When carrying out a piece of research, a psychologists main concern is looking at the effects of just the IV on the DV, in order to do this, all other extraneous variables (EVs) need to be controlled.
Experimental Methods in Psychology.
There are three experimental methods in the field of psychology; Laboratory, Field and Natural Experiments. Each of the experimental methods holds different characteristics in relation to; the manipulation of the IV, the control of the EVs and the ability to accurately replicate the study in exactly the same way.
