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198 Cards in this Set

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biological psychology
a branch of psychology concerned with the links between biology and behavior. (Some biological psychologists call themselves behavioral neuroscientists, neuropsychol- ogists, behavior geneticists, physiological psychologists, or biopsychologists.)
a nerve cell; the basic building block of the nervous system.
neurons neurons that carry incoming information from the sensory receptors to the brain and spinal cord.
motor neurons
neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.
neurons within the brain and spinal cord that communicate inter- nally and intervene between the sensory inputs and motor outputs.
the bushy, branching exten- sions of a neuron that receive messages and conduct impulses toward the cell body.
the extension of a neuron, end- ing in branching terminal fibers, through which messages pass to other neurons or to muscles or glands.
sheath a layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.
action potential
a neural impulse; a brief electrical charge that travels down an axon.
Acetylcholine (ACh)
Enables muscle action, learning, and memory. With Alzheimer’s disease, ACh-producing neurons deteriorate.
Influences movement, learning, attention, and emotion. Excess dopamine receptor activity is linked to schizophrenia. Starved of dopamine, the brain produces the tremors and decreased mobility of Parkinson’s disease.
Affects mood, hunger, sleep, and arousal. Undersupply linked to depression. Prozac and some other antidepressant drugs raise serotonin levels.
Helps control alertness and arousal. Undersupply can depress mood.
GABA (gamma-aminobutyric acid)
A major inhibitory neurotransmitter. Undersupply linked to seizures, tremors, and insomnia.
A major excitatory neuro- transmitter; involved in memory. Oversupply can overstimulate brain, producing migraines or seizures (which is why some people avoid MSG, monosodium glutamate, in food).
the level of stimulation required to trigger a neural impulse.
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.
chemical messen- gers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
a neurotransmitter’s reab- sorption by the sending neuron.
Acetylcholine (ACh)
one of the best-understood neurotransmitters. In addition to its role in learning and memory, ACh is the messenger at every junction between a motor neuron and skeletal muscle
nervous system
the body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.
central nervous system (CNS)
the brain and spinal cord.
peripheral nervous system (PNS)
the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.
bundled axons that form neural “cables” connecting the central nervous system with muscles, glands, and sense organs.
somatic nervous system
the division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skeletal nervous system.
autonomic nervous system
the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.
sympathetic nervous system
the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.
name the two parts of the peripheral nervous system (PNS)
Autonomic and Somatic
name the two parts of the autonomic nervous system
Sympathetic and Parasympathetic
parasympathetic nervous system
division of the autonomic nervous system that calms the body, conserving its energy.
a simple, automatic response to a sensory stimulus, such as the knee-jerk response.
endocrine system
the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.
chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.
adrenal glands
a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.
pituitary gland
the endocrine system’s most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.
tissue destruction. A brain lesion is a naturally or experimen- tally caused destruction of brain tissue.
electroencephalogram (EEG)
an amplified recording of the waves of electrical activity that sweep across the brain’s surface. These waves are mea- sured by electrodes placed on the scalp.
PET (positron emission tomography) scan
visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.
MRI (magnetic resonance imaging)
technique that uses magnetic fields and radio waves to produce computergenerated images of soft tissue. MRI scans show brain anatomy.
fMRI (functional MRI)
technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function.
oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions.
the base of the brainstem; controls heartbeat and breathing.
reticular formation
nerve network in the brainstem that plays an important role in controlling arousal.
the brain’s sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.
“little brain” at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance.
limbic system
neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives
two lima bean–sized neural clusters in the limbic system; linked to emotion.
a neural structure lying below (hypo) the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.
cerebral cortex
intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center.
glial cells
cells in the nervous system that SUPPORT, NOURISH, AND PROTECT NEURONS.
frontal lobes
parietal lobes
portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position.
occipital lobes
portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields.
temporal lobes
portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear.
motor cortex
an area at the rear of the frontal lobes that controls voluntary movements.
sensory cortex
area at the front of the parietal lobes that registers and processes body touch and movement sensations.
association areas
areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.
brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.
What are neurons, and how do they transmit information?
