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Chapter 2: The Ways and Means of Psychology
-the scientific method permits us to discover the nature and causes of behaviour
The Scientific Method of Psychology
-scientific method ±a set of rules that dictate the general procedure a scientist must follow in his research
-these rules are based on logic and common sense + devised by philosophers who were attempting to
determine how we could understand reality
-psychologists conduct 3 major types of scientific research which occur in a progressive sequence
x 1) Naturalistic observation ±the observation of the behaviour of people or other animals in their
natural environments; provide the foundations of the biological and social sciences
x Clinical observation ±the observation of t he behaviour of people who are undergoing a
diagnosis or treatment for a psychological condition
x Least formal types set by few rules
x 2) Correlational studies ±observed in nature but involves more formal measurement of
x The examination of relations between two or more measurements
x 3) Experiments ±a study in which the researcher changes the value of an independent variable
and observes whether this manipulation affects the value of the dependent variable
x Only experiments can positively identify the casual relations among events
-the scientific method involves 5 steps:
1. Identify the problem and formulate hypothetical cause-and-effect relations among variables
-involves finding variables and describing the relations among them
2. Design the experiment
-manipulation of independent variables and the observation of dependent variables
-each variable must be operationally defined and the independent variable must be controlled
3. Perform the experiment
4. Evaluate the hypothesis by examining data from the study
-involves mathematical procedures used to determine whether an observed effect is statistically
5. Communicate the results
Identifying the Problem: Getting an Idea for Research
-a statement designed to be tested by an experiment, that expresses a cause-and-effect relationship
between two or more events
-a set of statements that describes and explains known facts, proposes relations among variables, and
make new predictions
-elaborate form of hypothesis
-many psychologists are directed at marking a particular theory stronger
Naturalistic and Clinical Observations as Sources of Hypotheses and Theories
-naturalists are people who observe animals in their natural environment disturbing them as little as
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-clinical psychologists can often observe important patterns of behaviour
-often report the results of their observations in detailed descriptions as case studies
-does not remain in the background
-sometimes psychologists do interfere with a situation in a natural or clinical setting
-naturalists may conduct a survey study, while a clinical psychologist may manipulate the treatment given
to a patient but this would no longer be an observational study but rather an experiment
Designing an Experiment
-variables ±things that can vary in value
-scientists either manipulate or measure the values of variables
-experimental group vs. control group
-the variable that we manipulate is the independent variable, the one we measure is the dependent variable
-a hypothesis describes how the value of a dependent variable depends on the value of an independent
-independent and dependent variables are categories into which various behaviours are classified
-nominal fallacy ±the false belief that one has explained the causes of a phenomenon
-the task of a psychologist is to determine which of the many events that occurred before a particular
behaviour caused that behaviour to happen
Operational Definitions
-operational definition ±the definition of a variable in terms of the operations the researcher performs to
measure or manipulate it
-independent variables and dependent variables are defined in terms of the operations a researcher
performs to set their values or to measure them
-the validity of operational definition refers to how DSSURSULDWHWKH\DUHIRUWHVWLQJWKHUHVHDUFKHV
hypothesis ±how accurately they represent the variables whose values have been manipulated or
Control of Independent Variables
-if a TV program was used as a manipulation of noise, we would inadvertently cause confounding of
variable ±inadvertent simultaneous manipulation of more than one variable; the results of the experiment
involving confounded variables permit no valid conclusions about cause and effect
-the effect of the manipulation on reading could be due to either noise or content
-based on bird experiment: this phenomenon is called habituation ±when a stimulus is presented
¾ We do not know whether the decrease in signs of alarm occurred b/c the stimuli looked less and
less like the predator or because the birds became habituated to the stimuli
¾ Counterbalancing ±a systematic variation of a conditions in an experiment, such as the order of
stimuli, so t hat different participants encounter them in different orders; prevents confounding of
independent variable with time-dependent processes such as habituation or fatigue
Performing an Experiment
Reliability of Measurements
-a procedure described by an operational definition that produces consistent and precise results under
consistent conditions has high reliability ±the repeatability of measurement
-achieving reliability is much easier than achieving validity
-conditions throughout the experiment should always be as consistent as possible such as the same
instructions given and all equipment should be in good working order
-the degree of subjectivity in taking a measurement also affects reliability
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