VOCABULARY FOR CHAPTER 1
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evidence-based treatment: A psychotherapy technique whose effectiveness has been
supported by empirical research.
Empiricism: The use of verifiable evidence as the basis for conclusions; collecting data
systematically and using it to develop, support, or challenge a theory. Also called
empirical method, empirical research.
Theory: A statement or set of statements that describes general principles about how
variables relate to one another.
Hypothesis: A statement of the specific result the researcher expects to observe from a
particular study, if the theory is accurate. Also called prediction.
data (plural; singular datum): A set of observations representing the values of some
variable, collected from one or more research studies.
Preregistered: A term referring to a study in which, before collecting any data, the
researcher has stated publicly what the study’s outcome is expected to be.
Replication: The process of conducting a study again to test whether the result is
consistent.
weight of the evidence: A conclusion drawn from reviewing scientific literature and
considering the proportion of studies that is consistent with a theory.
self-correcting: A process in which scientists make their research available for peer
review, replication, and critique, with the goal of identifying and correcting errors in the
research.
applied research: Research whose goal is to find a solution to a particular real-world
problem. See also basic research, translational research.
basic research: Research whose goal is to enhance the general body of knowledge,
without regard for direct application to practical problems. See also applied research,
translational research.
translational research: Research that uses knowledge derived from basic research to
develop and test solutions to real-world problems. See also applied research, basic
research.
Journal: A monthly or quarterly periodical containing peer-reviewed articles on a specific
academic discipline or subdiscipline, written for a scholarly audience. Also called
scientific journal.
Journalism: News and commentary published or broadcast in the popular media and
produced for a general audience.
Falsifiable: A feature of a scientific theory, in which it is possible to collect data that will
indicate that the theory is wrong.
Universalism: One of Merton’s four scientific norms, stating that scientific claims are
evaluated according to their merit, independent of the researcher’s credentials or
reputation. The same preestablished criteria apply to all scientists and all research. See
also communality, disinterestedness, organized skepticism.
Communality: One of Merton’s four scientific norms, stating that scientific knowledge is
created by a community, and its findings belong to the community. See also
universalism, disinterestedness, organized skepticism.
Disinterestedness: One of Merton’s four scientific norms, stating that scientists strive to
discover the truth whatever it is; they are not swayed by conviction, idealism, politics, or
profit. See also universalism, communality, organized skepticism.
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organized skepticism: One of Merton’s four scientific norms, stating that scientists
question everything, including their own theories, widely accepted ideas, and “ancient
wisdom.” See also universalism, communality, disinterestedness.
conceptual definition: A researcher’s definition of a variable at the theoretical level.
Also called construct. See also conceptual variable.
self-report measure: A method of measuring a variable in which people answer
questions about themselves in a questionnaire or interview.
observational measure: A method of measuring a variable by recording observable
behaviors or physical traces of behaviors. Also called behavioral measure.
physiological measure: A method of measuring a variable by recording biological data.
categorical variable: A variable whose levels are categories (e.g., male and female).
Also called nominal variable.
quantitative variable: A variable whose values can be recorded as meaningful
numbers.
ordinal scale: A quantitative measurement scale whose levels represent a ranked
order, and in which distances between levels are not equal (e.g., order of finishers in a
race). See also interval scale, ratio scale.
interval scale: A quantitative measurement scale that has no “true zero,” and in which
the numerals represent equal intervals (distances) between levels (e.g., temperature in
degrees). See also ordinal scale, ratio scale.
ratio scale: A quantitative measurement scale in which the numerals have equal
intervals and the value of zero truly means “none” of the variable being measured. See
also interval scale, ordinal scale.
Reliability: The consistency of the results of a measure.
Validity: The appropriateness of a conclusion or decision. See also construct validity,
external validity, internal validity, statistical validity.
test-retest reliability: The consistency in results every time a measure is used.
interrater reliability: The degree to which two or more coders or observers give
consistent ratings of a set of targets.
internal reliability: In a measure that contains several items, the consistency in a
pattern of answers, no matter how a question is phrased. Also called internal
consistency.
correlation coefficient r: A single number, ranging from –1.0 to 1.0, that indicates the
strength and direction of an association between two variables.
slope direction: The upward, downward, or neutral slope of the cluster of data points in
a scatterplot.
