Suggest one effect if a double-blind trial had not been used in this study.
Marks: Award 2 marks for an appropriate suggestion stated and applied to study with detail / elaboration / example.
Award 1 mark for an appropriate suggestion identified but not applied.
Answers may include (other appropriate responses to be credited).
Note: 'effect' could be on anything, not just validity.
Note: only one of the two possibilities below is required for 2 marks.
- participant bias: if a participant knows which group they are in, nalmefene (or naltrexone) group or the control (placebo) group, they might change their behaviour to support the aims of the study (or go against it) (2 marks).
- experimenter bias: if an experimenter knows which group a participant is in nalmefene (or naltrexone) group or the control (placebo) group, they may bias their behaviour toward the participant to support the aims of the study (2 marks).