Psych Chapter 0

experimental psychology

The study of behavior and thinking using the experimental method.

psychology

The science of behavior and mental processes.

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).

critical thinking

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

hypothesis

A testable prediction, often implied by a theory.

operational definition

A carefully worded statement of the exact procedures (operations) used in a research study.

replication

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

case study

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

survey

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

population

All the cases in a group being studied, from which samples may be drawn.

random sample

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

naturalistic observation

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

correlation

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

correlation coefficient

A statistical index of the relationship between two things (from -1 to +1).

scatterplot

A graphed cluster of dots, each of which represents the values of two variables.

experiment

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

random assignment

Assigning participants to experimental and control groups by chance, minimizing preexisting differences between groups.

double-blind procedure

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

placebo effect

Experimental results caused by expectations alone, any effect on behavior caused by administering an inert substance which the recipient assumes is active.

experimental group

The group exposed to the treatment in an experiment.

control group

The group not exposed to the treatment, serving as a comparison for evaluating the effect of treatment.

independent variable

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

confounding variable

A factor other than the independent variable that might produce an effect in an experiment.

dependent variable

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

mode

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

mean

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

median

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

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 (normal distribution)

A symmetrical, bell-shaped curve that describes the distribution of many types of data.

informed consent

An ethical principle requiring research participants be told enough to enable them to choose whether to participate.

debriefing

The post-experimental explanation of a study, including its purpose and any deceptions, to its participants.

sampling bias

A flawed sampling process that produces an unrepresentative sample.

regression toward the mean

The tendency for extreme scores to fall back toward the average.

skewed distribution

A representation of scores that lack symmetry around their average value.

statistical significance

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

bimodal distribution

A frequency distribution having two different values that are heavily populated with cases.

confederate

An aide of the experimenter who poses as a participant, but whose behavior is rehearsed prior to the experiment.

confidentiality

A principle requiring researchers to limit the disclosure of participants' identity and any unique data collected.

confirmation bias

A tendency to search for information that supports our preconceptions and to ignore or distort contradictory evidence.

convenience sampling

A method for selecting a sample that is neither random nor systematic but rather based on availability.

cultural norm

A societal rule or standard that delineates accepted behavior within a culture.

deception

Any distortion of or withholding of fact with the purpose of misleading others.

descriptive statistics

Statistical techniques used to summarize and describe the characteristics of a dataset.

directionality problem

In correlational research, the situation where it is unknown which variable is the cause and which is the effect.

effect size

A measure of the magnitude or meaningfulness of a relationship between two variables.

ethical guidelines

Rules of acceptable conduct that members of a given profession are expected to follow.

experimenter bias

Occurs when a researcher's expectations or preferences influence the results of a study.

falsifiable/falsifiability

The principle that for a hypothesis or theory to be scientific, it must be possible to conceive of evidence that would prove it false.

generalizability

Degree to which a study's findings based on a sample apply to the entire population.

inferential statistics

Statistical techniques used to make inferences or predictions about a population based on sample data.

informed assent

The agreement of someone not able to give legal consent to participate in the activity.

Institutional Review Board (IRB)

A committee at each college/university that reviews every experiment for ethics and methodology.

meta-analysis

A procedure for statistically combining the results of many different research studies.

negative correlation

A relationship where the value of one variable increases as the value of the other decreases.

negative skew

The degree to which scores are asymmetrically distributed with a majority toward the high end.

non-experimental

Research where the investigator cannot manipulate the independent variable and cannot limit the influence of extraneous variables.

participant bias

A tendency for research participants to respond in a certain way due to beliefs about the study.

peer review

The evaluation of scientific or academic work by others in the same field to ensure its quality.

placebo group

Any group that receives an inert treatment to compare its effects against the treatment of interest.

positive correlation

A relationship between two variables in which both rise and fall together.

positive skew

The degree to which scores are asymmetrically distributed with a majority toward the low end.

protection from harm

Steps taken to avoid and minimize adverse effects for research participants.

qualitative research methods

Research focused on gathering and analyzing non-numerical data to understand meanings and experiences.

quantitative research methods

Research that focuses on gathering and analyzing numerical data to understand relationships or trends.

random sampling

A portion that fairly represents a population with equal chances of inclusion.

random assignment

Assigning participants to groups by chance to minimize preexisting differences.

reliability

The ability of a test to yield similar scores for the same individual over repeated testings.

replication

Repeating a research study to see if the findings extend to other participants.

representative sample

The unbiased selection of study units from a larger population.

sample

A relatively small proportion of people chosen in a study to represent the whole.

self-report bias

Inaccuracies in survey responses due to social desirability or misunderstanding.

single-blind study

Research design where participants do not know whether they are in the experimental or control group.

skewed distribution

A distribution where scores cluster toward one end of the range.

social desirability bias

A tendency to give socially approved answers about oneself.

survey

A technique to ascertain self-reported attitudes or behaviors of a group.

third variable problem

An undiscovered variable that may be the true cause in a relationship between two variables.

validity

The ability of a test to measure what it is intended to measure.

variation

The square of the standard deviation, indicating how spread out the data are.

wording effects

When specific words used in questions affect how respondents answer.

effect size

Measures of the magnitude or meaningfulness of a relationship between two variables.