THE WAYS AND MEANS OF PSYCHOLOGY
Scientific method: A set of rules that governs the collection and analysis of data gained through observational
studies or experiments.
Naturalistic observation: The observation of the behaviour of people or other animals in their natural
Clinical observation: The observation of the behaviour of people who are undergoing diagnosis or treatment.
Correlation studies: The examination of relations between two or more measurements of behaviour or other
characteristics of people or other animals.
Experiment: A study in which the researcher changes the value of an independent variable and observes
whether this manipulation affects the value of a dependent variable. Only experiments can confirm the
existence of cause-and-effect relations among variables.
5 steps for scientific method
1. Identify the problem and formulate hypothetical cause and effect relationship among variables
2. Design the experiment
3. Perform the experiments
4. Evaluate the hypothesis by examining the data from the study
5. Communicate the results
Hypothesis: A statement, usually designed to be tested by an experiment that tentatively expresses a cause-
and-effect relationship between two or more events.
Theory: A set of statements designed to explain a set of phenomena; more encompassing than a hypothesis.
Case studies: A detailed description of an individual’s behaviour during the course of clinical treatment or
Survey study: A study of people s responses to standardized questions. variable Anything capable of assuming
any of several values.
Manipulation: Setting the values of an independent variable in an experiment to see whether the value of
another variable is affected.
Experimental group: A group of participants in an experiment, the members of which are exposed to a
particular value of the independent variable, which has been manipulated by the researcher.
Control group: A comparison group used in an experiment, the members of which are exposed to the
naturally occurring or zero value of the independent variable.
Independent variable: The variable that is manipulated in an experiment as a means of determining cause-
Dependent variable: The variable that is measured in an experiment.
Nominal fallacy: The false belief that one has explained the causes of a phenomenon by identifying and
naming it; for example, believing that one has explained lazy behaviour by attributing it to laziness.
Operational definition: The definition of a variable in terms of the operations the researcher performs to
measure or manipulate it.
Validity: The degree to which the operational definition of a variable accurately reflects the variable it is
designed to measure or manipulate.
Confounding of variables: Inadvertent simultaneous manipulation of more than one variable. The results of an
experiment involving confounded variables permit no valid conclusions about cause and effect.
Counterbalancing: A systematic variation of conditions in an experiment, such as the order of presentation of
stimuli, so that different participants encounter them in different orders; prevents confounding of
independent variables with time-dependent processes such as habituation or fatigue.
Reliability: The repeatability of a measurement; the likelihood that if the measurement was made again it
would yield the same value. Interrater reliability: The degree to which two or more independent observers agree in their ratings of
another organism’s behaviour.
Random assignment: Procedure in which each participant has an equally likely chance of being assigned to
any of the conditions or groups of an experiment
Placebo: An inert substance that cannot be distinguished in appearance from a real medication; used as the
control substance in a single-blind or double-blind experiment.
Single-blind study: An experiment in which the researcher but not the participant knows the value of the
Double-blind study: An experiment in which neither the pa