Control, Demand Characterisitcs & Investigator Effects Flashcards
What are extraneous variables?
Extraneous variables are any variables other than the independent variable (IV) that might affect the dependent variable (DV) and thus affect the results.
What following measures can control / eliminate extraneous variables?
+ Random allocation
+ Counterbalancing
+ Randomisation
+ Standardisation
What are the different variables other than extraneous that may need to be controlled in an investigation?
Where extraneous variables are important enough to cause a change in the DV, they become CONFOUNDING variables. There are many different types of extraneous varibales that psychologists need to take account of when designing their investogation :
+ Situational variables - variables connected with the research situation. For example, the temperature, time of day, lighting, materials etc. They are controlled through standardisation, ensuring that the only thing which differs between the two groups is the IV. (Making sure temperature is the same for both groups, the time of day is the same, etc.)
+ Participant variables - variables connected with the research participants. For example, age, intelligence, gender, etc. They are controlled through the experimental design, such as matched pairs, or by randomly allocating participants to conditions which helps to reduce bias.
What is random allocation?
Random allocation of participants to their groups, for example in an independent measures design, is an extremely important process in psychological research.
Random allocation greatly decreases the possibility that participant variables in the form of individual differences, such as mathematical ability, will adversely affect the results.
What is counter balancing?
Counterbalancing is used to combat the problem of order effects with repeated measures design.
— Researchers can counterbalance the order of the conditions.
The sample is split in half with one half completing the two conditions in one order and the other half completing the conditions in the reverse order.
— Any order effects should be balanced out by the opposing half of participants.
— For example, the first ten participants would complete condition A followed by condition B but the remaining ten participants would complete condition B and then A.
What is randomisation?
This is when trials are presented in a random order to avoid any bias that the order of the trials might present.
What is standardisation?
This is the process in which all situational varibales of a procedure used in research are kept identical, so that methods are sensitive to any change in performance. Under these circumstances changes in data can be attributed to the UV.
— In addition, it is far more likely that results will be replicated on subsequent occasions when research is standardised.
Why is paying attention to demand characteristics and investigator effects crucial in research ?
Both demand characteristics and investigator effects can act as confounding variables which affect the results of the research. Therefore, the researcher needs to exercise as much control over them as possible to maintain internal validity.
What are demand characteristics ?
Demand characteristics occur when the participants try to make sense of the research and change their behaviour accordingly to support what they believe are the aims of the investigation.
Demand characteristics are a problem as the participants act in a way to support the hypothesis rather than displaying natural behaviour, making the results lack validity.
— Conversely, the participant may deliberately try to disrupt the results, a phenomenon known as the ‘screw-you’ effect.
Demand characteristics are controlled by not allowing the participants to guess the aim of the research or the identity of the IV which can be achieved by using a single-blind experimental technique.
+ This is when only the researcher knows the true aim of the experiment, and a measure of deception has been used so that the participants cannot easily guess the aim.
+ Therefore, they are unable to try to either support or undermine the research on purpose.
+ EG. In medical trials when comparing the effects of a therapeutic drug with a placebo, where only the researcher knows which is which.
What are investigator effects?
Investigator effects are where a researcher (consciously or unconsciously) acts in a way to support their prediction.
— This can be a problem when observing events that can be interpreted in more than one way.
— For example, one researcher might interpret children fighting as an act of violence, while another might observe this as rough and tumble play.
Investigator effects are best controlled by not allowing either the participants or the researcher (investigator) to know the aim of the research and/ or identity of the IV.
+ This is achieved by using a double-blind experimental technique.
+ In this instance, only the person who originally designed the experiment knows the true aim, and a measure of deception has been used so that the participants and researcher are not away.
+ Therefore, either consciously or unconsciously, the investigator is unable to influence the participants.
