psych midterm

our awareness of ourselves and our environment.

the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language).

the principle that information is often simultaneously processed on separate conscious and unconscious tracks.

the focusing of conscious awareness on a particular stimulus.

failing to notice changes in the enviornment.

the biological clock; regular body rhythms (for example, of temperature and wakefulness) that occur on a 24 hour cycle.

rapid eye movement sleep, a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for most minor twitches) but other body systems are active.

the relatively slow brain waves of a relaxed, awake state.

periodic, natural, reversible loss of consciousness--as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation

false sensory experiences, such as seeing something in the absence of an external visual stimulus.

the large, slow brain waves associated with deep sleep.

recurring problem in falling or staying asleep.

a sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, often at inopportune times.

a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.

a sleep disorder characterized by high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during Stage 4 sleep, within two or three hours of falling asleep, and are seldom remembered.

a sequence of images, emotions, and thoughts passing through a sleeping person's mind. Dreams are notable for their hallucinatory imagery, discontinuities, and incongruities, and for the dreamer's delusional acceptance of the content and later difficulties remembering it.

according to Freud, the remembered story line of a dream (as distinct from its latent, or hidden, content).

according to Freud, the underlying meaning of a dream (as distinct from its manifest content).

failing to see visible objects when our attention is directed elsewhere.

the tendency for REM sleep to increase following REM sleep deprivation (created by repeated awakenings during REM sleep).

a social interaction in which one person (the hypnotist) suggests to another (the subject) that certain perceptions, feelings, thoughts, or behaviors will spontaneously occur.

a suggestion, made during a hypnosis session, to be carried out after the subject is no longer hypnotized; used by some clinicians to help control undesired symptoms and behaviors.

a split in the consciousness, which allows some thoughts and behaviors to occur simultaneously with others.

a chemical substance that alters perceptions and moods.

the diminishing effect with regular use of the same does of a drug, requiring the user to take larger and larger doses before experiencing the drug's effect.

the discomfort and distress that follow discontinuing the use of an addictive drug.

a physiological need for a drug, marked by unpleasant withdrawal symptoms when the drug is discontinued.

a psychological need to use a drug, such as to relieve negative emotions.

compulsive drug craving and use, despite adverse consequences.

drugs (such as alcohol, barbiturates, and opiates) that reduce neural activity and slow body functions.

drugs that depress the activity of the central nervous system, reducing anxiety but impairing memory and judgment.

opium and its derivatives, such as morphine and heroin; they depress neural activity, temporarily lessening pain and anxiety.

drugs (such as caffeine, nicotine, and the more powerful amphetamines, cocaine, and Ecstasy) that excite neural activity and speed up body functions.

drugs that stimulate neural activity, causing speeded-up body functions and associated energy and mood changes.

a powerfully addictive drug that stimulates the central nervous system, with speeded-up body functions and associated energy and mood changes; over time, appears to reduce baseline dopamine levels.

a synthetic stimulant and mild hallucinogen. Produces euphoria and social intimacy, but with short-term health risks and longer-term harm to serotonin-producing neurons and to mood and cognition.

psychedelic ("mind-manifesting") drugs, such as LSD, that distort perceptions and evoke sensory images in the absence of sensory input.

a powerful hallucinogenic drug; also known as acid (lysergic acid diethylamide).

the major active ingredient in marijuana; triggers a variety of effects, including mild hallucinations.

an altered state of consciousness reported after a close brush with death (such as through cardiac arrest); often similar to drug-induced hallucinations.

the 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.

a complex molecule containing the genetic information that makes up the chromosomes.

the biochemical units of heredity that make up the chromosomes; a segment of DNA capable of synthesizing a protein.

the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes.

twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms.

twins who develop from separate fertilized eggs. They are genetically no closer than brothers and sisters, but they share a fetal environment.

a person's characteristic emotional reactivity and intensity

The 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.

the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).

the subfield of biology that studies the molecular structure and function of genes.

the study of the evolution of behavior and the mind, using principles of natural selection.

the 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.

a 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.

The 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. prescribe "proper" behavior.

the 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 the 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.

the sex chromosome found in both men and women. Females have two; males have one. An X chromosome from each parent produces a female child.

the sex chromosome found only in males. When paired with an X chromosome from the mother, it produces a male child.

the 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.

a set of expectations (norms) about a social position, defining how those in the position ought to behave

a set of expected behaviors for males and for females.

The acquisition of a traditional masculine or feminine role.

the theory that we learn social behavior by observing and imitating and by being rewarded or punished.

a relatively permanent change in an organism's behavior due to experience

learning that certain events occur together. The events may be two stimuli (as in classical conditioning) or a response and its consequences (as in operant conditioning)

a type of learning in which an organism comes to associate stimuli. A neutral stimulus that signals an unconditioned stimulus (US) begins to produce a response to anticipates and prepares for the unconditioned stimulus. Also called Pavlovian or respondent conditioning.

in classical conditioning, the unlearned naturally occurring response to the unconditioned stimulus (US), such as salivation when food is in the mouth.

in classical conditioning, a stimulus that unconditionally-naturally and automatically-triggers a response.

in classical conditioning, the learned response to a previously neutral (but now conditioned) stimulus

in classical conditioning, an originally irrelevant stimulus that, after association with an unconditioned stimulus (US), comes to trigger a conditioned response.

the initial stage in classical conditioning; the phase associating a neutral stimulus with an unconditioned stimulus so that the neutral stimulus comes to elicit a conditioned response. In operant conditioning, the strengthening of a reinforced response.

the diminishing of a conditioned response; occurs in classical conditioning when an unconditioned stimulus (US) does not follow a conditioned stimulus (CS); occurs in operant conditioning when a response is no longer reinforced

the reappearance after a pause, of an extinguished conditioned response

the tendency, once a response has been conditioned, for stimuli similar to the conditioned stimulus to elicit similar responses.