Strength: A description of an association indicating how closely the data points in a
scatterplot cluster along a line of best fit drawn through them.
average inter-item correlation (AIC): A measure of internal reliability for a set of items;
it is the mean of all possible correlations computed between each item and the others.
Cronbach’s alpha: A correlation-based statistic that measures a scale’s internal
reliability. Also called coefficient alpha.
face validity: The extent to which a measure is subjectively considered a plausible
operationalization of the conceptual variable in question.
criterion validity: An empirical form of measurement validity that establishes the extent
to which a measure is associated with a behavioral outcome with which it should be
associated.
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known-groups paradigm: A method for establishing criterion validity, in which a
researcher tests two or more groups who are known to differ on the variable of interest,
to ensure that they score differently on a measure of that variable.
convergent validity: An empirical test of the extent to which a self-report measure
correlates with other measures of a theoretically similar construct. See also discriminant
validity.
discriminant validity: An empirical test of the extent to which a self-report measure
does not correlate strongly with measures of theoretically dissimilar constructs. Also
called divergent validity. See also convergent validity.
content validity: The extent to which a measure captures all parts of a defined
construct.
Survey: A method of posing questions to people on the telephone, in personal
interviews, on written questionnaires, or via the Internet. Also called poll.
Poll: A method of posing questions to people on the telephone, in personal interviews,
on written questionnaires, or via the Internet. Also called survey.
open-ended question: A survey question format that allows respondents to answer any
way they like.
forced-choice question: A survey question format in which respondents give their
opinion by picking the best of two or more options.
Likert scale: A survey question format using a rating scale containing multiple response
options anchored by the specific terms strongly agree, agree, neither agree nor
disagree, disagree, and strongly disagree. A scale that does not follow this format
exactly is called a Likert-type scale.
semantic differential format: A survey question format using a response scale whose
numbers are anchored with contrasting adjectives.
leading question: A type of question in a survey or poll that is problematic because its
wording encourages one response more than others, thereby weakening its construct
validity.
double-barreled question: A type of question in a survey or poll that is problematic
because it asks two questions in one, thereby weakening its construct validity.
negatively worded question: A question in a survey or poll that contains negatively
phrased statements, making its wording complicated or confusing and potentially
weakening its construct validity.
response set: A shortcut respondents may use to answer items in a long survey, rather
than responding to the content of each item. Also called nondifferentiation.
Acquiescence: Answering “yes” or “strongly agree” to every item in a survey or
interview. Also called yea-saying.
fence sitting: Playing it safe by answering in the middle of the scale for every question
in a survey or interview.
socially desirable responding: Giving answers on a survey (or other self-report
measure) that make one look better than one really is. Also called faking good.
faking good: Giving answers on a survey (or other self-report measure) that make one
look better than one really is. Also called faking good.
faking bad: Giving answers on a survey (or other self-report measure) that make one
look worse than one really is.
observational research: The process of watching people or animals and systematically
recording how they behave or what they are doing.
observer bias: A bias that occurs when observer expectations influence the
interpretation of participant behaviors or the outcome of the study.
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observer effect: A change in behavior of study participants in the direction of observer
expectations. Also called expectancy effect.
masked design: A study design in which the observers are unaware of the experimental
conditions to which participants have been assigned. Also called blind design.
Reactivity: A change in behavior of study participants (such as acting less
spontaneously) because they are aware they are being watched.
unobtrusive observation: An observation in a study made indirectly, through physical
traces of behavior, or made by someone who is hidden or is posing as a bystander.
VOCABULARY FOR CHAPTER 2
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comparison group: A group in an experiment whose levels on the independent variable
differ from those of the treatment group in some intended and meaningful way. Also
called comparison condition.
Confound: A general term for a potential alternative explanation for a research finding;
a threat to internal validity.
Confederate: An actor who is directed by the researcher to play a specific role in a
research study.