Neurons are the elementary components of the nervous sys- tem, the body’s speedy electrochemical information system. Sensory neurons carry incoming information from sense re- ceptors to the brain and spinal cord, and motor neurons carry information from the brain and spinal cord out to the mus- cles and glands. Interneurons communicate within the brain and spinal cord and between sensory and motor neurons. A neuron sends signals through its axons, and receives signals through its branching dendrites. If the combined signals are strong enough, the neuron fires, transmitting an electrical impulse (the action potential) down its axon by means of a chemistry-to-electricity process. The neuron’s reaction is an all-or-none process.
How do nerve cells communicate with other nerve cells?
When action potentials reach the end of an axon (the axon terminals), they stimulate the release of neurotransmitters. These chemical messengers carry a message from the sending neuron across a synapse to receptor sites on a receiving neu- ron. The sending neuron, in a process called reuptake, then normally absorbs the excess neurotransmitter molecules in the synaptic gap. The receiving neuron, if the signals from that neuron and others are strong enough, generates its own action potential and relays the message to other cells
How do neurotransmitters influence behavior, and how do drugs and other chemicals affect neurotransmission?
Each neurotransmitter travels a designated path in the brain and has a particular effect on behavior and emotions. Acetyl- choline affects muscle action, learning, and memory. Endor- phins are natural opiates released in response to pain and exercise. Drugs and other chemicals affect communication at the synapse. Agonists excite by mimicking particular neuro- transmitters or by blocking their reuptake. Antagonists inhibit a particular neurotransmitter’s release or block its effect.
What are the functions of the nervous system’s main divisions?
One major division of the nervous system is the central nervous system (CNS), the brain and spinal cord. The other is the pe- ripheral nervous system (PNS), which connects the CNS to the rest of the body by means of nerves. The peripheral nervous system has two main divisions. The somatic nervous system en- ables voluntary control of the skeletal muscles. The autonomic nervous system, through its sympathetic and parasympathetic divisions, controls involuntary muscles and glands. Neurons cluster into working networks.
How does the endocrine system—the body’s slower information system—transmit its messages?
The endocrine system is a set of glands that secrete hormones into the bloodstream, where they travel through the body and affect other tissues, including the brain. The endocrine sys- tem’s master gland, the pituitary, influences hormone release by other glands. In an intricate feedback system, the brain’s hypothalamus influences the pituitary gland, which influences other glands, which release hormones, which in turn influ- ence the brain.
How do neuroscientists study the brain’s connections to behavior and mind?
Clinical observations and lesioning reveal the general effects of brain damage. MRI scans now reveal brain structures, and EEG, PET, and fMRI (functional MRI) recordings reveal brain activity.
What are the functions of important lower-level brain structures?
The brainstem is the oldest part of the brain and is responsible for automatic survival functions. Its components are the medulla (which controls heartbeat and breathing), the pons (which helps coordinate movements), and the reticular forma- tion (which affects arousal). The thalamus, the brain’s sensory switchboard, sits above the brainstem. The cerebellum, at- tached to the rear of the brainstem, coordinates muscle move- ment and helps process sensory information.
The limbic system is linked to emotions, memory, and dri- ves. Its neural centers include the amygdala (involved in re- sponses of aggression and fear) and the hypothalamus (involved in various bodily maintenance functions, pleasur- able rewards, and the control of the hormonal system). The pituitary (the “master gland”) controls the hypothalamus by stimulating it to trigger the release of hormones. The hip- pocampus processes memory.
What functions are served by the various cerebral cortex regions?
In each hemisphere the cerebral cortex has four lobes, the frontal, parietal, occipital, and temporal. Each lobe performs many functions and interacts with other areas of the cortex. The motor cortex controls voluntary movements. The sensory cortex registers and processes body sensations. Body parts re- quiring precise control (in the motor cortex) or those that are especially sensitive (in the sensory cortex) occupy the greatest amount of space. Most of the brain’s cortex—the major portion of each of the four lobes—is devoted to uncommitted associa- tion areas, which integrate information involved in learning, remembering, thinking, and other higher-level functions.
To what extent can a damaged brain reorganize itself?
If one hemisphere is damaged early in life, the other will pick up many of its functions. This plasticity diminishes later in life. Some brain areas are capable of neurogenesis (forming new neurons).