in classical conditioning, the learned ability to distinguish between a conditioned stimulus and stimuli that do not signal an unconditioned stimulus

behavior that occurs as an automatic response to some stimuli

a type of leaning in which behavior is strengthened if followed by a reinforcer or diminished if followed by punishment

behavior that operates on the environment, producing consequences.

a chamber also known as a skinner box, containing a bar or key that an animal can manipulate to obtain a food or water reinforcer, with attached devices to record the animal's rate of bar pressing or key pecking. Used in operant conditioning research.

an operant conditioning procedure in which reinforcers guide behavior toward closer approximations of the desired behavior.

in operant conditioning, any event that strengthens the behavior.

increasing behaviors by presenting positive stimuli, such as food. A positive reinforcer is any stimulus that, when presented after a response, strengthens the response.

increasing behaviors by stopping or reducing negative stimuli, such as shock. A negative reinforcer is any stimulus that, when removed after a response, strengthens the response. (Note: negative reinforcement is not punishment)

an innately reinforcing stimulus, such as one that satisfies a biological need.

a stimulus that gains its reinforcing power through its association with a primary reinforcer; also known as secondary reinforcer.

reinforcing the desired response every time it occurs.

reinforcing a response only part of the time; results in slower acquisition of a response but much greater resistance to extinction than does continuous reinforcement.

in operant conditioning, a reinforcement schedule that reinforces a response only after a specified number of responses.

in operant conditioning, a reinforcement schedule that reinforces a response after an unpredictable number of response.

in operant conditioning, a reinforcement schedule that reinforces a response only after a specified time has elapsed.

in operant conditioning, a reinforcement schedule that reinforces a response at unpredictable time intervals.

an event that decreases the behavior it follows.

a mental representation of the layout of one's environment. For example, after exploring a maze, rats act as if they have learned a cognitive map of it.

learning that occurs, but is not apparent until there is an incentive to demonstrate it.

a desire to perform a behavior for its own sake

a desire to perform a behavior due to promised rewards or threats of punishment.

learning by observing others

the process of observing and imitating a specific behavior.

frontal lobe neurons that fire when performing certain actions or when observing another doing so. The brain's mirroring of another's action may enable imitation and empathy

a need or desire that energizes and directs behavior.

a complex behavior that is rigidly patterned throughout a species and is unlearned.

the idea that a physiological need creates an aroused tension state (a drive) that motivates an organism to satisfy the need.

a tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level.

a positive or negative environmental stimulus that motivates behavior.

Maslow's pyramid of human needs, beginning at the base with physiological needs that must first be satisfied before higher-level safety needs and then psychological needs become active.

the form of sugar that circulates in the blood and provides the major source of energy for body tissues. When its level is low, we feel hunger.

the point at which an individual's "weight thermostat" is supposedly set. When the body falls below this weight, an increase in hunger and a lowered metabolic rate may act to restore the lost weight.

the body's resting rate of energy expenditure

an eating disorder in which a person (usually an adolescent female) diets and becomes significantly (15 percent or more) underweight, yet, still feeling fat, continues to starve.

an eating disorder characterized by episodes of overeating, usually of high-calorie foods, followed by vomiting, laxative use, fasting, or excessive exercise.

significant binge-eating episodes, followed by distress, disgust, or guilt, but without the compensatory purging, fasting, or excessive exercise that marks bulimia nervosa.

the four stages of sexual responding described by Masters and Johnson-excitement, plateau, orgasm, and resolution.

a resting period after orgasm, during which a man cannot achieve another orgasm.

a problem that consistently impairs sexual arousal or functioning.

sex hormones, such as estradiol, secreted in greater amounts by females than by males and contributing to female sex characteristics. In nonhuman female mammals, estrogen levels peak during ovulation, promoting sexual receptivity.

the 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.

an enduring sexual attraction toward members of either one's own sex (homosexual orientation) or the other sex (heterosexual orientation).

a completely involved, focused state of consciousness, with diminished awareness of self and time, resulting from optimal engagement of one's skills.

the application of psychological concepts and methods to optimizing human behavior in workplaces.

a subfield of I/O psychology that focuses on employee recruitment, selection, placement, training, appraisal, and development.

a subfield of I/O psychology that examines organizational influences on worker satisfaction and productivity and facilitates organizational change.

interview process that asks the same job relevant questions of all applicants, each of whom is rated on established scales.

a desire for significant accomplishment; for mastery of things, people, or ideas; for rapidly attaining a high standard.

goal-oriented leadership that sets standards, organizes work, and focuses attention on goals.

group-oriented leadership that builds teamwork, mediates conflict, and offers support.

the view that psychology should be an objective science and studies behavior without reference to mental processes.

Memory aids, especially those techniques that use vivid imagery and organizational devices

The tendency to believe, after learning an outcome, that ones would have foreseen it. (Also known as the I-knew-it-all-along phenomenon)

Thinking that does not blindly accept arguments and conclusions. Rather, it examines assumptions, discerns hidden values, evaluates evidence, and assesses conclusions.

An explanation using an integrated set of principles that organizes observations and predicts behaviors or events.

A testable prediction, often implied by a theory.

A statement of the procedures (operations) used to define research variables.

Repeating the essence of a research study, usually with different participants in different situations, so see whether the basic finding extends to other participants and circumstances.

An observation technique in which one person is studied in depth in the hope of revealing universal principles.

A technique for ascertaining the self-reported attitudes or behaviors of people, usually by questioning a representative, random sample of them.

The tendency to overestimate the extent to which others share our beliefs and behaviors.

All the cases in a group, from which samples may be drawn for a study.

A sample that fairly represents a population because each member has an equal chance of inclusion.

Observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation.

