Research Methods in Psychology Vocabulary

Aim

The overarching purpose of a research study.

Independent Variable (IV)

The factor in an experiment that is manipulated or changed by the researcher to test its effects.

Dependent Variable (DV)

The variable measured by the researcher to assess the effect of the independent variable.

Experimental Condition

A level or group in an experiment in which the independent variable is present or applied.

Control Condition

A level or group in an experiment in which the independent variable is absent, used as a baseline for comparison.

Null Hypothesis

A statement predicting that there is no relationship or difference between the variables being studied, and that any observed difference is due to chance.

Nondirectional Hypothesis

A two-tailed hypothesis predicting that the independent variable will affect the dependent variable, without specifying the direction of the effect.

Directional Hypothesis

A one-tailed hypothesis predicting that the independent variable will affect the dependent variable in a specific direction.

Laboratory Experiment

An experiment conducted in an artificial setting manipulated by the researcher, characterized by high control over environment and variables.

Field Experiment

An experiment carried out in the participants' normal, real-world environment, where the researcher still manipulates the independent variable.

Natural Experiment

A study examining the effect of a naturally occurring change or existing difference where the independent variable cannot be manipulated by the researcher.

Quasi Experiment

An experiment in a lab setting where the independent variable is naturally occurring (such as gender or time of day) and participants cannot be randomly assigned to conditions.

Population

The entire group of individuals sharing specific characteristics from which a sample can be drawn for a study.

Sample

A group of participants selected from a target population to represent that population in a study.

Opportunity Sampling

A sampling technique in which participants are selected simply because they are available and present at the place and time of the study.

Volunteer Sampling

A sampling technique where participants self-select by actively responding to an invitation, advertisement, or email.

Random Sampling

A sampling technique in which every member of the target population has an equal chance of being selected.

Participant Variable

An extraneous variable related to individual characteristics of participants, such as age, intelligence, or personality.

Order Effect

A change in participant performance across conditions in a repeated measures design that results from the sequence of tasks rather than the independent variable.

Practice Effect

An order effect where participant performance improves across conditions due to familiarity or learning from repeating the task.

Fatigue Effect

An order effect where participant performance declines across conditions because participants become tired or bored.

Demand Characteristics

Cues or features in an experimental situation that reveal the study's aim, leading participants to unconsciously alter their behavior.

Situational Variables

Environmental factors, such as noise, weather, or distractions, that can influence participant behavior during an experiment.

Independent Measures Design

An experimental design in which a separate group of participants is used for each condition of the independent variable.

Repeated Measures Design

An experimental design in which the same group of participants takes part in all conditions of the study.

Matched Pairs Design

An experimental design in which participants are paired based on shared, relevant variables and then assigned to different conditions.

Standardization

Keeping experimental procedures and instructions identical for all participants to ensure consistency and increase reliability.

Counterbalancing

A method used to control order effects in a repeated