Small scale version of an investigation that occurs before real investigation to check that procedures work and then the researcher makes changes if necessary
What is a single-blind procedure
Ppts won't be told true aim of the experiment i.e. other details may be hidden - controls demand characteristics
What is a double-blind procedure?
Neither the ppt or researcher is aware of the aims of the experiment (e.g. drug trials - treatment may be given by someone independent of investigation)