Probabilistic: Describing the empirical method, stating that science is intended to
explain a certain proportion (but not necessarily all) of the possible cases.
availability heuristic: A bias in intuition, in which people incorrectly estimate the
frequency of something, relying predominantly on instances that easily come to mind
rather than using all possible evidence in evaluating a conclusion.
present/present bias: A bias in intuition, in which people incorrectly estimate the
relationship between an event and its outcome, focusing on times the event and
outacome are present, while failing to consider evidence that is absent and harder to
notice.
confirmation bias: The tendency to consider only the evidence that supports a
hypothesis, including asking only the questions that will lead to the expected answer.
bias blind spot: The tendency for people to think that compared to others, they
themselves are less likely to engage in biased reasoning.
empirical journal article: A scholarly article that reports for the first time the results of a
research study.
review journal article: An article summarizing all the studies that have been published
in one research area.
effect size: The magnitude, or strength, of a relationship between two or more variables.
Paywalled: Term referring to a peer-reviewed academic journal that the general public
must pay to access; only people who are members of subscribing institutions can access
the content.
open access: Term referring to a peer-reviewed academic journal that anyone, even the
general public, can read without paying for access.
Disinformation: A news story, photo, or video deliberately created to be false or
misleading.
meta-analysis: A way of mathematically averaging the effect sizes of all the studies that
have tested the same variables to see what conclusion that whole body of evidence
supports.
VOCABULARY FOR CHAPTER 3
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variable: An attribute that varies, having at least two levels, or values. See also
dependent variable, independent variable, manipulated variable, measured variable.
Level: One of the possible variations, or values, of a variable. Also called condition.
Constant: An attribute that could potentially vary but that has only one level in the study
in question.
measured variable: A variable in a study whose levels (values) are observed and
recorded. See also manipulated variable.
manipulated variable: A variable in an experiment that a researcher controls, such as
by assigning participants to its different levels (values). See also measured variable.
Construct: A variable of interest, stated at an abstract level, usually defined as part of a
formal statement of a psychological theory. See also conceptual variable.
conceptual variable: A variable of interest, stated at an abstract, or conversational,
level. Also called construct. See also conceptual definition.
operational definition: The specific way in which a concept of interest is measured or
manipulated as a variable in a study. Also called operationalization, operational variable.
operational variable: The specific way in which a concept of interest is measured or
manipulated as a variable in a study. Also called operationalization, operational variable.
Operationalize: To turn a conceptual definition of a variable into a specific measured
variable or manipulated variable in order to conduct a research study.
Claim: The argument a journalist, researcher, or scientist is trying to make.
frequency claim: A claim that describes a particular rate or degree of a single variable.
association claim: A claim about two variables, in which the value (level) of one
variable is said to vary systematically with the value of another variable.
Correlate: To occur or vary together (covary) systematically, as in the case of two
variables. See also correlational study, covariance.
correlational study: A study that includes two or more variables, in which all of the
variables are measured; can support an association claim.
positive association: An association in which high levels of one variable go with high
levels of the other variable, and low levels of one variable go with low levels of the other
variable. Also called positive correlation. See also curvilinear association, negative
association, zero association.
Scatterplot: A graphical representation of an association, in which each dot represents
one participant in the study measured on two variables.
negative association: An association in which high levels of one variable go with low
levels of the other variable, and vice versa. Also called inverse association, negative
correlation. See also curvilinear association, positive association, zero association.
zero association: A lack of systematic association between two variables. Also called
zero correlation. See also curvilinear association, positive association, negative
association.
causal claim: A claim arguing that a specific change in one variable is responsible for
influencing the value of another variable.
Validity: The appropriateness of a conclusion or decision. See also construct validity,
external validity, internal validity, statistical validity.
construct validity: An indication of how well a variable was measured or manipulated in
a study.
Generalizability: The extent to which the subjects in a study represent the populations
they are intended to represent; how well the settings in a study represent other settings
or contexts.
external validity: An indication of how well the results of a study generalize to, or
represent, individuals or contexts besides those in the study itself. See also
generalizability.
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statistical validity: The extent to which statistical conclusions derived from a study are
accurate and reasonable. Also called statistical conclusion validity.
point estimate: A single estimate of some population value (such as a percentage, a
correlation, or a difference) based on data from a sample.
confidence interval (CI): A given range indicated by a lower and upper value that is
designed to capture the population value for some point estimate (e.g., percentage,
difference, or correlation); a high proportion of CIs will capture the true population value.
margin of error of the estimate: In the context of a percentage estimate, an inferential
statistic providing a range of values that has a high probability of containing the true
population value. See also confidence interval.