A measure of the extent to which two factors vary together, and this of how well either factor predicts the other.

A graphed cluster of dots, each of which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation.

The perception of a relationship where none exists.

A research method in which an investigator manipulates one of more factors to observe the effect on some behavior or mental process.

An experimental procedure in which both the research participants and the research staff are ignorant about whether the research participants have received the treatment or the placebo.

Experimental results caused by expectations alone.

The condition of an experiment that exposes participants to the treatment, that is, to one version of the independent variable.

The condition of an experiment that contrasts with the experimental condition and serves as a comparison for evaluating the effect of the treatment.

Assigning participants to experimental and control conditions by chance.

The experimental factor that is manipulated; the variable whose effect is being studied.

The outcome factor; the variable that may change in response to manipulations of the independent variable.

The most frequently occurring score(s) in a distribution.

The arithmetic average of a distribution.

The middle score in a distribution; half the scores are above it and half are below it.

The difference between the highest and lowest scores in a distribution.

A computed measure of how much scores vary around the mean score.

A statistical statement of how likely it is that an obtained result occurred by chance.

The enduring behaviors, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next.

a branch of psychology concerned with the links between biology and behavior.

a nerve cell; the basic building block of of the nervous system.

the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body

the extension of a neuron ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands.

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.

a neural impulse; a brief electrical charge that travels down an axon. The action potential is generated by the movement of positively charged atoms in and out of channels in the axon's membrane.

the level of stimulation required to trigger a neural jmpulse

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving the neuron.

the tiny gap at this junction (synapse)

chemical messengers that traverse the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sistes on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

a neurotransmitter that, among its functions, triggers muscle contraction.

"morphine within" - natural, opiatelike neurotransmitters linked to pain control and to pleasure.

the body's speedy, electrochemical communication system, consisting of all the nerve cells of the peripheral and central nervous systems.

the brain and spinal cord

the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

neural "cables" containing many axons. These bundled axons, which are part of the peripheral nervous system (PNS), connect the central nervous system (CNS) with muscles, glands, and sense organs.

neurons that carry incoming information from the sense receptors to the central nervous system (CNS).

central nervous system (CNS) neurons that internally communicate and intervene between the sensory inputs and motor inputs.

neurons that carry outgoing information from the central nervous system (CNS) to the muscles and glands.

the division of the peripheral nervous system (PNS) that controls the body's skeletal muscles.

the part of the peripheral nervous system (PNS) that controls the glands and the muscles of the internal organs (like the hear). Its sympathetics division arouses; its parasympathetic division calms.

the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.

the division of the autonomic nervous system that calms the body, conserving its energy.

a simple, automatic, inborn response to a sensory stimulus, such as the knee-jerk response.

interconnected neural cells. With experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results. Computer simulations of neural networks show analogous learning.

the process where excess neurotransmitters are reabsorbed by the sending neuron.

a poison from South American Indians put on the tips of their hunting darts, which occupies and blocks ACh receptor sites, leaving the neurotransmitter unable to affect the muscles.

poison which can possibly be formed from improperly canned food causes paralysis by blocking ACh release from the sending neuron.

function: influences movement, learning, attention, and emotion ; malfunctions: undersupply is linked to Alzheimer's disease.

function: affects mood, hunger, sleep, and arousal ; malfunctions: undersupply linked to depression. Prozac and some other antidepressant drugs raise serotonin levels.

function: helps control alertness and arousal ; malfunctions: undersupply can depress mood.

function: a major inhibitory neurotransmitter ; undersupply linked to seizures, tremors, and insomnia.

function: a major excitatory neurotransmitter, also involved in memory ; malfunctions: oversupply can overstimulate brain, producing migraines or seizures (which is why some people avoid MSG, monosodium glutamate, in food).

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

tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue.

an amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.

a series of x-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body. Also called CAT SCAN.

a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.

a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain.

the oldest part and central core of the brain, beginning where the spinal cord swells as it enter the skull; the brainstem is responsible for automatic survival functions.

the base of the brainstem; controls heartbeat and breathing

a 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.

the "little brain" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance.

a doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres; associated with emotions such as fear and aggression and drives such as those for food and sex. Includes the hippocampus, amygdala, and hypothalamus.

two almond-shaped neural clusters that are components of the limbic system and are linked to emotion.

the intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the body's ultimate control land information-processing center.

cells in the nervous system that support, nourish, and protect neurons.

the portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgements.

the portion of the cerebral cortex lying at the top of the head and toward the rear; includes the sensory cortex.

the portion of the cerebral cortex lying at the back of the head; includes the visual areas, which receive visual information from the opposite visual field.

the portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each of which receives auditory information primarily from the opposite ear.

an area at the rear of the frontal lobes that controls voluntary movements.

the area at the front of the parietal lobes that registers and processes body sensations.

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.

impairment of language, usually caused by left hemisphere damage either to Broca's area (impairing speaking) or to Wernicke's area (impairing understanding)

controls language expression - an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech.

controls language reception - a brain area involved in language comprehension and expression; usually in the left temporal lobe

the brain's capacity for modification, as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development.

the large band of neural fibers connecting the two brain hemispheres and carrying messages between them.

a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them.

the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream.

chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another.

a pair of endocrine glands just above the kidneys. The adrenals secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to arouse the body in times of stress.

the endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.

a branch of psychology that studies physical, cognitive, and social change throughout the life span

the fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo.

the developing human organism from about 2 weeks after fertilization through the second month.

the developing human organism from 9 weeks after conception to birth

agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm.

physical and cognitive abnormalities in children caused by a pregnant woman's heavy drinking. In severe cases, symptoms include noticeable facial misproportions

decreasing responsiveness with repeated stimulation. As infants gain familiarity with repeated exposure to a visual stimulus, their interest wanes and they look away sooner.