What do split brains reveal about the functions of our two brain hemispheres?
Split-brain research (experiments on people with a severed cor- pus callosum) has confirmed that in most people, the left hemisphere is the more verbal, and that the right hemisphere excels in visual perception and the recognition of emotion. Studies of healthy people with intact brains confirm that each hemisphere makes unique contributions to the integrated functioning of the brain.
How does handedness relate to brain organization?
About 10 percent of us are left-handed. Almost all right- handers process speech in the left hemisphere, as do more than half of all left-handers.
the formation of new neurons
corpus callosum
large band of neural fibers connecting the two brain hemispheres and carrying messages between them.
split brain
condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them.
behavior genetics
study of the relative power and limits of genetic and environmental influences on behavior.
every nongenetic influence, from prenatal nutrition to the people and things around us.
threadlike structures made of DNA molecules that contain the genes.
complex molecule containing the genetic information that makes up the chromosomes.
biochemical units of heredity that make up the chromosomes; a segment of DNA capable of synthesizing a protein.
complete instructions for making an organism, consisting of all the genetic material in that organism’s chromosomes.
identical twins
twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms.
fraternal twins
twins who develop from separate fertilized eggs. They are genetically no closer than brothers and sisters, but they share a fetal environment.
person’s characteristic emotional reactivity and intensity.
proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied.
interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).
molecular genetics
subfield of biology that studies the molecular structure and function of genes.
evolutionary psychology
the study of the evolution of behavior and the mind, using principles of natural selection.
natural selection
principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations.
random error in gene replication that leads to a change.
in psychology, the biologically and socially influenced characteristics by which people define male and female.
enduring behaviors, ideas, attitudes, values, and traditions shared by a group of people and transmitted from one generation to the next.
an understood rule for accepted and expected behavior. Norms prescribe “proper” behavior.
personal space
buffer zone we like to maintain around our bodies.
giving priority to one’s own goals over group goals and defining one’s identity in terms of personal attributes rather than group identifications.
giving priority to goals of one’s group (often one’s extended family or work group) and defining one’s identity accordingly.
physical or verbal behavior intended to hurt someone.
X chromosome
sex chromosome found in both men and women. Females have two X chromosomes; males have one. An X chromosome from each parent produces a female child.
Y chromosome
sex chromosome found only in males. When paired with an X chromosome from the mother, it produces a male child.
most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty.
set of expectations (norms) about a social position, defining how those in the position ought to behave.
gender role
set of expected behaviors for males or for females.
gender identity
our sense of being male or female.
gender typing
acquisition of a traditional masculine or feminine role.
social learning theory
theory that we learn social behavior by observing and imitating and by being rewarded or punished.
1: What are genes, and how do behavior geneticists explain our individual differences?
Chromosomes are coils of DNA containing gene segments that, when “turned on” (expressed), code for the proteins that form our body’s building blocks. Most human traits are influenced by many genes acting together. Behavior geneticists seek to quantify genetic and environmental influences on our traits. Studies of identical twins, fraternal twins, and adoptive families help specify the influence of genetic nature and of environ- mental nurture, and the interaction between them (meaning that the effect of each depends on the other). The stability of temperament suggests a genetic predisposition.
2: What is heritability, and how does it relate to individuals and groups?
Heritability describes the extent to which variation among members of a group can be attributed to genes. Heritable individual differences in traits such as height or intelligence need not explain group differences. Genes mostly explain why some are taller than others, but not why people today are taller than a century ago.
3: What is the promise of molecular genetics research?
Molecular geneticists study the molecular structure and function of genes. Psychologists and molecular geneticists are co- operating to identify specific genes—or more often, teams of genes—that put people at risk for disorders.
4: How do evolutionary psychologists use natural selection to explain behavior tendencies?
Evolutionary psychologists seek to understand how natural selection has shaped our traits and behavior tendencies. The principle of natural selection states that variations increasing the odds of reproducing and surviving are most likely to be passed on to future generations. Some variations arise from mutations (random errors in gene replication), others from new gene combinations at conception. Charles Darwin, whose theory of evolution has for a long time been an organizing principle in biology, anticipated the contemporary application of evolutionary principles in psychology.
