One research method used to study human behavior from the biological approach is experiment. The biological level of analysis (BLOA) states that all cognitions, emotions and behaviours have a physiological basis. In terms of a biological basis, symptoms and disorders arise from physiological processes, such as hormones, neurotransmitters and the brain, which cannot be directly observed. These theories are tested using research methods such as experiments.

Experiments are used to determine the cause and effect relationship between two variables (independent (IV) and dependent (DV) variables). Researchers manipulate the IV and measure the DV. Experiments are based on hypothesis testing - that is, making a measurable and testable hypothesis and then seeing if the results of the study are statistically significant so that they can reject the null hypothesis. In addition, an experiment must contain at least one group that receives a treatment (the manipulation of an independent variable), and a control group does not receive the treatment.

In a true experiment, participants are randomly allocated to conditions. In understanding the biological basis of cognitive processes, laboratory experiments are mainly used because it allows the researchers to pose strict control over as many extraneous variables as possible.

One study that uses experiment  is the Setiawan study. The aim of the Setiawan et al (2013) was to investigate whether one's level of sensitivity to alcohol and personality traits are related to dopamine responses in the brains of young, healthy social drinkers.

The procedure is as follows. Researchers studied 26 healthy young social drinkers from the city of Montreal and the university community at McGill. The sample ranged from 18 - 30 years old.  The sample consisted of 8 women and 18 men. To participate, they had to be free of any diagnosis of mental illness or drug dependence other than nicotine or caffeine. None of the participants was identified as having AUD, but 11 of the participants reported having a family member with AUD.

Participants were asked to first fill in a series of questionnaires - including a lifetime drug and alcohol use questionnaire and the Tridimensionality Personality Questionnaire.  The researcher categorised the drinkers as either high or low risk for alcoholism based on personality traits and having a lower intoxication response to alcohol - that is, they did not feel as drunk despite having drunk the same amount as other drinkers.

Each participant underwent two PET scans on separate days.  The conditions were counterbalanced. Before the scan, a urine drug test and a Breathalyzer test were used to confirm that the participants were drug-free. They were also asked to abstain from nicotine and caffeine on the day of each scan.

Participants were told that they may or may not receive alcohol on either day. 30 minutes before the scan, they were asked to drink a mixture of orange juice and lemon-lime soda - or the same volume of the same drink, but including alcohol. Blood samples were taken before the drink, and then at 30, 60, and 90 minutes thereafter to measure blood alcohol levels.

The results showed that when drinking alcohol, those who were considered "high risk" for alcoholism showed significantly greater activity in the mesolimbic reward pathway - that is, greater dopamine levels in response to alcohol consumption. It should be noted that there was no significant difference in the two groups' lifetime exposure to alcohol, suggesting that the result is not simply because of one's history of alcohol consumption.  Members of the low-risk group, on the other hand, showed a decreased dopamine response.

The biological level of analysis (BLOA) supports the understanding of cognition, emotions, and behavior based on physiological processes, such as neurotransmitter responses and brain activity. The focus on the mesolimbic dopamine pathway—an area linked to the brain's reward system—ties directly into the BLOA premise that behaviors are a result of physiological factors, like dopamine release. This study was a true experiment, where participants were randomly assigned to conditions to control extraneous variables, ensuring the cause-and-effect relationship between alcohol consumption (IV) and dopamine response (DV) could be investigated. Participants underwent two PET scans, with alcohol consumption manipulated to test its direct effect on brain activity. Random allocation to conditions allowed for the differentiation between participants' inherent risk for alcoholism and their physiological response to alcohol. The results clearly demonstrated a cause-and-effect relationship between alcohol consumption and increased dopamine activity in the brain's reward pathways, particularly for those considered "high risk" for alcoholism. The controlled nature of the experiment (such as pre-scan tests and controlled alcohol exposure) enabled researchers to pinpoint dopamine response as a physiological reaction to alcohol consumption, rather than a result of previous alcohol exposure.

The results clearly demonstrated a cause-and-effect relationship between alcohol consumption and increased dopamine activity in the brain's reward pathways, particularly for those considered "high risk" for alcoholism. The controlled nature of the experiment (such as pre-scan tests and controlled alcohol exposure) enabled researchers to pinpoint dopamine response as a physiological reaction to alcohol consumption, rather than a result of previous alcohol exposure.

Setiawan et al. effectively employed a laboratory experimental method to investigate the impact of alcohol on brain function and its subsequent influence on participant behavior. By using a controlled experimental setup, they were able to isolate the effects of alcohol, establishing a clear causal link between alcohol consumption and changes in both brain activity and behavior.