biological growth processes that enable orderly changes in behavior, relatively uninfluenced by experience.

all the mental activities associated with thinking, knowing, remembering, and communicating.

a concept or framework that organizes and interprets information.

interpreting our new experience in terms of our existing schemas

adapting our current understandings (schemas) to incorporate new information.

in Piaget's theory, the stage (from birth to about 2 years of age) during which infants know the world mostly in terms of their sensory impressions and motor activities.

the awareness that things continue to exist even when not perceived.

in Piaget's theory, the stage (from about 2 to 6 or 7 years of age) during which a child learns to use language but does not yet comprehend the mental operations of concrete logic.

the principle (which Piaget believed to be a part of concrete operational reasoning) that properties such as mass, volume, and number remain the same despite changes in the forms of objects.

in Piaget's theory, the preoperational child's difficulty taking another's point of view.

people's ideas about their own and others' mental states-about their feelings, perceptions, and thoughts, and the behaviors these might predict.

in Piaget's theory, the stage of cognitive development (from about 6 or 7 to 11 years of age) during which children gain the mental operations that enable them to think logically about concrete events.

in Piaget's theory, the stage of cognitive development (normally beginning about age 12) during which people begin to think logically about abstract concepts.

a disorder that appears in childhood and is marked by deficient communication, social interaction, and understanding of others' states of mind.

the fear of strangers that infants commonly display, beginning by about 8 months of age.

an emotional tie with another person; shown in young children by their seeking closeness to the caregiver and showing distress on separation.

an optimal period shortly after birth when an organism's exposure to certain stimuli or experiences produces proper development.

the process by which certain animals form attachments during a critical period very early in life.

according to Erik Erikson, a sense that the world is predictable and trustworthy; said to be formed during infancy by appropriate experiences with responsive caregivers.

all our thoughts and feelings about ourselves, in answer to the question, "Who am I?"

the transition period from childhood to adulthood, extending from puberty to independence.

the period of sexual maturation, during which a person becomes capable of reproducing.

the body structures (ovaries, testes, and external genitalia) that make sexual reproduction possible.

nonreproductive sexual characteristics, such as female breasts and hips, male voice quality, and body hair.

the first menstrual period.

our sense of self; according to Erikson, the adolescent's task is to solidify a sense of self by testing and integrating various roles.

the "we" aspect of our self-concept; the part of our answer to "Who am I?" that comes from our group memberships.

in Erikson's theory, the ability to form close, loving relationships; a primary developmental task in late adolescence and early adulthood.

for some people in modern cultures, a period from the late teens to early twenties, bridging the gap between adolescent dependence and full independence and responsible adulthood.

the time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines.

a study in which people of different ages are compared with one another.

research in which the same people are restudied and retested over a long period

our accumulated knowledge and verbal skills; tends to increase with age.

our ability to reason speedily and abstractly; tends to decrease during late adulthood.

the culturally preferred timing of social events such as marriage, parenthood, and retirement.

Although common sense often serves us well, we are prone to hindsight bias. We also are routinely overconfident of our judgments, thanks partly to our bias to seek information that confirms them. Although limited by the testable questions it can address, scientific inquiry can help us sift reality from illusion and restrain the biases of our unaided intuition.

The three components of the scientific attitude are a curious eagerness to skeptically scrutinize competing ideas and an open-minded humility before nature. This attitude carries into everyday life as critical thinking, which examines assumptions, discerns hidden values, evaluates evidence and assesses outcomes. Putting ideas, even crazy-sounding ideas, to the test helps us winnow sense from nonsense.

Psychological theories organize observations and imply predictive hypotheses. After constructing precise operational definitions of their procedures, researchers test their hypotheses, validate and refine the theory, and, sometimes, suggest practical applications. If other researchers can replicate the study with similar results, we can then place greater confidence in the conclusion.

Psychologists observe and describe behavior using individual case studies, surveys among random samples of a population, and naturalistic observations. In generalizing from observations, remember: representative samples are a better guide than vivid anecdotes.

Scatterplots help us to see correlations. A positive correlation indicates the extent to which two factors rise together. In a negative correlation, one item rises as the other falls. An association indicates the possibility of a cause-effect relationship, but it does not prove the direction of the influence, or whether an underlying third factor may explain the correlation.

Illusory coreelations are random events that we ntoice and falsely assume are related. Patterns or sequences occur naturally in sets of random data, but we tend to interpret these patterns as meaningful connections, perhaps in an attempt to make sense of the world around us.

To discover cause-effect relationships, psychologists conduce experiements, manipulating one ore more factors of interest controlling other factors. Random assignment minimizes preexisting differences between the experimental group (exposed to the treatment) and the control group (given a placebo or different version of the treatment). The independent varaible is the factor you manipulate to study its effect. The dependent variable is the factor you measure to discover any changes that occur in response to these manipulations. Studies may use a double-blind procedure to avoid the placebo effect and reseracher's bias.

Three measures of central tendency are the median, the mode and the mean. Measures of variation tell us how similar or diverse data are. A range describes the gap between the highest and lowest scores. The more useful measure, the standard deviation, states how much scores vary aound the mean, or average, score. THe normal curve is a bell0shaped curve that describes the distribution of many types of data.

• Three principles are worth remembering: 1. Representative samples are better than biased samples. 2. Less-variable observations are more reliable than those that are more variable. 3. More cases are better than fewer.
• When averages from two samples are each reliable measures of their own populations, and the idfference between them is relatively large, we can assume that the result is statistically significant-that it did not occur by chance alone.

By intentionally creating a controlled, artifical environment in the lab, reserachers aim to test theoretical principles. These general principles help explain everyday behaviors.

