Experimental Methods in Psychology

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Experimental Methods in Psychology

• Instructor
• J.P. Garofalo
• Lab Instructor
• Nick Parsons

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What is experimental psychology all about?

• Determine why organisms think and act as they do
• As a discipline, experimental psychology relies
  on scientific procedures

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What is experimental psychology all about?

• Before you start an investigation, you must
• Know something of the construct you plan to
  investigate
• Develop a plan to study the construct
• Experiment considered most powerful scientific
  tool for any discipline

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Making sense of the world

• Ringelmann (1927) with a sensitive gauge measured
  how strongly subjects pulled rope
• Groups of 2 performed at 95 of their capacity
• Groups of 3 performed at 85 of their capacity
• Groups of 8 performed at 49 of their capacity

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Making sense of the world

• Bibb Latane
• People did not work as hard when working in a
  group compared to working alone
• Social Loafing
• Why do people engage in social loafing?
• Diffusion of responsibility
• People working by themselves believe they are
  responsible for completing a task
• However, when in a group, one believes that this
  responsibility diffuses to others

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Making Sense of the World

• Latane and Darley (1970) wanted to test the
  theory of Helping Behavior
• Hypothesis
• The more people who witness an emergency
  situation, the less likely it is that any of them
  will help the victim

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Making Sense of the World

• What is the benefit of such research?
• Its findings may be applied later to solve some
  practical problem
• Williams, Harkins Latane (1981)
• when individual performance could be monitored in
  group situation, people worked just as hard as
  they did when they worked alone

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Purpose of Scientific Psychology

• Curiosity
• Determining why organisms think and behave as
  they do is the ultimate goal of a scientific
  approach to psychology

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Purpose of Scientific Psychology

• Knowledge
• Basic Research
• Glimpses of reality
• Applied Research
• Acquisition of practical knowledge

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Purpose of Scientific Psychology

• Basic Research
• Often precedes applied work
• May be a lag time before basic research findings
  translate into a practical product
• Can be inspired by Applied Research

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Sources of Knowledge

• Aside from Science, how do our beliefs and
  knowledge of the world become fixed?
• Authority
• Parents
• Professors
• Media
• Benefits
• Economic way learning about the world
• Feels safe to have complete faith in authority
  figures
• Disadvantages
• May be wrong

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Sources of Knowledge

• Tenacity
• One refuses to alter acquired knowledge
  regardless of evidence to contrary
• Ex stereotypes
• Benefits
• Allows one to maintain consistent, familiar
  outlook on life, and in turn, will reduce
  psychological distress and uncertainty
• Limitations

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Sources of Knowledge

• A Priori
• Something believed without prior study/
  examination
• Similar to authority except that there is NO one
  particular authority being followed
• Cultural outlook fixes a belief a priori
• Experience fixes a belief a priori
• Advantages and Limitations

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Sources of Knowledge

• Which method is best?
• If we define science as
• A repeatable, self-correcting undertaking that
  seeks to understand phenomena on the basis of
  empirical observation
• Empirical refers to data (observations of the
  world) obtained by systematic observation

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Sources of Knowledge

• Authority, tenacity a priori methods do not
  rely on data obtained by systematic observations
• Did authority base his/her opinion on data?
• Tenacity refuses to consider data
• A priori methods rely on experience or casual
  observation, but this is not systematic

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Scientific Procedure

• Science begins with analysis
• Breaking down complex problem into its elements
• Psychological analysis of emotions, cognitions,
  and behavior involve
• Description
• Prediction
• Explanation

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Scientific Procedure

• These 3 analytic activities correspond to 3 major
  classes of research techniques used in scientific
  psychology
• Description Observation
• Prediction Correlation
• Explanation Experimentation

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Nature of the Scientific Method

• Data
• Empirical Observations
• Theory
• Organization of concepts that permit prediction
  of data
• Induction
• Working from data to theory
• Deduction
• Working from theory to data

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Nature of the Scientific Method

• Popper (1961) a philosopher of science
• Good theories must be fallible
• Empirical predictions must be capable of tests
  that could show them to be false
• Falsifiability view
• Negative evidence is more important than positive
  support
• If a prediction is supported by data, one cannot
  say that the theory is true
• A theory can never be proved, it can only be
  disproved

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Nature of Scientific Reality

• Scientific understanding is tentative
• Incorrect theories are modified
• Modification of theories requires empirical tools
• Baltimore (1997) Questions are not settled
  rather, they are given provisional answers for
  which it is contingent upon the imagination of
  followers to find more illuminating solutions

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Nature of Scientific Reality

• What is a theory?
• Set of related statements that explain a variety
  of occurrences
• The greater the number of occurrences and the
  fewer the statements, the better the theory

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Nature of Scientific Reality

• Evaluating Theories
• Three main criteria
• Parsimony
• Precision
• Testability

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Nature of Scientific Reality

• Theory in psychology performs 2 major functions
• Provides framework for systematic and organized
  display of data
• Allows scientists to generate predictions for
  situations in which no data have been obtained