Psych It We Ball

Population

all those in a group being studied, from which samples may be drawn (Note: except for national studies, this does not refer to a countryś whole population).

Random Sample

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

Sampling Bias

a flawed sampling process that produces an unrepresentative sample

Self-Report Bias

bias when people report their behavior inaccurately

Social Desirability Bias

bias from people's responding in ways they presume a researcher expects or wishes

Survey

a non-experimental technique for obtaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group.

Naturalistic Observation

a non-experimental technique of observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation

Case Study

a non-experimental technique in which one individual or group is studied in depth in the hope of revealing universal principles

Replication

repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding can be reproduced.

Operational Definition

a carefully worded statement of the exact procedures (operations) used in a research study. For example, human intelligence may be operationally defined as what an intelligence test measures. (Also known as operationalism).

Falsifiable

the possibility that an idea, hypothesis, or theory can be disproven by observation or experiment

Hypothesis

A testable prediction, often implied by a theory.

Critical Thinking

Thinking that does not automatically accept arguments and conclusions. Rather, it examines assumptions, appraises the source, discerns hidden biases, evaluates evidence, and assesses conclusions.

Hindsight Bias

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

Peer Reviewers

scientific experts who evaluate a research article's theory, originality, and accuracy

Theory

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

Regression Toward the Mean

the tendency for extreme or unusual scores to fall back (regress) toward their average.

Scatterplot

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 scatter suggests the strength of the correlation.

Random Assignment

assigning participants to experimental and control conditions by chance, thus minimizing preexisting differences between those assigned to the different groups

Illusory Correlation

perceiving a relationship where none exists, or perceiving a stronger-than-actual relationship

Correlation Coefficient

a statistical index of the relationship between two variables (from -1 to +1)

Variable

anything that can vary and is feasible and ethical to measure.

Correlation

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

Single-Blind Procedure

an experimental procedure in which the research participants are ignorant (blind) about whether they have received the treatment or a placebo.

Double-Blind Procedure

an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.

Experimental Group

In an experiment, the group that is exposed to the treatment, that is, to one version of the independent variable.

Control Group

In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.

Experiment

A research method in which an investigator manipulates one or more factors (independent variables) to observe the effect on some behavior or mental process (the dependent variable).

Placebo Effect

experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent.

Independent Variable

in an experiment, the factor that is manipulated; the variable whose effect is being studied

Confounding Variable

in an experiment, a factor other than the factor being studied that might influence a study's results.

Experimenter Bias

bias caused when researchers may unintentionally influence results to confirm their own beliefs

Dependent Variable

in an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated

Validity

the extent to which a test or experiment measures or predicts what it is supposed to

descriptive statistics

numerical data used to measure and describe characteristics of groups. Includes measures of central tendency and measures of variation.

histogram

a bar graph depicting a frequency distribution

mode

the most frequently occurring score(s) in a distribution

mean

the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores

median

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

percentile rank

the percentage of scores that are lower than a given score

skewed distribution

a representation of scores that lack symmetry around their average value

range

the difference between the highest and lowest scores in a distribution

standard deviation

a computed measure of how much scores vary around the mean score

normal curve

the symmetrical bell-shaped curve that describes the distribution of many physical and psychological attributes. Most scores fall near the mean (about 68 percent fall within one standard deviation of it) and fewer and fewer scores lie near the extremes. (Also called a normal distribution.)

inferential statistics

numerical data that allow one to generalize- to infer from sample data the probability of something being true of a population

meta-analysis

a statistical procedure for analyzing the results of multiple studies to reach an overall conclusion

statistical significance

a statistical statement of how likely it is that a result (such as a difference between samples) occurred by chance, assuming there is no difference between the populations being studied.

effect size

the strength of the relationship between two variables. The larger the effect size, the more one variable can be explained by the other.

informed consent

giving potential participants enough information about a study to enable them to choose whether they wish to participate

debriefing

the postexperimental explanation of a study, including its purpose and any deceptions, to its participants

quantitative research

a research method that relies on quantifiable, numerical data

qualitative research

a research method that relies on in-depth, narrative data that are not translated into numbers

nature-nurture issue

the longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors. Today's science sees traits and behaviors arising from the interaction of nature and nurture

natural selection

the principle that inherited traits enabling an organism to survive and reproduce in a particular environment will (in competition with other trait variations) most likely be passed on to succeeding generations

evolutionary psychology

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

behavior genetics

the study of the relative power and limits of genetic and environmental influences on behavior

mutation

a random error in gene replication that leads to a change

environment

every nongenetic influence, from prenatal nutrition to our experiences of the people and things around us

heredity

the genetic transfer of characteristics from parents to offspring

genes

the biochemical units of heredity

genome

the complete instructions for making an organism

identical (monozygotic) twins

individuals who developed from a single fertilized egg that split in two, creating two genetically identical organisms

fraternal (dizygotic) twins

individuals who developed from separate fertilized eggs. They are genetically no closer than ordinary siblings, but they shared a prenatal environment

interaction

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

epigenetics

"above" or "in addition to" (epi) genetics; the study of the molecular mechanisms by which environments can influence genetic expression (without a DNA change)

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)

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.

Nerves

bundled axons that form neural "cables" connecting the central nervous system with muscles, glands, and sense organs

Sensory (afferent) neurons

neurons that carry incoming information from the body's tissues and sensory receptors to the brain and spinal cord.

Motor (efferent) neurons

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

Interneurons

neurons within the brain and spinal cord that communicate internally and process information between the sensory inputs and motor outputs

Somatic nervous system

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

Autonomic nervous system (ANS)

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

parasympathetic nervous system

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

Reflex

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

neuron

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

cell body

the part of the neuron that contains the nucleus; the cell's life-support center.

dendrites

a neuron's often bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body.

axon

the segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands

myelin sheath

a fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to the next

glial cells (glia)

cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory.

action potential

a neural impulse; a brief electrical charge that travels down an axon

threshold

the level of stimulation required to trigger a neural impulse

refractory period

in neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state

all-or-none response

a neuron's reaction of either firing (with a full-strength response) or not firing.

synapse

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.

neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

reuptake

a neurotransmitter's reabsorption by the sending neuron

endorphins

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

agonist

a molecule that increases a neurotransmitter's action

antagonist

a molecule that inhibits or blocks a neurotransmitter's action

endocrine system

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

hormones

chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

biological psychology

the scientific study of the links between biological (genetic, neural, hormonal) and psychological processes

biophysical approach

an integrated approach that incorporates biological, psychological, and social-cultural levels of analysis

levels of analysis

the differing complementary views, from biological to psychological to social-cultural, for analyzing any given phenomenon

neuroplasticity

the brain's ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience

lesion

tissue destruction. Brain lesions may occur naturally (from disease or trauma), during surgery, or experimentally (using electrodes to destroy brain cells).