Attitudes and behaviors vary across cultures, but the underlying principles vary much less because of our human kinship. Although gender differences tend to capture attention, it is important to remember our greater gender similiarities.

Some psychologists are primarily interested in animal behavior. Others study animals to better understand the physiological and psychological processes shared by humans. Under ethical and legal guidelines, animals used in experiements rarely experience pain. Nevertheless, animal rights groups raise an important issue: even if it leads to the relief of human suffering, is an animals temporary suffering justified?

Researchers may temporarily stress or deceive people in order to learn something important. Professional ethical standards provide guidelines concerning the treatment of both human and animal participants.

Psychologists' values influence their choice of research topics, their theories and observations, their labels for behavior and their professional advice. Applications of psychology's principles have been used mainly in the service of humanity.

Neurons are the elementary components of the nervous system, the body's speedy electrochemical information system. Sensory neurons carry incoming information from sense receptors to the brain adn spinal cord, and motor neurons carry information from the brain and spinal cord out to the muscles 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-electrity process. The neuron's reaction is an all or none process.

When actional 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 neuron. 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.

Each neurotransmitter travels a designed path in the brain and has a particular effect on behavior and emotions. Acetylcholine affects muscle action, learning and memory. Endorphins are natural opiates released in response to pain and exercise. Drugs and other chemicals affect communication at the synapse. Agonists excite by mimicking particular neurotransmitters or by blocking their reuptake. Antagonists inhibit a particular neurotransmitter's release or block its effect.

One major division of the nervous system is the central nervous system, the brain and spinal cord. The other is the peripheral nervous system, 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 enables voluntary control of the skeletal muscles. The autonomic nervous system, through its sympathetic and parasympathetic divisons, controls involuntary muscles and glands. Neurons cluster into working networks.

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 system'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 influence the brain.

Clinical observations and lesioning reveal the general effects of brain damage. MRI scans now reveal brain structures, and EEG, PET, and fMRI recordings reveal brain activity.

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 formation (which affects arousal). The thalamus, the brain's sensory switchboard, sits above the brainstem, coordinates muscle movement and help sprocess sensory information. The limbic system is linked to emotions, memory and drive. Its neural centers include the amygdala (involved in responses of aggression and fear) and the hypothalamus (involved in various bodily maintenance functions, pleasurable rewards and the control of the hormonal system). The pituitary (the master's gland) controls the hypothalamus by stimulating it to trigger the release of hormones. The hippocampus processes memory.

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 control voluntary movements. The sensory cortex registers and processes body sensations. Body parts requiring precise control (in the motor 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 association areas, which integrate information involved in learning, remembering, thinking, and other higher-level functions.

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 neurogensis (forming new neurons).

Split-brain research (experiments on people with a severed corpus 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.

About 10% of us are left-handed. Almost all right-handers process speech in the left hemisphere, as do more than half of all left-handers.

Many psychologists believe that hypnosis is a form of normal social influence and that hypnotized people act out the role of "good subject." Other psychologists viwe hypnosis as a dissociation. A unified account of hypnosis melds these two views and studies how brain activity, attention and social influences interact in hypnosis.

Psychoactive drugs alter perceptions and moods. Their continued use produces tolerance (requiring larger doses to achieve the same effect) and may lead to physical or psychological dependence. Addiction is compulsive drug craving and use. Three common misconceptions about addiction are that addictive drugs quickly corrupt; therapy is always required to overcome addictions and the concept of addiction can meaningfully be extended beyond chemical dependence to a wide range of other behaviors.

Depressants, such as alcohol, barbituarates, and the opiates, dampen neural activity and slow body functions. Alcohol tends to disinhibit-it increases the likelihood that we will act on our impulses, whether harmful or helpful. Alcohol also slows nervous system activity and impairs judgment, disrupts memory processes by suppressing REM sleep, and reduces self-awareness. User expectations strongly influence alcohol's behavioral effects.

Stimulants-caffine, nicotine, the amphetamines, cocain and ecstasy-excite neural activity and speed up body functions. All are highly addictive. Nicotine's effects make smoking a difficult habit to kick, but the percentage of Americans who smoke is neverthless decreasing. Continued use of methamphetamine may permanently reduce dopamine producation. Cocaine gives users a 15-30 minute high, followed by a crash. Its risks include cardiovascular stress and suspiciousness. Ectasy is a combined stimulant and mild hallucinogen that produces a euphoric high and feelings of intimacy. Its users risk immune system suppression, permanent damage to mood and memory, and (if taken during physical activity) dehydration and escalating body temperatures.

Hallucinogens-such as LSD and marijuana-distort perceptions to evoke hallucinations-sensory images in the absence of sensory input. The user's mood and expectations influence the effects of LSD, but common experiences are hallucinations and emotions varying from euphoria to panic. Marijuana's main ingredient, THC, may trigger feelings of disinhibition, euphoria, relaxation, relief from pain, and intense sensitivity to sensory stimuli. It may also increase feelings of depression or anxiety, impair motor coordination and reaction time, disrupt memory formation, and damage lung tissue (because of the inhaled smoke).

Psychological factors (such as stress, depression, and hope-lessness) and social factors (such as peer pressure) combine to lead many people to experiement with-and sometimes become dependent on-drugs. Cultural and ethnic groups have differing rates of drug use. Some people may be biologically more liekly to become dependent on drugs such as alcohol. Each type of influence-biological, psycholoigcal, and social-cultural offers a possible path for drug prevention and treatment programs.

Many people who have survived a brush with death, such as through cardiac arrest, report near death experiences. These sometimes involve out of body sensations and seeing or traveling towards a bright light. Some researchers believe that such experiences closely parallel reports of hallucinations and may be products of a brain under stress. Others reject this analysis.

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 environmental nurture, and the interaction between them (meaning that the effect of each depends on the other). The stability of temperament suggests a genetic predisposition.

