Definition: Other factors that could influence results.
Order Effects: P’s may perform differently on 2 conditions because of the order in which they are performed. (practice, bored, tired)
This is controlled by counterbalancing (ABBA)
Participant Variables: P’s characteristics (ag, gender, personality) These only occur in independent groups design.
The Hawthorne effect - P’s aware they’re being observed = perform better.
The Screw You Effect…