5: How might an evolutionary psychologist explain gender differences in mating preferences?
Men more than women approve of casual sex, think about sex, and misinterpret friendliness as sexual interest. Women more than men cite affection as a reason for first intercourse and have a relational view of sexual activity. Applying principles of natural selection, evolutionary psychologists reason that men’s attraction to multiple healthy, fertile-appearing partners increases their chances of spreading their genes widely. Because women incubate and nurse babies, they in- crease their own and their children’s chances of survival by searching for mates with the resources and the potential for long-term investment in their joint offspring.
6: What are the key criticisms of evolutionary psychology?
Critics argue that evolutionary psychologists start with an effect and work backward to an explanation, that the evolutionary perspective gives too little emphasis to social influences, and that the evolutionary viewpoint absolves people from taking responsibility for their sexual behavior. Evolutionary psychologists respond that understanding our predispositions can help us overcome them. They also cite the value of testable predictions based on evolutionary principles, as well as the coherence and explanatory power of those principles.
7: To what extent are our lives shaped by early stimulation, by parents, and by peers?
During maturation, a child’s brain changes as neural connections increase in areas associated with stimulating activity, and unused synapses degenerate. Parents influence their children in areas such as manners and political and religious beliefs, but not in other areas, such as personality. Language and other behaviors are shaped by peer groups, as children adjust to fit in. By choosing their children’s neighborhoods and schools, parents can exert some influence over peer group culture.
8: How do cultural norms affect our behavior?
Cultural norms are rules for accepted and expected behaviors, ideas, attitudes, and values. Across places and over time cultures differ in their norms. Despite such cultural variations, we humans share many common forces that influence behavior.
9: How do individualist and collectivist cultural influences affect people?
Cultures based on self-reliant individualism, like those of most of the United States, Canada, Australia, and Western Europe, value personal independence and individual achievement. Identity is defined in terms of self-esteem, personal goals and attributes, and personal rights and liberties. Cultures based on socially connected collectivism, like those of many parts of Asia and Africa, value interdependence, tradition, and harmony, and they define identity in terms of group goals and commitments and belonging to one’s group. Within any culture, the degree of individualism or collectivism varies from person to person.
10: What are some ways in which males and females tend to be alike and to differ?
Human males and females are more alike than different, thanks to their similar genetic makeup. Regardless of our gender, we see, hear, learn, and remember similarly. Males and females do differ in body fat, muscle, height, age of onset of puberty, and life expectancy; in vulnerability to certain disorders; and in aggression, social power, and social connectedness.
11: How do nature and nurture together form our gender?
Biological sex is determined by the twenty-third pair of chromosomes, to which the mother contributes an X chromosome and the father either an X (producing a female) or a Y chromosome (producing a male). A Y chromosome triggers additional testosterone release and male sex organs. Gender refers to the characteristics, whether biologically or socially influenced, by which people define male and female. Sex-related genes and hormones influence gender differences in behavior, possibly by influencing brain development. We also learn gender roles, which vary with culture, across place and time. Social learning theory proposes that we learn gender identity as we learn other things—through reinforcement, punishment, and observation.
process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.
process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.
bottom-up processing
analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information.
top-down processing
information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.
study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them.
absolute threshold
minimum stimulation needed to detect a particular stimulus 50 percent of the time.
signal detection theory
theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and level of fatigue.
below one’s absolute threshold for conscious awareness.
activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response.
difference threshold
minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference (or jnd).
Weber’s law
principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount).
sensory adaptation
diminished sensitivity as a consequence of constant stimulation.
conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret.
distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission.
dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth.
amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave’s amplitude.
adjustable opening in the center of the eye through which light enters.
ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening.
transparent structure behind the pupil that changes shape to help focus images on the retina.
light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.
process by which the eye’s lens changes shape to focus near or far objects on the retina.
retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don’t respond.
cones retinal receptor
cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations.
optic nerve
nerve that carries neural impulses from the eye to the brain.
blind spot
point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there.
central focal point in the retina, around which the eye’s cones cluster.
feature detectors
nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.
parallel processing
processing of many aspects of a problem simultaneously; the brain’s natural mode of information processing for many functions, including vision. Contrasts with the stepby-step (serial) processing of most computers and of conscious problem solving.