Heritability describes the extent to which variation among memebers 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 poeple today are taller than a century ago.

molecular geneticists study the molecular structure and function of genes. Psychologists and molecular geneticists are cooperating to identify specific genes-or more often, teams of genes-that put people at risk for disorders.

Evolutionary psychologists seek to undersatnd 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.

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 healty, fertile-appearing partners increases their chances of spreading their genes widely. Because women incubate and nurse babies, they increase their own and their children's chances of survivial by searching for mates with the resourees and the potential for long-term investment in their joint offspring.

Critics argue that evolutionary psychologists start with an effect and work backward to an explanation, that the evolutionary perspectitve 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 overcoem them. They also cite the value of testable predictions based on evolutionary principles, as well as the coherence and explanatory power of those principles.

During maturation, a child's brain chagnes as neural connections increase in areas associated with stimulating activity, and unused synapses degenerate. Parents influence their children in areas such as manners and policial 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.

Cultural norms are rules for accepted and expected behaviors, ideas, attiduteds, 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.

Cultures based on self-reliant individualism, like those of most of the US, Canada, Austrailia, 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 identify 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.

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.

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 characterisitics, 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.

Developmental psychologists study physical, mental and social changes throughout the life span. The life cycle begins at conception, when one sperm cell unites with an egg to form a zygote. Attached to the uterine wall, the developing embryo's body organs begin to form and function. By 9 weeks, the fetus is recognizably human. Teratogens are potentially harmful agents that can pass through the placental screen and harm the developing embryo or fetus, as happens with fetal alcohol syndrome.

Newborns are born with sensory equipment and reflexes that facilitate their survival and their social interactions with adults. For example, they quickly learn to discriminate their mother's smell and sound. Researchers use techniques that test habituation, such as the novelty-preference procedure, to explore infants' abilities.

The brain's nerve cells are sculpted by heredity and experience; their interconnections multiply rapidly after birth. Our complex motor skill-sitting, standing, walking-develop in a predictable sequence whose timing is a function of individual maturation and culture. We lose conscious memories of experiences from before about age 3 1/2, in part because major areas of the brain have not yet matured.

Piaget proposed that through assimilation and accommodation, children actively construct and modify their undersatnding of the world. They form schemas that help them organize their experiences. Progressing from the simplicity of the sensorimotor stage of the first two years, in which they develop object permanence, children move to more complex ways of thinking. In the preoperational stage they develop a theory of mind(absent in children with autism), but they are egocentric and unable to perform simple logical operations. At about age 6 or 7, they enter the concrete operational stage and can perform concrete operations, such as those required to comprehend the pincriple of conservation. By about age 12, children enter the formal operational stage and can reason systematically. Research supports the sequence Piaget proposed for the unfolding of human cognition, but it also shows that young children are more capable, and their development more continuous than he believed.

At about 8 months, infants separated from their caregivers display stranger anxiety. Infants form attachments not simpy because parents gratify biological needs but, more important, because they are comfortable, familiar, and responsive. Ducks and other animals have a more rigid attachment process, called imprinting, that occurs during a critical period. Neglect or abuse can disrupt the attachment process. Infant's differing attachment styles reflect both their individual temperament and the responsiveness of their parents and child-care providers.

Attachment has been studied in strange situation experiments, which show that some children are securely attached to others are insecurely attached. Sensitive, responsive parents tend to have securely attached children. Adult relationships seem to refelct the attachment styles of early childhood, lending support to Erikson's idea that basic trust is formed in infancy by our experiences with responsive caregivers.

Children are very resilient. But those who are moved repeatedly, severly neglected by their parents, or otherwise prevented from forming attachments by age 2 may risk for attachment problems. Quality day care, with responsive adults interacting with children in a safe and stimulating environment, does not appear to harm children's thinking and language skills. Some studies have linked extensive time in daycare with increased aggressiveness and defiance, but other factors-the child's temperament, the parents sensitivity, and the family's economic and educational levels and culture-also matter.

Self-concept, a sense of one's indentity and personal worth, emerges gradually. At 15 to 18 months, children recognize themselves in a mirror. By school age, they can describe many of their own traits, and by age 8 to 10 their self-image is stable. Parenting styles-authoritarian, permissive and authoritative- reflect varyign degrees of control. Children with high self-esteem tend to have authoritive parents and to be self-reliant and socially competent, but the direction of cause and effect in this relationship is not clear.

Adolescence is the transition period between puberty and social independence. DUring these years, both primary and secondary sex characteristics develop dramatically. Boys seem to benefit from "early" maturation, girls from "late" maturation. The brain's frontal lobes mature during adolescence and the realy twenties, enabling imporved judgment, impulse control and long-term planning.

Piaget theorized that adolescents develop a capacity for formal operations and that this development is the foundation for moral judgment. Kohlberg proposed a stage theory of moral reasoning, from a preconventional morality of self-interest, to a conventional morality concerned with upholding laws and social rules, to (in some people) a postconventional morality of universal ethical principles. Kohlberg's critics note that morality lies in actions and emotions as well as thinking, and that his postconventional level represents morality from the perspective of individualist, middle-class males.

Erikson theorized that a chief task of adolescence is solidifying one's self-one's identity. This often means "trying on" a number of idfferent roles. During adolescence, parental influence diminishes and peer influence increases.

The transition from adolescence to adulthood is now taking longer. Emerging adulthood is the period from age 18 to the mid-twenties, when many young people are not yet fully independent. But critics note that this stage is found mostly in today's Western cultures.

Muscular strength, reaction time, sensory abilities, and cardiac output begin to decline in the late twenties and continue throughout middle and late adulthood. Around age 50, menopuase ends women's period of fertility but usually does not trigger psychological problems or interfere with a satisfying sex life. Men do not undergo a simliar sharp drop in hormone levels or fertility.

