Standardized procedures: a set order of carrying out a study that is applied to all participants when necessary.

Random allocation: a procedure for putting participants into conditions by chance.

Counterbalancing: a procedure for evening out the order in which participants complete both conditions of an experiment.

Extraneous variable (EV): a variable that is not the IV but might affect the DV if not controlled.

Control: making sure procedures are the same when necessary. Not controlling procedures leads to the possibility of extraneous variables occurring and confounding the results. 

Ecological validity: the results of the investigation can be said to apply to real-life behavior. They are an accurate account of behavior in the real world.