Covariance: The degree to which two variables go together. Also one of three criteria
for establishing a causal claim, which states that, in a study’s results, the proposed
causal variable must vary systematically with changes in the proposed outcome variable.
See also internal validity, temporal precedence.
temporal precedence: One of three criteria for establishing a causal claim, stating that
the proposed causal variable comes first in time, before the proposed outcome variable.
See also covariance, internal validity.
internal validity : No confounding variables. One of three criteria for establishing a
causal claim; a study’s ability to rule out alternative explanations for a causal relationship
between two variables. Also called third-variable criterion. See also covariance, temporal
precedence.
Experiment: A study in which at least one variable is manipulated and another is
measured.
independent variable: In an experiment, a variable that is manipulated. In a multipleregression analysis, a predictor variable used to explain variance in the criterion
variable. See also dependent variable.
dependent variable: In an experiment, the variable that is measured. In a multipleregression analysis, the single outcome, or criterion variable the researchers are most
interested in understanding or predicting. Also called outcome variable. See also
independent variable.
random assignment: The use of a random method (e.g., flipping a coin) to assign
participants into different experimental groups.
VOCABULARY FOR CHAPTER 4
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Belmont Report Principles
o principle of respect for persons: An ethical principle from the Belmont Report
stating that research participants should be treated as autonomous agents and
that certain groups deserve special protection. See also principle of beneficence,
principle of justice.
o principle of beneficence: An ethical principle from the Belmont Report stating
that researchers must take precautions to protect participants from harm and to
promote their well-being. See also principle of justice, principle of respect for
persons.
o principle of justice: An ethical principle from the Belmont Report calling for a
fair balance between the kinds of people who participate in research and the
kinds of people who benefit from it. See also principle of beneficence, principle of
respect for persons.
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informed consent: The right of research participants to learn about a research project,
know its risks and benefits, and decide whether to participate.
anonymous study: A research study in which identifying information is not collected,
thereby completely protecting the identity of participants. See also confidential study.
confidential study: A research study in which identifying information is collected, but
protected from disclosure to people other than the researchers. See also anonymous
study.
institutional review board (IRB): A committee responsible for ensuring that research
using human participants is conducted ethically.
Deception: The withholding of some details of a study from participants (deception
through omission) or the act of actively lying to them (deception through commission).
data fabrication: A form of research misconduct in which a researcher invents data that
fit the hypothesis.
data falsification: A form of research misconduct in which a researcher influences a
study’s results, perhaps by deleting observations from a data set or by influencing
participants to act in the hypothesized way.
Plagiarism: Representing the ideas or words of others as one’s own; a form of research
misconduct.
self-plagiarism: A potentially unethical practice in which researchers recycle their own
previously published text, verbatim and without attribution, in a subsequent article.
bivariate correlation: An association that involves exactly two variables. Also called
bivariate association.
Mean: An arithmethic average; a measure of central tendency computed from the sum
of all the scores in a set of data, divided by the total number of scores.
effect size: The magnitude, or strength, of a relationship between two or more variables.
Replication: The process of conducting a study again to test whether the result is
consistent.
Outlier: A score that stands out as either much higher or much lower than most of the
other scores in a sample.
restriction of range: In a bivariate correlation, the absence of a full range of possible
scores on one of the variables, so the relationship from the sample underestimates the
true correlation.
curvilinear association: An association between two variables which is not a straight
line; instead, as one variable increases, the level of the other variable increases and
then decreases (or vice versa). See also positive association, negative association, zero
association.
directionality problem: In a correlational study, the occurrence of both variables being
measured around the same time, making it unclear which variable in the association
came first. See also temporal precedence.
third-variable problem: In a correlational study, the existence of a plausible alternative
explanation for the association between two variables. See also internal validity.
spurious association: A bivariate association that is attributable only to systematic
mean differences on subgroups within the sample; the original association is not present
within the subgroups.
Moderator: A variable that, depending on its level, changes the relationship between
two other variables.
statistically significant: In NHST, the conclusion assigned when when p < .05; that is,
when it is unlikely the result came from the null-hypothesis population.
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multivariate design: A study designed to test an association involving more than two
measured variables.
longitudinal design: A study in which the same variables are measured in the same
people at different points in time.
cross-sectional correlation: In a longitudinal design, a correlation between two
variables that are measured at the same time.
