CONTROL OF VARIABLES Flashcards
In any experiment, there will always be a number of unwanted factors that can potentially affect the relationship between the IV and the DV. Which two variables are students required to know about for the exam?
- Extraneous variables (EV)
- Confounding variables
What are extraneous variables (EV)?
Any variable, other than the IV, that may have an effect on the DV if it is not controlled. Extraneous variables are essentially nuisance variables that do not vary systematically with the IV.
Are extraneous variables difficult or straightforward to control?
Many extraneous variables are straightforward to control (e.g. lighting in a lab).
Do extraneous variables confound the findings of a study?
Extraneous variables do not confound the findings of a study. They may just make it harder to detect a result.
Extraneous variables can be sub-divided into two categories. What are these two categories?
- Participant variables
- Situational variables
Extraneous variables can be sub-divided into participant variables and situational variables. List examples of participant variables.
- Personality
- Age
- Gender
- Intelligence
- Motivation
- Concentration
Extraneous variables can be sub-divided into participant variables and situational variables. List examples of situational variables.
- Noise
- Time of day
- Temperature
- Instructions
- Weather
What are 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.
Provide one example of a confounding variable and explain how this can be applied to the energy drink experiment.
Personality is an example of a confounding variable. For example, in the energy drink experiment there are 20 participants in total. The first 10 who arrive are assigned to the water condition. It happens that these first 10 participants were introverted individuals. The next 10 participants are extroverts and they are assigned to the SpeedUpp condition. This means the psychologist has ended up with a second unintended IV: personality. Psychologists can therefore not be sure that the Speedupp group were chatter because of the drink (it could be because they were extraverts).
What are demand characteristics?
Demand characteristics refer to any cue from the researcher or from the research situation that may be interpreted by the participants as revealing the purpose of the investigation. This may lead to a participant changing their behaviour within the research situation.
How could demand characteristics negatively impact the research findings?
Participants are not passive within experiments and are likely to be spending much of their time making sense of the new situation. As such, participant reactivity is a significant extraneous variable in experimental research and one that is very difficult to control. This makes it difficult to conclude that changes in the DV were the direct effect of the IV.
Participants may look for cues to tell them how they should behave in a situation. Which two ‘effects’ does this result in?
The ‘please-U effect’:
The participant may act in a way that they think is expected and over-perform to please the experimenter.
The ‘screw-U effect’:
The participant may deliberately under-person to sabotage the results of the study.
How does the ‘please-U effect’ and the ‘screw-U effect’ negatively impact the findings of a study?
These effects cause participant behaviour to stop being natural. They are therefore examples of extraneous variables that may affect the DV.
What are investigator effects?
Any effect of the investigator’s behaviour (conscious or unconscious) on the DV. This may include everything from the design of the study to the selection of, and interaction with, participants during the research process.
How can investigator effects be applied to the energy drink experiment?
If is possible that during the energy drink study, psychologists smiled more during their interactions with some participants than others. Given that they were expecting the energy drink group to speak more than the water group, they may have encouraged a greater level of chattiness from the energy drink participants.
