Research Methods- Control of variables Flashcards
Extraneous variable (EV) -
Any variable, other than the independent variable (IV), that may have an effect on the dependent variable (DV) if it is not controlled.EVs are essentially nuisance variables that do not vary systematically with the IV.
Confounding variables -
Any variable, other than the IV, that may have affected the DV so we cannot be sure of the true source of changes to the DV. Confounding variables vary systematically with the IV.
Demand characteristics -
Any cue from the researcher or from the research situation that may be interpreted by participants as revealing the purpose of the investigation.
This may lead to a participant changing their behaviour within the research situation.
Investigator effects -
Any effect of the investigator’s behaviour (conscious or unconscious) on the research outcome (the DV). This may include everything from the design of the study to the selection of, and interaction with, participants during the research process.
Randomisation -
The use of chance in order to control for the effects of bias when designing materials and deciding the order of conditions.
Standardisation -
Using exactly the same formalised procedures and instructions for all participants in a research study.
What is the key principle of an experiment regarding variables?
The key principle is that the independent variable (IV) is manipulated to see how it affects the dependent variable (DV), and only the IV should influence the DV.
What are extraneous variables?
Extraneous variables are unwanted variables that might interfere with the IV or DV and should be controlled or removed.
How do extraneous variables differ from confounding variables?
Extraneous variables are nuisance variables that do not vary systematically with the IV, while confounding variables change systematically with the IV and can directly affect the DV.
What is an example of a confounding variable in the energy drink study?
If the first ten participants (water group) are introverted and the next ten (SpeedUpp group) are extroverted, personality becomes a confounding variable.
Why are confounding variables problematic in experiments?
They make it impossible to determine whether changes in the DV are due to the IV or the confounding variable.
What are demand characteristics?
Demand characteristics are cues in the experimental situation that participants use to interpret the study’s aims or the experimenter’s intentions, influencing their behavior.
How can demand characteristics affect participant behavior?
Participants may over-perform to please the experimenter (please-U effect) or under-perform to sabotage the results (screw-U effect), making their behavior unnatural.
How can investigator effects manifest in the energy drink study?
The researcher might unconsciously smile more at energy drink participants, encouraging greater chattiness, or bias participant selection, instructions, or materials.
What are investigator effects?
Investigator effects are unwanted influences of the researcher on the study’s outcome, such as expectancy effects, unconscious cues, or biased design decisions.
What is randomisation, and why is it used in experiments?
Randomisation uses chance to reduce the researcher’s influence on the study’s design, helping to control investigator effects and extraneous/confounding variables.
Provide an example of randomisation in an experiment.
In a memory experiment, the order of words in a list should be randomly generated to avoid experimenter bias in word placement.
What is standardisation in experimental procedures?
Standardisation ensures all participants experience the same environment, information, and procedures, including standardised instructions, to avoid extraneous variables.
Why is standardisation important in experiments?
It ensures consistency across participants, preventing non-standardised changes from acting as extraneous variables.
What is an example of standardisation in the energy drink study?
All participants receive the same instructions and drink quantities (e.g., 300ml of SpeedUpp or water) under the same conditions.
How can participant reactivity be minimized in experiments?
By controlling demand characteristics, using randomisation, and standardising procedures to reduce participants’ ability to interpret or influence the study.
What is the difference between the please-U effect and the screw-U effect?
The please-U effect occurs when participants over-perform to please the experimenter, while the screw-U effect occurs when participants under-perform to sabotage the study.
How can confounding variables be controlled in the energy drink study?
By ensuring extroverted and introverted participants are evenly distributed between the SpeedUpp and water groups.
What is the role of randomisation in controlling investigator effects?
Randomisation reduces the researcher’s influence on the study’s design, such as the order of conditions or participant allocation, minimizing bias.
What is an example of standardised instructions in an experiment?
A script read to all participants explaining the task and procedures in the same way to ensure consistency.
How do extraneous variables “muddy the experimental water”?
They make it harder to detect a clear result by introducing additional variability, though they do not systematically affect the IV or DV.