Autocorrelation: In a longitudinal design, the correlation of one variable with itself,
measured at two different times.
cross-lag correlation: In a longitudinal design, a correlation between an earlier
measure of one variable and a later measure of another variable.
multiple regression: A statistical technique that computes the relationship between a
predictor variable and a criterion variable, controlling for other predictor variables. Also
called multivariate regression.
control for: Holding a potential third variable at a constant level (statistically or
experimentally) while investigating the association between two other variables. See
also control variable, multiple regression.
criterion variable: The variable in a multiple-regression analysis that the researchers
are most interested in understanding or predicting. Also called dependent variable.
predictor variable: A variable in multiple-regression analysis that is used to explain
variance in the criterion variable. Also called independent variable.
Parsimony: The degree to which a theory provides the simplest explanation of some
phenomenon. In the context of investigating a claim, the simplest explanation of a
pattern of data; the best explanation that requires making the fewest exceptions or
qualifications.
Mediator: A variable that helps explain the relationship between two other variables.
Also called mediating variable.
VOCABULARY FOR CHAPTERS 10-12?
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one-group, pretest/posttest design: An experiment in which a researcher recruits one
group of participants; measures them on a pretest; exposes them to a treatment,
intervention, or change; and then measures them on a posttest.
maturation threat: A threat to internal validity that occurs when an observed change in
an experimental group could have emerged more or less spontaneously over time.
history threat: A threat to internal validity that occurs when it is unclear whether a
change in the treatment group is caused by the treatment itself or by an external or
historical factor that affects most members of the group.
regression threat: A threat to internal validity related to regression to the mean, a
phenomenon in which any extreme finding is likely to be closer to its own typical, or
mean, level the next time it is measured (with or without the experimental treatment or
intervention). See also regression to the mean.
regression to the mean: A phenomenon in which an extreme finding is likely to be
closer to its own typical, or mean, level the next time it is measured, because the same
combination of chance factors that made the finding extreme are not present the second
time. See also regression threat.
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attrition threat: In a pretest/posttest, repeated-measures, or quasi-experimental study,
a threat to internal validity that occurs when a systematic type of participant drops out of
the study before it ends.
testing threat: In a repeated-measures experiment or quasi-experiment, a kind of order
effect in which scores change over time just because participants have taken the test
more than once; includes practice effects.
instrumentation threat: A threat to internal validity that occurs when a measuring
instrument changes over time.
selection-history threat: A threat to internal validity in which a historical or seasonal
event systematically affects only the participants in the treatment group or only those in
the comparison group, not both.
selection-attrition threat: A threat to internal validity in which participants are likely to
drop out of either the treatment group or the comparison group, not both.
observer bias: A bias that occurs when observer expectations influence the
interpretation of participant behaviors or the outcome of the study.
demand characteristic: A cue that leads participants to guess a study’s hypotheses or
goals; a threat to internal validity. Also called experimental demand.
double-blind study: A study in which neither the participants nor the researchers who
evaluate them know who is in the treatment group and who is in the comparison group.
masked design: A study design in which the observers are unaware of the experimental
conditions to which participants have been assigned. Also called blind design.
placebo effect: A response or effect that occurs when people receiving an experimental
treatment experience a change only because they believe they are receiving a valid
treatment.
double-blind placebo control study: A study that uses a treatment group and a
placebo group and in which neither the researchers nor the participants know who is in
which group.
null effect: A finding that an independent variable did not make a difference in the
dependent variable; there is no significant covariance between the two. Also called null
result.
ceiling effect: An experimental design problem in which independent variable groups
score almost the same on a dependent variable, such that all scores fall at the high end
of their possible distribution. See also floor effect.
floor effect: An experimental design problem in which independent variable groups
score almost the same on a dependent variable, such that all scores fall at the low end
of their possible distribution. See also ceiling effect.
manipulation check: In an experiment, an extra dependent variable researchers can
include to determine how well a manipulation worked.
Noise: Unsystematic variability among the members of a group in an experiment, which
might be caused by situation noise, individual differences, or measurement error. Also
called error variance, unsystematic variance.
measurement error: The degree to which the recorded measure for a participant on
some variable differs from the true value of the variable for that participant.
