The method chosen depends on many factors including cost, facilities, the researchers goals and preferences, the behavior to be studied and the purpose or goals of the study. Some of the experimental methods are easier for the researcher to control and therefore produce more conclusive results than others. However, all experiments begin with an experimental hypothesis, typically derived from existing theory, - in other words what the experimenter expects to happen. This article will briefly describe what the methods are and the pros and cons for each. The experimenter directly manipulates the presence or strength of a factor or variable and measures how behavior is affected by it.
Stress has a detrimental effect on performance.
Also, it can be difficult to generalize results obtained in the lab to behavior in the real world. This involves simply observing and describing behavior in specific settings. Instead, naturally occurring variations in both the independent and dependent variable are simply measured to see how they relate to each other. Most often used by clinical and personality psychologists. A detailed analysis of conversations.