The biological level of analysis in psychology refers to the study of how human behaviour, thoughts and emotions can be affected and affect the biological factors/ physiology of human body. Laboratory experiments, case studies and correlation studies are the three main research methods applied in supporting the principles of the biological of analysis in psychology.
First, laboratory experiments. Laboratory experiments are research methods that help to establish cause-effect relationship between two variables. They are applied for developing the casual relationship of manipulated variables which help to increase psychological knowledge such as evolution, development, maintenance, alteration, control or biological significance of behaviour mostly through clear scientific purposes and might or might not benefit health and welfare of human or animals. Laboratory experiments are applied through the process of creating clear operational definition and mostly quantifiable independent variable, dependent variable and controlled variables. Researchers often manipulate the independent variable for figuring out the change in the dependent variable when there is a change in the independent variable while the controlled variables such as laboratory environments remain constant. Researchers often maintain a population of animals such as rats, fruit flies and pigeons as laboratory experiments often involve animal experiments since limited number of human-beings are willing to present their informed consent due to the possibility of harm and injury caused by the experiment. One of the classic research examples which was held through the research method of laboratory experiment was known as Daneau 1969 monkey trials. This aim of the research as to test whether non-human primates would voluntarily initiate self-administration to drugs through provided monkeys free