Measurement errors may be random, such that scores that are too high and too low
cancel each other out; or they may be systematic, such that most scores are biased too
high or too low.
situation noise: Unrelated events or distractions in the external environment that create
unsystematic variability within groups in an experiment.
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Power: The likelihood that a study will show a statistically significant result when an
independent variable truly has an effect in the population; the probability of not making a
Type II error.
VOCABULARY FOR CHAPTER 13
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Replicable: Describing a study whose results have been reproduced when the study
was repeated, or replicated. Also called reproducible. See also conceptual replication,
direct replication, replication-plus-extension.
direct replication: A replication study in which researchers repeat the original study as
closely as possible to see whether the original effect shows up in the newly collected
data. See also conceptual replication, replication-plus-extension.
conceptual replication: A replication study in which researchers examine the same
research question (the same conceptual variables) but use different procedures for
operationalizing the variables. See also direct replication, replication-plus-extension.
replication-plus-extension: A replication study in which researchers replicate their
original study but add variables or conditions that test additional questions. See also
conceptual replication, direct replication.
scientific literature: A series of related studies, conducted by various researchers, that
have tested similar variables. Also called literature.
meta-analysis: A way of mathematically averaging the effect sizes of all the studies that
have tested the same variables to see what conclusion that whole body of evidence
supports.
file drawer problem: A problem relating to literature reviews and meta-analyses based
only on published literature, which might overestimate the support for a theory because
studies finding null effects are less likely to be published than studies finding significant
results, and are thus less likely to be included in such reviews.
HARKing (hypothesizing after the results are known): A questionable research
practice in which researchers create an after-the-fact hypothesis about an unexpected
research result, making it appear as if they predicted it all along.
p-hacking: A family of questionable data analysis techniques, such as adding
participants after the results are initially analyzed, looking for outliers, or trying new
analyses in order to obtain a p value of just under .05, which can lead to nonreplicable
results.
open science: The practice of sharing one’s data, hypotheses, and materials freely so
others can collaborate, use, and verify the results.
open data: When psychologists provide their full data set on the Internet so other
researchers can reproduce the statistical results or even conduct new analyses on it.
open materials: When psychologists provide their study’s full set of measures and
manipulations on the Internet so others can see the full design or conduct replication
studies.
ecological validity: The extent to which the tasks and manipulations of a study are
similar to real-world contexts; an aspect of external validity. Also called mundane
realism.
theory-testing mode: A researcher’s intent for a study, testing association claims or
causal claims to investigate support for a theory. See also generalization mode.
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generalization mode: The intent of researchers to generalize the findings from the
samples and procedures in their study to other populations or contexts. See also theorytesting mode.
cultural psychology: A subdiscipline of psychology concerned with how cultural
settings shape a person’s thoughts, feelings, and behavior, and how these in turn shape
cultural settings.
field setting: A real-world setting for a research study.
experimental realism: The extent to which a laboratory experiment is designed so that
participants experience authentic emotions, motivations, and behaviors.
Preregistered: A term referring to a study in which, before collecting any data, the
researcher has stated publicly what the study’s outcome is expected to be.
Replicable: Describing a study whose results have been reproduced when the
study was repeated, or replicated. Also called reproducible. See also conceptual
replication, direct replication, replication-plus-extension.
Direct replication: A replication study in which researchers repeat the original
study as closely as possible to see whether the original effect shows up in the
newly collected data. See also conceptual replication, replication-plus-extension.
Conceptual replication: A replication study in which researchers examine the
same research question (the same conceptual variables) but use different
procedures for operationalizing the variables. See also direct replication,
replication-plus-extension.
Replication-plus-extension: A replication study in which researchers replicate
their original study but add variables or conditions that test additional questions.
See also conceptual replication, direct replication.
Scientific literature: A series of related studies, conducted by various
researchers, that have tested similar variables. Also called literature.
Meta-analysis: A way of mathematically averaging the effect sizes of all the
studies that have tested the same variables to see what conclusion that whole
body of evidence supports.
File drawer problem: A problem relating to literature reviews and meta-analyses
based only on published literature, which might overestimate the support for a
theory because studies finding null effects are less likely to be published than
studies finding significant results, and are thus less likely to be included in such
reviews.