extraneous varibles Flashcards
(13 cards)
Extraneous Variables
are all variables, which are not the independent variable, but could affect the results of the experiment.
Situational Variables
Aspects of the environment that might affect the participants behavior.
Must be controlled so each participant is exposed to the same conditions.
Examples, temperature, lighting etc.
If a good research plan is used this should lower/eliminate these variables.
controls for situational
The most effective way of controlling most situational variables is to hold them constant throughout the experiment.
Test subjects in the same conditions and situation (except if the IV permits).
Good planning will help eliminate situational variables
To control order effect
Counterbalancing
Changing the order in which the treatments or tasks are performed.
Participant Variables
How each participant is different from each other. And how this may impact results.
For example, the participants mood, mental health levels, concentration levels or nerves.
For example, having someone perform a memory test. The participants turns out to be tired or have low concentration levels because they have ADHD.
minimising participant varibles
The experimental design could help to minimize/eliminate these variables.
Sampling procedures can also help overcome these variables.
Controls
Random Sampling -ensures the sample is representative of the population.
Random Allocation - a large number of participants- reasonable to assume each group will end up w/ same spread of participants.
Appropriate Experimental Design - depending on the design will depend on the EV’s being controlled.
Within Subjects –
effective for controlling participant variables.
Between Subjects –
also good for participant variables (with a large sample size). Uses random allocation.
Demand Characteristics
Demand characteristics are cues in an experiment that may influence or bias a participant’s response, thereby distorting the results.
A cue is some kind of stimulus, event, or object that serves to guide behaviour.
A participant may use cues such as random noises, changes in lighting
Placebo Effect
The placebo effect occurs when there is a change in a participant’s behaviour due to their belief that they are receiving some kind of experimental treatment and they respond in accordance with that belief, rather than to the effect of the IV.
Control
Single-Blind Procedure
Participants are unaware (blind to) the experimental condition they are in.
For example, they may know what the experiment is about, but they don’t know whether they are in an experimental or control group.
Placebo
Use of a placebo “fake treatment.”
Double-Blind Procedure
Both the participants and experimenter are unaware of which condition participants are allocated.
Experimenter Variables
Variables surrounding the influence of the experimenter.
-may accidently influence how the participant should behave.
-providing the participant unintentional clues about what the experiment is about- how they should act while completing it.
E.g age, gender or nationality of the experimenter could influence the behaviour of the participant.
- variables can be prevented by using a double-blind procedure and standard instructions
Controls for experiementer variables
Double-Blind Procedure
Both the participants and experimenter are unaware of which condition participants are allocated.
Standardised Instructions
Instructions given to participants must be the same for all groups within the experiment.
Confounding Variable
is a variable other than the IV that has influenced the DV.
It is important to remember that not all CVs are EVs. However, if an EV is left uncontrolled it MAY turn into a CV.
