PSY230H1 Chapter Notes - Chapter 2: Random Assignment, Dependent And Independent Variables, Takers
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Chapter 2: Personality Research Models
The Hypothesis-Testing Approach
•Theory: a general statement about the relationship between constructs/events "
•Some are very broad (e.g. Freud’s psychoanalytic theory used to explain psychological
disorders, as well as why certain jokes are funny) "
•However, personality researchers typically work w/ theories considerably narrower in
application → easier to think of larger theories as collections of more speciﬁc theories that
share certain assumptions"
• Characteristics of a good theory:"
1. Parsimonious "
•Law of parsimony: simplest theory that can explain phenomenon is best "
2. Useful "
•Can generate testable hypotheses → need to be able to lend itself to scientiﬁc
•Theories themselves are never tested; hypotheses are derived from the theories that can
then be tested in research "
•Hypothesis: formal prediction about relationship between two or more variables that’s
logically derived from the theory "
•E.g. why do some people frequently suﬀer from feelings of loneliness, whereas others
rarely feel lonely? → theory: lonely people lack social skills necessary to develop &
maintain satisfying relationships → prediction: consistently lonely people expected to
make fewer attempts to initiate conversations → test"
•Theories are never proved/disproved, only more/less supported by research & more/less
useful to scientists "
•Experimental variables: "
1. Independent variable (treatment variable): determines how groups in experiment are
divided (i.e. when participants are randomly assigned to diﬀ experimental conditions) "
•Found on x-axis "
•Often what’s manipulated by experimenter "
•E.g. amount of a drug each group receives, type of story each group reads, level of
anxiety created in each group (e.g. Group A is told to give a speech in front of a
dozen critical people, while Group B is told to give a speech in front of a few
supportive people & Group C knows nothing about speech) "
2. Dependent variable (outcome variable): measured by the investigator & used to
compare experimental groups "
•Found on y-axis "
•If experiment is well-designed → diﬀerences among groups on the dependent
variable attributed to diﬀ levels of independent variable "
•E.g. returning to anxiety example → hypothesis: people reduce anxiety about
upcoming events by obtaining as much info about the situation as possible →
independent variable: level of anxiety → dependent variable: how many questions
they ask the experimenter about upcoming event "
•Diﬀerence in dependent variable (# questions asked) attributed to diﬀ levels of
independent variable (anxiety) "
•Researchers typically use > 1 independent variable (e.g. randomly assign participants to
anxiety/no-anxiety group → identify shy & non-shy w/in each of these groups) "
•Interaction: how one independent variable aﬀects the dependent variable depends on the
other independent variable "
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