As the years pass, recall begins to decline, especially for meaningless information, but recognition, memory remains strong. Cross-sectional and longitudinal studies have shown that fluid intelligence declines in later life but crystallized intelligence does not.

Adults do not progress through an orderly sequence of age related social stages.More important are life events, and the loosening of strict dictates of the social clock-the culturally preferred timing of social events. The dominant themes of adulthood are love and work, which Erkison called intimacy and generativity. Life satisfaction tends to remain high across the life spam.

Learning is a relatively permanent change in an organism's behavior due to experience. In associative learning, we learn to associate two stimuli (as in classical conditioning) or a response and its consequences (as in operant conditioning). In observational learning, we learn by watching others' experiences and examples.

Classical conditioning is a type of learning in which an organism comes to associate stimuli. Pavlov's work on classical conditioning laid the foundation for behaviorism, the view that psychology should be an objective science that studies behavior without reference to mental processes.

In classical conditioning, a UR is an event that occurs naturally (such as salivation), in response to some stimulus. A US is something that naturally and automatically (without learning) triggers the unlearned response (as food in the mouth triggers salivation). A CS is a previously irrelevant stimulus (such as a bell) that, through learning, comes to be associated with some unlearned response (salivating). A CR is the learned response (salivating) to the originally irrelevant but now coniditioned stimulus.

In classical conditioning, acquisition is associating a CS with the US. Acquisition occurs most readily when a CS is presented just before (ideally, about a half-seond before) a US, preparing the organism for the upcoming event. This finding supports the view that classical coniditioning is biologically adaptive. Extinction is diminished responding when the CS no longer signals an impending US. Spontaneous revoery is the appearance of a formerly extinguished response, following a rest period. Generalization is the tendency to respond to stimuli that are similar to a CS. Discrimination is the learned ability to distinguish between a CS and other irrelevant stimuli.

The behaviorists optimism that in any species, any response can be conditioned to any stmiulus has been tempered. Conditioning principles, we now know, are cognitively and biologically constrained. In classical conditioning, animals learn when to expect a US, and they may be aware of the link between stimuli and responses. Moreover, because of biological predispositions, learning some associations is easier than learning others. Learning is adaptive: each species learns behaviors that aid its survival.

Pavlov taught us that significant psychological phenomena can be studied objectively, and that classical conditioning is a basic form of learning that applies to all species. Later research modified this finding somewhat by showing that in many species cognition and biological predispositions place some limits on conditioning.

Classical conditioning techniques are used in treatment programs for those recovering from cocaine and other drug abuse and to condition more appropriate responses in therapy for emotional disorders. The body's immune system also appears to respond to classical conditioning.

In operant conditioning, an organism learns associations between its own behavior and resulting events; this form of conditioning involves operant behavior (behavior that operates on the environment, producing consequences). In classical conditioning, the organism forms associations between stimuli-behaviors it does not control; this form of conditioning involves respondent behavior (automatic responses to some stimulus). Others found that the behavior of rats or pigeons placed in an operant chamber can be shaped by using reinforcers to guide closer and closer approximations of the desired behavior.

Positive reinforcement adds something desirable to increase the frequency of a behavior. Negative reinforcement removes something undesirable to increase the frequency of a behavior. Primary reinforcers (such as receiving food when hungry or having nausea end during an illness) are innately satisfying-no learning is required. Conditioned reinforcers (such as cash) are satisfying because we have learned to associate them with more basic rewards (such as food or medicine we buy with them) offer immediate payback; delayed reinforcers (such as a weekly paycheck) require the ability to delay gratification.

In continuous reinforcement (reinforcing desired responses every time they occur), learning is rapid, but so is extinction if rewards cease. In partial (intermittent) reinforcement, initial learning is slower, but the behavior is much more resistant to extinction. Fixed-ratio schedules offer rewards after a set number of responses; variable-ratio schedules, after an unpredictable number. Fixed-interval schedules offer rewards after set time periods; variable-interval schedules, after unpredictable time periods.

Punishment attempts to decrease the frequency of a behavior (a child's disobedience) by administering an undesireable consequence (such as spanking) or withdrawing something desirable (such as taking away a favorite toy). Undesirable side effects can include suppressing rather than changing unwanted behaviors, teaching aggression, creating fear, encouraging discrimination (so that the undesirable behavior appears when the punisher is not present), and fostering depression and feelings of helplessness.

Skinner underestimated the limits that cognitive and biological constraints place on conditioning. Research on cognitive mapping and latent learning demonstrate the importance of cognitive processes in learning. Excessive rewards can undermine intrinsic motivation. Training that attempts to override biological constraints will probably not endure because teh animals will revert to their predisposed patterns.

In school, teachers can use shaping techniques to guide students' behaviors, and they can use interactive software and web sites to provide immediate feedback. In sports, coaches can build players' skills and self-confidence by rewarding small improvements. At work, managers can boost productivity and morale by rewarding well-defined and achievable behaviors. At home, parents can reward behaviors they consider desirable, but not those that are undesirable. We can shape our own behaviors by stating our goals, monitioring the frequency of desired behaviors, reinforcing desired behaviors, and cutting back on incentives as behaviors become habitual.

In observational learning, we observe and imitate others. Mirror neurons, located in the brain's frontal lobes, demonstrate a neural basis for observational learning. They fire when we perform certain actions (such as responding to pain or moving our mouth to form words), or when we observe someone else performing those actions.

Children tend to imitate what a model does and says, whether the behavior being modeled is prosocial (positive, constructive, and helpful) or antisocial. If a model's actions and words are inconsistent, children may imitate the hypocrisy they observe.