Young-Helmholtz trichromatic (three-color) theory
theory that the retina contains three different color receptors—one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any color.
opponent-process theory
theory that opposing retinal processes (redgreen, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green.
number of complete wavelengths that pass a point in a given time (for example, per second).
tone’s experienced highness or lowness; depends on frequency.
middle ear
chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window.
coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses.
inner ear
innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.
place theory
in hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated.
frequency theory
in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch
conduction hearing loss
hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.
sensorineural hearing loss
hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerves; also called nerve deafness.
cochlear implant
device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.
system for sensing the position and movement of individual body parts.
vestibular sense
sense of body movement and position, including the sense of balance.
gate-control theory
theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain. The “gate” is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain.
sensory interaction
the principle that one sense may influence another, as when the smell of food influences its taste.
an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.
the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).
the perceptual tendency to organize stimuli into coherent groups.
depth perception
the ability to see objects in three dimensions although the images that strike the retina are twodimensional; allows us to judge distance.
visual cliff
a laboratory device for testing depth perception in infants and young animals.
binocular cues
depth cues, such as retinal disparity, that depend on the use of two eyes.
retinal disparity
a binocular cue for perceiving depth: By comparing images from the retinas in the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.
monocular cues
depth cues, such as interposition and linear perspective, available to either eye alone.
phi phenomenon
an illusion of movement created when two or more adjacent lights blink on and off in quick succession.
perceptual constancy
perceiving objects as unchanging (having consistent shapes, size, lightness, and color) even as illumination and retinal images change.
color constancy
perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object.
perceptual adaptation
in vision, the ability to adjust to an artificially displaced or even inverted visual field.
perceptual set
a mental predisposition to perceive one thing and not another.
human factors psychology
a branch of psychology that explores how people and machines interact and how machines and physical environments can be made safe and easy to use.
extrasensory perception (ESP)
the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition.
the study of paranormal phenomena, including ESP and psychokinesis.
1: What are sensation and perception? What do we mean by bottom-up processing and top-down processing?
Sensation is the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment. Perception is the process of organizing and interpreting this information. Although we view sensation and perception separately to analyze and discuss them, they are actually parts of one continuous process. Bottom-up processing is sensory analysis that begins at the entry level, with information flowing from the sensory receptors to the brain. Top-down processing is analysis that begins with the brain and flows down, filtering information through our experience and expectations to produce perceptions.
2: What are the absolute and difference thresholds, and do stimuli below the absolute threshold have any influence?
Our absolute threshold for any stimulus is the minimum stimulation necessary for us to be consciously aware of it 50 percent of the time. Signal detection theory demonstrates that individual absolute thresholds vary, depending on the strength of the signal and also on our experience, expectations, motivation, and alertness. Our difference threshold (also called just noticeable difference, or jnd) is the barely noticeable difference we discern between two stimuli 50 percent of the time. Priming shows that we can process some information from stimuli below our absolute threshold for conscious awareness. But the effect is too fleeting to enable people to exploit us with subliminal messages. Weber’s law states that two stimuli must differ by a constant proportion to be perceived as different.
3: What is the function of sensory adaptation?
Sensory adaptation (our diminished sensitivity to constant or routine odors, sounds, and touches) focuses our attention on informative changes in our environment.
4: What is the energy that we see as visible light?
Each sense receives stimulation, transforms (transduces) it into neural signals, and sends these neural messages to the brain. In vision, the signals consist of light-energy particles from a thin slice of the broad spectrum of electromagnetic radiation. The hue we perceive in a light depends on its wavelength, and its brightness depends on its intensity.
5: How does the eye transform light energy into neural messages?
After entering the eye and being focused by a lens, lightenergy particles strike the eye’s inner surface, the retina. The retina’s light-sensitive rods and color-sensitive cones convert the light energy into neural impulses which, after processing by bipolar and ganglion cells, travel through the optic nerve to the brain.
6: How does the brain process visual information?
