Extraneous variables & Control of them

• Participant variables


  characteristics of participants controlled by random allocation
• Situational variables

  features of the environment that can affect the results controlled by standardisation
• Order Effects


  same group of participants tested in all conditions of IV performance of second condition - same group of participants tested in all conditions of IV performance of second condition is affected - controlled by counterbalancing (abba)
• Demand Characteristics


  cues/signals enable participants to guess aim of experiment (please-U/Screw-U) - controlled by using independent groups design or single blind design
• Investigator Effects


  effects the researcher has on the research outcome and selection of participants and design - controlled by double blind design and randomization
• What are extraneous variables?

  Extraneous variables are variables that can affect the outcome of an experiment but are not the independent variable.
• What are the types of extraneous variables?

  • Participant variables
  • Situational variables
  • Order effects
  • Demand characteristics
  • Investigator effects
• Why should extraneous variables be controlled?

  To prevent them from becoming confounding variables that affect the validity of the experiment.
• What are participant variables?

  Participant variables are characteristics of participants that can affect the outcome of an experiment.
• Give examples of participant variables.

  Age, IQ, gender, personality, and experience are all examples of participant variables.
• When do participant variables act as extraneous variables?

  They act as extraneous variables when they are relevant to the dependent variable being measured.
• In which experimental design do participant variables act as extraneous variables?

  Participant variables act as extraneous variables in an independent groups experimental design.
• How can random allocation control participant variables?

  Random allocation assigns participants randomly to different conditions, minimizing the impact of participant characteristics.
• What is one method of random allocation?

  The lottery method, where participants are assigned numbers and drawn from a hat.
• What is another method of random allocation?

  A random number generator can be used to assign participants to conditions.
• What is a matched pairs design?

  A matched pairs design involves pairing participants based on a relevant variable and testing each member in different conditions.
• How does a matched pairs design control participant variables?

  It reduces the likelihood of participant variables acting as extraneous variables by matching them across conditions.
• What are situational variables?

  Situational variables are features of the environment that can affect the results of an experiment.
• Give examples of situational variables.

  Temperature, time of day, and noise level are examples of situational variables.
• When do situational variables act as extraneous variables?

  They act as extraneous variables when they are relevant to the dependent variable being measured.
• How can situational variables be controlled?

  Standardisation can be used to keep procedures and instructions the same for all participants.
• What are order effects?

  Order effects are changes in participants' performance due to the order in which conditions are experienced.
• When do order effects act as extraneous variables?

  Order effects act as extraneous variables in a repeated measures experimental design.
• How can order effects be controlled?

  Counterbalancing can be used to control order effects by varying the order of conditions for participants.
• What is counterbalancing?

  Counterbalancing is when half of the participants experience condition A followed by condition B, and the other half experience condition B followed by condition A.
• How does counterbalancing help in experiments?

  It helps cancel out any order effects that may influence the results.
• What are demand characteristics?

  Demand characteristics are cues that enable participants to guess the aim of the experiment.
• How do demand characteristics affect participants' behavior?

  They may cause participants to change their behavior to meet perceived expectations.
• What is the 'please-U effect'?

  The 'please-U effect' occurs when participants act in a way they think will please the researcher.
• What is the 'screw-U effect'?

  The 'screw-U effect' occurs when participants deliberately act in a way to sabotage the results of the experiment.
• When are demand characteristics more likely to be a problem?

  They are more likely to be a problem in a repeated measures design.
• How can demand characteristics be controlled?

  Using an independent groups design can help reduce demand characteristics.
• What is a single-blind design?

  A single-blind design is when participants are unaware of the research aims and which condition they are experiencing.
• How does a single-blind design help in experiments?

  It reduces the risk of demand characteristics affecting participants' behavior.
• What are investigator effects?

  Investigator effects are influences of the researcher’s characteristics or behavior on the research outcome.
• Give examples of investigator effects.

  The researcher’s appearance, communication style, and selection of participants can all influence the research outcome.
• Why are investigator effects difficult to control?

  Because they can arise from various aspects of the researcher's behavior and characteristics.
• What is a double-blind design?

  A double-blind design is when both the participant and the researcher are unaware of the research aims and conditions.
• How does a double-blind design help in experiments?

  It reduces the risk of both demand characteristics and investigator effects influencing the results.
• How can randomisation reduce investigator effects?

  Randomisation uses chance to determine aspects of the investigation, minimizing the researcher's influence.