Controlling variables Flashcards
Extraneous variables can be split into four main groups
-situational variables
-demand characteristics
-investigator effects
-participant variables
situational variables
certain aspects of the situation or environment may affect the participants behaviour in an experiment e.g noise, lighting
how to control for situational variables
researchers should ensure that each group of participants complete the experiment under the same situational conditions
demand characteristics
features or cues in an experiment which help participants work out the aim of the study
how to control demand characteristics
an independent measures design or matched pairs design could be used
investigator effects
occur when the researcher unconsciously influences the results, maybe by treating some participants different to others
how to control for investigator effects
written standardised instructions can be used so the researcher can’t influence the participants when giving instructions
participant variables
when individual characteristics of participants affect their behaviour in an experiment
how to control participant variables
a repeated measures design or matched pairs design could be used
4 main techniques used to control extraneous variables
standardisation
random allocation
counterbalancing
randomisation
standardisation
making things the same or standard across conditions
random allocation
allocating participants to conditions by chance- each participant has an equal chance of ending up in each condition
counterbalancing
used in a repeated measures design.
one group would do condition A then B, the other group would do B then A
randomisation
controlling variables by means of chance. can also be used to decide the order of conditions in a repeated measures design
