature also influences taste.
• Much of what is referred to as taste is actually produced by the sense of smell.

• Skin senses • Receptors in the skin are responsible for providing the brain w/ at least 4 kinds of information about the environment: pressure, warmth, cold, + pain.
• Sensitivity to pressure varies from place to place in the skin (ex. Fingertips are more sensitive than the middle of the back).
• Pain makes it possible for you to prevent damage to your body – it’s an emergency warning system.
• Unlike most other senses, pain results from many different stimuli (ex. Intense pressure, bright lights, loud noises, intense heat, etc…).
• There are 2 types of pain sensations: sharp, localized pain you feel immediately + dull, generalized pain you may feel later.
• The Gate Control Theory of Pain states that we can lessen some pains by shifting our attention away from the pain impulses or by sending other signals to compete w/ the pain signals
(ex. Rubbing a stubbed toe).

• Body senses • Kinesthesis is the sense of movement + body position.
• It cooperates w/ the vestibular + visual senses to maintain posture + balance.
• It comes from receptors in + near the muscles, tendons, + joints.
• When any movement occurs, these receptors send messages to the brain.
• W/o these sensations, your movements would be jerky + uncoordinated.
End Section 2

• Perception information from the senses + organizes it into meaningful experiences.
• Happens unconsciously.
• The brain makes sense of the world by creating whole structures out of bits + pieces of information in the environment.
• Each whole that is organized by the brain is called a gestalt (the experience that comes from organizing bits + pieces of information into meaningful wholes).
• Principles the brain uses in constructing perceptions:
• Proximity
• Similarity
• Continuity
• Closure
• Simplicity (or symmetry)
• Diagram p.224

• Figureground perception
• Ability to discriminate b/w a figure + its background.
• The figure is whatever you are focusing on
– it can change in any given scene.
• Important b/c it shows we can see a single pattern in more than one way + aren’t just passive receivers of stimuli.
• Applies to hearing as well, such as focusing on one conversation in a crowded room or a particular part of a song.

• Perceptual inference
• We often have perceptions that aren’t based entirely on current sensory information.
• We fill in gaps based on past experience + are probably born w/ some of our ability.
• You hear a meow + assume it’s a cat.
• You see a road go up a hill + assume it doesn’t drop off at the top.
• Largely automatic + unconscious.

• Learning to perceive
• Perceiving is something that we learn to do.
• Active involvement in one’s environment is important for accurate perception.
• Learning to perceive is influenced by our needs, beliefs, + expectations.
• We are more likely to see something we want to see.
• What we identify as truth may be twisted + reconstructed to fit our own belief systems.
• Previous experiences influence what we see.
• Read p.236-7 “To See and Not See”

• Subliminal perception
• Subliminal messages are brief auditory or visual messages presented below the absolute threshold so that there is less than a 50% chance that they will be perceived.
• The idea is to get people to do something w/o being aware of why – it affects their unconscious mind only.
• Advertisers tried this in the 1950s. When the public found out there was a large outcry. Although its success was never really proven, laws were passed banning subliminal advertising.

• Ability to recognize distances + 3-dimensionality.
• Develops in infancy – tests show that infants placed on a table usually won’t crawl over the edge.
• Monocular depth cues help perceive distance + depth. They can be used w/ a single eye:
• Size (bigger is nearer)
• Relative height (objects farther away are higher on your plain of view)
• Interposition – overlapping of images
(objects we can see entirely are closer than one that is partially blocked)

• Light + shadows (brightly lit objects appear closer)
• Texture-density gradient (the farther away an object is, the less detail we see)
• Motion parallax – the apparent movement of objects that occurs when you move your head or are walking
(closer objects appear to move more)
• Linear perspective (parallel lines seem to converge in the distance)
• Relative motion – ex. When riding in a car looking at distant objects, nearby objects appear seem to be moving in the opposite direction. But when looking at nearby objects, distant objects appear to be moving in the same direction.

• Binocular depth cues depend on the movement of both eyes:
• Convergence (your eyes turn inward to look at nearby objects)
• Look at a friend's eyes as you hold your finger in front of him or her and move it towards the nose.
You will see the eyes converge.
• Retinal disparity - difference b/w the images on the retinas stimulating each eye
(A large amount of retinal disparity tells the brain the object is nearby)
• Remember: Try holding your pen or pencil in front of your face. Close your left eye + look at it only w/ your right. Now quickly close your right eye and look at it only w/ your left.
Do this several times.

• Constancy • The tendency to perceive certain objects in the same way regardless of changing angle, distance, or lighting.
• Illusions • Perceptions that misrepresent physical stimuli (incorrect perceptions).
• Created when perceptual cues are distorted, so our brains can’t correctly interpret space, size +/or depth cues.

• Extrasensory perception
(ESP)
• The ability to gain information by some means other than the ordinary senses.
• Widely debated – most scientists don’t accept it.
• 4 types:
1. Clairvoyance – perceiving objects or information w/o sensory input.
2. Telepathy – reading someone’s mind or transferring one’s thoughts.
3. Psychokinesis – moving objects through mental effort.
4. Precognition – knowing something will happen before it does.
• Why do so many people accept it?
• B/c they may have a premonition that some unlikely event will occur + it does.
They remember that event + forget all of the premonitions that never came true.
End Section 3