variables other than the IV that may effect the DV
situational variables
extraneous variables present in the environment
participant variables
extraneous variables linked to differences between participants
demand characteristics
when participants think they know the aim of the research and change their behaviour
order effects
when the behaviour of participants is influenced by the order in which they complete the different conditions of an experiment eg. becoming bored or gaining practice
investigator effects
when the researcher unintentionally gives clues to the participants about how they should behave
counter balancing
half the participants complete the conditions in one order
other half complete them in the other order
randomisation
randomly assigning condition A or B as a participants first or second test condition
single blind technique
when information of the study ( like the aim) is withheld from the participant
double blind technique
when the aims of the study are withheld from both the participants and researchers
standardisedprocedure
where the procedure of the study in the same across all conditions
