Research Issues

Extraneous variables

Any unwanted variable that might interfere with the DV or IV that isn’t controlled. Researchers attempt to identify these prior to the experiment to minimise them.

Confounding variables

A type of EV that varies systematically with the IV. Can’t tell if change in DV is due to IV or CV.

Demand characteristics

Any cue from researcher/situation that can be interpreted by the participant and reveal the aim of the study, thus possibly leading to a change in behaviour from the participant.

‘please-u effect’
‘screw-u effect'

Investigator effects

Any effect of the investigator’s behaviour on the research outcome (DV).

(e.g. study design, selection of participants, interaction with participants..)
Hugh Coolican (2006): expectancy effects, unconscious cues

E.g. leading questions

Randomisation

Minimise effects of EVs
Use of chance methods to reduce researcher bias when designing a study
e.g. memory study list of words randomly generated, or order of conditions randomised

Standardisation

participants subjected to same environment, information & experience
all procedures standardised (list of exactly what should be done in a study)
standardised instructions read to all participants
non-standardised changes = not EV