Impulses travel along the optic nerve, to the thalamus, and on to the visual cortex. In the visual cortex, feature detectors respond to specific features of the visual stimulus. Higher-level supercells integrate this pool of data for processing in other cortical areas. Parallel processing in the brain handles many aspects of a problem simultaneously, and separate neural teams work on visual subtasks (color, movement, depth, and form). Other neural teams integrate the results, comparing them with stored information, and enabling perceptions.
7: What theories help us understand color vision?
The Young-Helmholtz trichromatic (three-color) theory proposed that the retina contains three types of color receptors. Contemporary research has found three types of cones, each most sensitive to the wavelengths of one of the three primary colors of light (red, green, or blue). Hering’s opponent-process theory proposed three additional color processes (red-versus-green, blue-versus-yellow, black-versus-white). Contemporary research has confirmed that, en route to the brain, neurons in the retina and the thalamus code the color-related information from the cones into pairs of opponent colors. These two theories, and the research supporting them, show that color processing occurs in two stages.
8: What are the characteristics of air pressure waves that we hear as sound?
Sound waves are bands of compressed and expanded air. Our ears detect these changes in air pressure and transform them into neural impulses, which the brain decodes as sound. Sound waves vary in frequency, which we experience as differing pitch, and amplitude, which we perceive as differing loudness.
9: How does the ear transform sound energy into neural messages?
The outer ear is the visible portion of the ear. The middle ear is the chamber between the eardrum and cochlea. The inner ear consists of the cochlea, semicircular canals, and vestibular sacs. Through a mechanical chain of events, sound waves traveling through the auditory canal cause tiny vibrations in the eardrum. The bones of the middle ear amplify the vibrations and relay them to the fluid-filled cochlea. Rippling of the basilar membrane, caused by pressure changes in the cochlear fluid, causes movement of the tiny hair cells, triggering neural messages to be sent (via the thalamus) to the auditory cortex in the brain.
10: What theories help us understand pitch perception?
Place theory proposes that our brain interprets a particular pitch by decoding the place where a sound wave stimulates the cochlea’s basilar membrane. Frequency theory proposes that the brain deciphers the frequency of the pulses traveling to the brain. Place theory explains how we hear high-pitched sounds, but it cannot explain how we hear low-pitched sounds. Frequency theory explains how we hear low-pitched sounds, but it cannot explain how we hear high-pitched sounds. Some combination of the two helps explain how we hear sounds in the middle range.
11: How do we locate sounds?
Sound waves strike one ear sooner and more intensely than the other. The brain analyzes the minute differences in the sounds received by the two ears and computes the sound’s source.
12: What are the common causes of hearing loss, and why does controversy surround cochlear implants?
Conduction hearing loss results from damage to the mechanical system that transmits sound waves to the cochlea. Sensorineural hearing loss (or nerve deafness) results from damage to the cochlea’s hair cells or their associated nerves. Diseases and accidents can cause hearing loss, but age-related disorders and prolonged exposure to loud noises are more common causes. Artificial cochlear implants can restore hearing for some people, but members of the Deaf culture movement believe cochlear implants are unnecessary for people who have been Deaf from birth and who can speak their own language, sign.
13: How do we sense touch and sense our body’s position and movement?
How do we experience pain? Our sense of touch is actually several senses—pressure, warmth, cold, and pain—that combine to produce other sensations, such as “hot.” Through kinesthesis, we sense the position and movement of body parts. We monitor the body’s position and maintain our balance with our vestibular sense. Pain is an alarm system that draws our attention to some physical problem. One theory of pain is that a “gate” in the spinal cord either opens to permit pain signals traveling up small nerve fibers to reach the brain, or closes to prevent their passage. The biopsychosocial approach views pain as the sum of three sets of forces: biological influences, such as nerve fibers sending messages to the brain; psychological influences, such as our expectations; and social-cultural influences, such as the presence of others. Treatments to control pain often combine physiological and psychological elements.
14: How do we experience taste?
Taste, a chemical sense, is a composite of five basic sensations—sweet, sour, salty, bitter, and umami—and of the aromas that interact with information from the taste receptor cells of the taste buds. The influence of smell on our sense of taste is an example of sensory interaction, the ability of one sense to influence another.
15: How do we experience smell?
