A true experiment is defined as an experiment conducted where an effort is made to impose control over all other variables except the one under study. Independent variable – this is the variable that the experimenter manipulates in a study.

One way to minimize possible bias is to record or score behavioral data blind to treatment, group, or individual. Another way to reduce bias is for researchers to analyze subsets or entire sets of data independently of one another and to obtain high inter‐observer reliability of behavioral coding.

Experimenter effect (not ‘effects’) is the tendency on the part of the experimenter/researcher to influence the participants or to interpret the data/findings to arrive at the result they are seeking to obtain. This is typically done subconsciously, though it may be done consciously as well.

Quasi-experiments are most likely to be conducted in field settings in which random assignment is difficult or impossible. They are often conducted to evaluate the effectiveness of a treatment—perhaps a type of psychotherapy or an educational intervention.

Four major design types with relevance to user research are experimental, quasi-experimental, correlational and single subject. These research designs proceed from a level of high validity and generalizability to ones with lower validity and generalizability. First, a note on validity.

The greatest disadvantage of quasi-experimental studies is that randomization is not used, limiting the study’s ability to conclude a causal association between an intervention and an outcome.

How to Conduct a Psychology Experiment

1. