Experimental Psychology and the Scientific Method

Experimental Psychology and the Scientific Method

• Psychology is the science of behavior. Psychologists use scientific evidence gathered through research.
• Science has two meanings: content (facts or knowledge) and process (methods for gathering data, identifying relationships, and offering explanations).

Topics Covered

• Need for scientific methodology
• Characteristics of modern science
• Objectives of psychological science
• Scientific method: tools of psychological science
• Scientific explanation in psychological science
• From pseudoscience to psychological science

Objectives

• Understand why scientific methods are used instead of common sense to explain behavior
• Understand the principles of the scientific method
• Learn the basic tools of psychological research
• Understand how "cause-and-effect" is determined through experimentation.

Psychology as a Science

• Psychology is the science of behavior, established on accumulated scientific evidence through research.
• The word "science" comes from the Latin word scientia, meaning knowledge
• Modern usage of "science" encompasses both the content (facts and knowledge) and the process (methods used to gather information).

The Need for Scientific Methodology

• Everyday, nonscientific data gathering shapes expectations and beliefs, influencing behavior; this is called "common sense psychology."
• Nonscientific data sources (friends, family, media, etc.) may not be accurate and can be influenced by biases.
• Confirmation bias is the tendency to favor information that confirms existing beliefs, while ignoring contradictory evidence.
• The belief that the full moon influences behavior is an example of this bias.

Nonscientific Sources of Data

• Sources that seem credible can present inaccurate information about behavior.
• Individuals with high status, perceived expertise, or confidence are more persuasive than others are perceived to be.

The Power of Negative Thinking

• Friday the 13th is often viewed as an unlucky day, but research shows no evidence of any negative influence on human behavior.
• The high number of car accident emergency room visits on Friday the 13th is more the result of increased driver anxiety than on any mystical ill omen.
• Studies of driver anxiety and increased risk-taking are relevant in an experimental context.

Nonscientific Inference

• People frequently overestimate the accuracy of their intuitive explanations of behavior, a phenomenon known as the 'overconfidence bias.'
• Overconfidence is not the same as good judgment.
• The accuracy of inferential predictions about others improves when people know them better, but good judgment does not always follow this pattern.

The Scientific Method: Tools of Psychological Science

• Observation is a carefully systematic method for recording events. Only observable events can be studied scientifically.
• Measurement is the assignment of numerical values to characteristics of events under observation.
• Experimentation is an approach for testing hypotheses. A controlled setting allows researchers to manipulate aspects of the environment to produce a specific behavior and test whether or not that behavior predictably follows from the manipulated aspects.

Scientific Explanation in Psychological Science

• Identifying antecedent conditions: Antecedent conditions are conditions preceding the events that need to be explained.

• Comparing treatment conditions: comparing different treatment conditions allows for a scientific assessment

• Experimentation is a controlled process to verify or falsify hypotheses, involving manipulation of variables and measuring their effect.

  • Two major experimental methodologies are used -between subjects design (different subjects receive different treatments)
    • within subjects design (the same subjects receive all treatments)

• Establishing cause and effect: within an experimental context, cause and effect is established reliably through careful observation. Cause is always prior to effect.

From Pseudoscience to Psychological Science

• Psychology as an experimental discipline emerged in Germany in the late 1800s.
• Wilhelm Wundt is credited as the “father of experimental psychology.”
• The scientific method is used in psychology to test hypotheses regarding human sensory and perceptual tasks as well as psychological concepts.
• Historical methodologies (e.g., phrenology, mesmerism, spiritualism) were employed that have not held up to scientific scrutiny.

Objectives of Psychological Science

• Description, prediction, explanation, and control are the four major objectives of psychological research.