Automatic processing happens unconsciously, as we absorb information (space, time, frequency, well-learned material) in our environment. Effortful processing (of meaning, imagery, organization) requires conscious attention adn deliberate effort. The spacing effect is our tendency to retain information more easily if we practice it repeatedly (spaced study) than if we practice it in one long session (massed practice, or cramming). The serial position effect is our tendency to recall the first item (the primary effect) and the last item (the recency effect) in a long list more easily than we recall the intervening items.

Visual encoding (of images) and acoustic encoding (of sounds) engage shallower processing than semantic encoding (of meaning). We process verbal information best when we make it relevant to ourselves (the self-reference effect). Encoding imagery, as when using some mnemonic devices, also supports memory, because vivid images are memorable. Chunking and hierarchies help organize information for easier retrieval.

The instinct/evolutionary perspective explores genetic influences on complex behaviors. Drive-reduction theory explores how physiological needs create aroused tension states (drives) that direct us to satisfy those needs. Arousal theory proposes a motivation for behaviors, such as curiosity-driven behaviors, that do not reduce physiological needs. Maslow's hierarchy of needs proposes a pyramid of human needs, from basic needs such as hunger and thirst up to higher-level needs such as actualization and transcendence.

Hunger's pangs correspond to the stomach's contractions, but hunger also has other causes. Appetite hormones include insulin (controls blood glucose), leptin (secreted by fat cells), orexin (secreted by the hypothalamus), ghrelin (secreted by an empty stomach), obestatin (screted by the the stomach) and PYY (secreted by digestive tract). Two areas of the hypothalamus regulate the body's weight by affecting feelings of hunger and satiety. The body may have a set point (a biologically fixed tendency to maintain an optimum weight( or a looser seetling point (also influenced by the environment).

Hunger also reflects learning, our memory of when we last ate and our expectation of when we should eat again. Humans as a species prefer certain tastes (such as sweet and satly) but we satisfy those preferences with specific foods prescribed by our situation and our culture. Some taste preferences, such as the avoidance of new foods or of foods that have made us ill, have survival value.

In these eating disorders, psychological factors may overwhelm the homeostatic drive to maintain a balanced internal state. People with anorexia nervosa (usually adolescent females) starve themsleves but continue to diet because they view themselves as fat. Those with bulimia nervosa binge and purge in secret (primarily females in their teens and twenties). Those with binge-eating disorder binge but do not purge. Cultural pressures, low self-esteem, and negative emotions interact with stressful life experiences to produce eating disorders. Twin research also indicates, however, that these disorders may have a genetic component.

The lack of exercise combined with the abundance of high calorie fodo has led to increased rates of obesity, showing the influence of environment. Twin and adoption studies indicate that body weight is also genetically influenced (in the number of fat cells and basal metabolic rate). Thus, genes and environment interact to produce obesity. Those wishing to lose weight are advised to make a lifelong change in habits, minimize exposure to tempting food cues, boost energy expenditure through exercise, eat healthy foods, space meals throughout the day, beware of the binge, adn forgive the occasional lapse.

Masters and Johnson described four stages in the human sexual response cycle: excitement, plateau, orgasm (which seems to involve similar feelings and brain activity in males and females), and resolution. During the resolution phase, males experience a refractory period, during which renewed arousal and orgasm are impossible. Sexual disorders (problems that consistently impair sexual arousal or functioning) can be sucessfully treated, often by behaviorally oriented therapy or drug therapy.

The female estrogen and male testosterone hormones influence human sexual behavior less directly that they influence non human animals. Unlike other mammalian females, wome's sexuality is more responsive to testosterone level than to estrogen level. Short-term shifts in testosterone level are normal in men, partly in response to stimulation.

Erotic material and other external stimuli can trigger sexual arousal in both men and women, although the activated brain areas differ somewhat. Men respond more specifically to sexual depictions involving their preferred sex. Sexually explicit material may lead people to perceive their partners as comparatively less appealing and to devalue their relationships. Sexually coercive material tends to increase viewers' acceptance of rape and violence toward women. Fantasies (imagined stimuli) also influence sexual arousal.

Rates of teen intercourse vary from culture to culture and era to era. Factors contributing to teen pregnancy include ignorance; minimal communication about contraception with parents, partners, and peers; guilt related to sexual activity alcohol use; and mass media norms of unprotected and impulsive sexuality. STIs have spread rapidly. Attempts to protect teens through comprehensive sex-education programs include contraceptive and abstinence education. High intellegence, religiosity, father presence, and participation in service learning programs are predictors of teen sexual restraint.

Surveys can tell us how many people (about 3%) are attracted to their own sex, but statistics cannot decide issues of human rights. There is no evidence that environmental influences determine sexual orientation. Biological influences may include the presence of same-sex behaviors in many animal species, straight-gay differences in body and brain characteristics, higher rates in certain families and in identical twins, and exposure to certain hormones during critical periods of prenatal developmental.

Scientific research on sexual motivation does not attempt to define the personal meaning of sex in our lives, but sex research and education are not value-free.

Our need to affiliate or belong had survival value for our ancestors' chances, which may explain why humans in every society live in groups. Societies everywhere contorl behavior with the threat of ostracism-excluding of shunning others. When socially excluded, people may engage in self-defeating behaviors (performing below their ability) or in antisocial behaviors.

Personnel psychologists work with organizations to devise selection methods for new emplyees, recruit and evaluate applicants, design and evaluate training programs, identify people's strengths, analyze job content, and appraise individual and organizational performance. Subjective interviews foster the interviewer illusion; structured interviews pinpoint job-relevant strengths and are better predictors of performance. Checklists, graphic rating scales, and behavior rating scales are useful performance appraisal methods.

Organizational psychologists examine influences on worker satisfaction and productivity and facilitate organizational change. Employee engagement tends to correlate with organizational success. Leadership style may be goal-orientated (task leadership) or group oriented (social leadership) or some combination of the two.