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Chapter 2

PSYA01H3 Chapter Notes - Chapter 2: Operational Definition, Central Tendency, Habituation

Course Code
Steve Joordens

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CHAPTER 2 The Ways and Means of Psychology
The Scientific Method in Psychology
The scientific method consists of a set of rules that dictate the general procedure a
scientist must follow in his or her research (a set of rules that governs the collection and
analysis of data gained through observational studies or experiments); these rules are not
arbitrary; they are based on logic and common sense
Psychologists conduct three major types of scientific research:
- The first type includes naturalistic observation (the observation of the
behaviour of people or other animals in their natural environment) and clinical
observation (the observation of the behaviour of people who are undergoing
diagnosis or treatment for a psychological condition)
o These methods are the least formal and are constrained by the fewest
o Naturalistic observations provide the foundations of the biological
and social sciences
- The second type, correlational studies, is observational in nature but involves
more formal measurement of environmental events, of individuals’ physical
and social characteristics, and of their behaviour (correlational study is the
examination of relations between two or more measurements of behaviour or
other characteristics of people or other animals)
- Finally, experiments go beyond mere measurement; a psychologist performing
an experiment makes things happen and observes the results (an experiment is 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); only experiments can positively identify the causal relations among
The following five steps summarizes the rules of the scientific method that apply to
experiments the form of scientific research that identifies cause-and-effect relations
1. Identify the problem and formulate hypothetical cause-and-effect relations among
variables this step involves identifying variables (particular behaviours and
particular environmental and physiological events) and describing the relations
among them in general terms
2. Design the experiment experiments involve the manipulation of independent
variables and the observation of dependent variables; each variable must be
operationally defined, and the independent variable must be controlled so that only it,
and no other variable, is responsible for any changes in the dependent variable
3. Perform the experiment
4. Evaluate the hypothesis by examining the data from the study


5. Communicate the results
Identifying the Problem: Getting an Idea for Research
Most research occurs in institutional settings such as universities, where scientists,
students, and technicians are all involved in the effort; long-term projects require
financial support
Psychological research in Canada has historically been supported by the three major
research-funding agencies of the Canadian government: the Natural Sciences and
Engineering Research Council, the Social Sciences and Humanities Research Council,
and the Canadian Institutes of Health Research
In this environment of competition and rigorous evaluation, a successful scientist needs
to have good ideas; where do they come from?
A hypothesis is the starting point of any study; a hypothesis is a statement, usually
designed to be tested by an experiment, that tentatively expresses a cause-and-effect
relationship between two or more events
A theory is a set of statements that describes and explains known facts, proposes
relations among variables, and makes new predictions; it is designed to explain a set of
phenomena; more encompassing than a hypothesis
A good theory is also one that generates testable hypotheses hypotheses that can
potentially be supported or proved wrong by scientific research
Naturalistic and Clinical Observations as Sources of Hypotheses and Theories
Naturalists are people who carefully observe animals in their natural environment,
disturbing them as little as possible; naturalistic observations, then, are what naturalists
see and record
All sciences physical, biological, and social begin with simple observation
Psychologists who are also naturalists apply observational procedures to questions of
behaviour; the important feature of naturalistic observations is that the observer remains
in the background, trying not to interfere with the people (or animals) being observed
Clinical observations are different; in the course of diagnosis or treatment, clinical
psychologists can often observe important patterns of behaviour; they often report the
results of their observations in detailed descriptions known as case studies (a detailed
description of an individual’s behaviour during the course of clinical treatment or
diagnosis); as with naturalistic observations, these could form the basis of hypotheses
about the causes of behaviour


- Unlike a naturalist, however, a clinical psychologist most likely does not remain
in the background, because the object of therapy is to change the patient’s
behaviour and to solve problems; the psychologist is ethically constrained to
engage in activities designed to benefit the patient; he or she cannot arbitrarily
withhold some treatment or apply another just for the sake of new observations;
so the clinician cannot interfere with the treatment regime prescribed for the
In a survey study, researchers may ask people specially designed and controlled
questions, perhaps about their beliefs, opinions, or attitudes; survey studies are designed
to elicit a special kind of behaviour: answers to the questions; the observations, then, are
usually descriptions of the classes of responses to these questions
Designing an Experiment
Although naturalistic or clinical observations enable a psychologist to classify behaviours
into categories and provide hypothetical explanations for them, only an experiment can
determine whether these explanations are correct
Scientists refer to components as variables: things that can vary in value, or anything
capable of assuming any of several values; thus, temperature is a variable, and so is
Scientists either manipulate or measure the values of variables; manipulate literally
means “to handle”; because of abuses in the history of human research, the term
manipulation is sometimes incorrectly understood to mean something that researchers do
to participants; psychologists use the word, however, to describe setting the values of a
variable in order to examine that variable’s effect on another variable; the results of
experimental manipulations and measurements of variables help us evaluate hypotheses
To test the visual expectation hypothesis with an experiment, we would assemble two
groups of volunteers to serve as participants; the experimental group is 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; the control
group is a comparison group used in an experiment, the members of which are exposed
to the naturally occurring or zero value of the independent variable
The variable that we manipulate is called the independent variable (the variable that is
manipulated in an experiment as a means of determining cause-and-effect relations); the
variable that we measure is the dependent variable (the variable that is measured in an
experiment); an easy way to keep the names of these variables straight is to remember
that a hypothesis describes how the value of a dependent variable depends on the value of
an independent variable
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