Types of extraneous variables

Investigator effects (Investigator / experiment bias) (2)

A cue that makes participants unconsciously aware of the aims of the study

Helps participants work out what the researcher expects to find

Indirect investigator effects (2)

Distortions in the way people answer questions

They tend to answer questions in such a way that presents themselves in a better light

Demand characteristics

The tendency for participants to alter their behaviour merely as a result of knowing that they are being observed

Social desirability bias (2)

Any cues from the investigator that encourages certain behaviours in a participant, and might lead to a fulfillment of the investigators expectations

These can occur as a consequence of the investigator interacting with the participant

Participant variables

The features of the research situaton that may influence participants behaviour and so act as extraneous / confounding variables eg. order effects (improved performance on second task may be due to practise rather than IV)

Situatitonal variables (2)

Any characteristics of individual particpants that act as an extraneous variable when an independent groups design is used

These may include age, intelligence, motivation, gender (must be variables relevant to task in the study

Hawthorne effect

Behaviour influenced by knowing you are being observed

Hawthorne Effect: Investigator experimental design effect (2)

The investigator may operationalise the measurement of variables in such a way that the desired result is more likely

May limit the duration of the study for the same reason

Hawthorne Effect: Investigator loose procedure effect (2)

Where an investigator may not clearly specify the standarised instructions and/or procedures

Leaves room for results to be influenced by experimenter