Experimental Research in Psychology

Overview of Experimental Research

• Experimental research is one of the three primary types of research in psychology.

  • Other types include:

    • Descriptive research

    • Correlational research

  • Both descriptive and correlational research do not provide insights into cause and effect.

• The essential purpose of experimental research is to determine if one variable (variable X) causes a change in another variable (variable Y).

Purpose of Experimental Research

• Only experimental research provides the knowledge of causal relationships.

• It answers questions like:

  • Did something cause another event to take place?

• Experimental research allows researchers to observe and understand the impact of varying one or more variables on others.

Laboratory Setting of Experimental Research

• Experimental research is conducted in a laboratory setting.

  • This environment allows researchers to:

    • Control all variables that might affect the outcome.

    • Use controlled settings, including cameras and two-way mirrors, to ensure that external factors do not influence the experiment.

Key Concepts in Experimental Research

• Manipulation:

  • In the context of experimental research, "manipulation" refers to altering or changing a specific variable to observe the effects on another variable.

  • This term is favored in AP Psychology and plays a crucial role in how studies are conducted.

• The goal is to understand how this manipulation of a variable impacts other variables.

Types of Experimental Studies

• Within the realm of experimental research, there are two primary study designs:

  • Single Blind Study:

    • The experimenter knows the details of the study, including whether participants receive a real or placebo treatment, while the participants do not have this knowledge.

    • Example Scenario:

      • In a drug study, the experimenter may know what drug is being given to a participant, whereas the participant is unaware.

      • This design controls for participant bias but could still lead to experimenter bias as the experimenter’s knowledge may inadvertently affect their interactions with participants.

  • Double Blind Study:

    • Both the experimenter and the participant are unaware of which treatment the participant is receiving.

    • This design is implemented to eliminate both participant and experimenter bias.

    • Typically involves assigning a third party to manage treatment assignments in a blinded manner.

    • Example Scenario:

      • In a double blind drug trial, neither the participant nor the experimenter knows if the participant is getting the actual drug or a placebo.

      • The experimenter might simply receive an envelope stating, "Subject number six gets pill A," with no further details about the pill.

Importance of Blinding in Experimental Research

• Blinding (single or double) is crucial to prevent biases that could skew results.

  • Single Blind Issues:

    • The possibility of experimenter bias still exists since the experimenter has knowledge of the treatment group.

  • Double Blind Advantages:

    • Ensures that neither participants nor experimenters influence the outcomes or interpretations.

Summary of Experimental Research Methodology

• Experimental research is fundamentally defined by its manipulation of variables in a controlled environment to observe cause and effect relationships.

• Researchers implement either single blind or double blind methods to maintain objectivity and rigor in their findings.