There are no basic sensations for smell. Smell is a chemical sense. Some 5 million olfactory receptor cells, with their approximately 350 different receptor proteins, recognize individual odor molecules. The receptor cells send messages to the brain’s olfactory bulb, then to the temporal lobe and to parts of the limbic system. Odors can spontaneously evoke memories and feelings, due in part to the close connections between brain areas that process smell and memory.
16: How did the Gestalt psychologists understand perceptual organization?
Gestalt psychologists searched for rules by which the brain organizes fragments of sensory data into gestalts (from the German word for “whole”), or meaningful forms. In pointing out that the whole is more than the sum of its parts, they noted that we filter sensory information and infer perceptions in ways that make sense to us.
17: How do figure-ground and grouping principles contribute to our perceptions?
To recognize an object, we must first perceive it (see it as a figure) as distinct from its surroundings (the ground). We bring order and form to stimuli by organizing them into meaningful groups, following the rules of proximity, similarity, continuity, connectedness, and closure.
18: How do we see the world in three dimensions?
Depth perception is our ability to see objects in three dimensions and judge distance. The visual cliff and other research demonstrates that many species perceive the world in three dimensions at, or very soon after, birth. Binocular cues, such as retinal disparity, are depth cues that rely on information from both eyes. Monocular cues (such as relative size, interposition, relative height, relative motion, linear perspective, and light and shadow) let us judge depth using information transmitted by only one eye.
19: How do we perceive motion?
As objects move, we assume that shrinking objects are retreating and enlarging objects are approaching. But sometimes we miscalculate. A quick succession of images on the retina can create an illusion of movement, as in stroboscopic movement or the phi phenomenon.
20: How do perceptual constancies help us organize our sensations into meaningful perceptions?
Perceptual constancy enables us to perceive objects as stable despite the changing image they cast on our retinas. Shape constancy is our ability to perceive familiar objects (such as an opening door) as unchanging in shape. Size constancy is perceiving objects as unchanging in size despite their changing retinal images. Knowing an object’s size gives us clues to its distance; knowing its distance gives clues about its size, but we sometimes misread monocular distance cues and reach the wrong conclusions, as in the Moon illusion. Lightness (or brightness) constancy is our ability to perceive an object as having a constant lightness even when its illumination—the light cast upon it—changes. The brain perceives lightness relative to surrounding objects. Color constancy is our ability to perceive consistent color in objects, even though the lighting and wavelengths shift. Our brain constructs our experience of the color of an object through comparisons with other surrounding objects.
21: What does research on sensory restriction and restored vision reveal about the effects of experience?
People who were born blind but regained sight after surgery lack the experience to recognize shapes, forms, and complete faces. Animals who have had severely restricted visual input suffer enduring visual handicaps when their visual exposure is returned to normal. There is a critical period for some aspects of sensory and perceptual development. Without early stimulation, the brain’s neural organization does not develop normally.
22: How adaptable is our ability to perceive?
Perceptual adaptation is evident when people are given glasses that shift the world slightly to the left or right, or even upsidedown. People are initially disoriented, but they manage to adapt to their new context.
23: How do our expectations, contexts, and emotions influence our perceptions?
Perceptual set is a mental predisposition that functions as a lens through which we perceive the world. Our learned concepts (schemas) prime us to organize and interpret ambiguous stimuli in certain ways. The surrounding context helps create expectations that guide our perceptions. Emotional context can color our interpretation of other people’s behaviors, as well as our own.
24: How do human factors psychologists work to create user-friendly machines and work settings?
Human factors psychologists contribute to human safety and improved design by encouraging developers and designers to consider human perceptual abilities, to avoid the curse of knowledge, and to test users to reveal perception-based problems.
25: What are the claims of ESP, and what have most research psychologists concluded after putting these claims to the test?
The three most testable forms of extrasensory perception (ESP) are telepathy (mind-to-mind communication), clairvoyance (perceiving remote events), and precognition (perceiving future events). Most research psychologists’ skepticism focuses on two points. First, to believe in ESP, you must believe the brain is capable of perceiving without sensory input. Second, psychologists and parapsychologists have been unable to replicate (reproduce) ESP phenomena under controlled conditions.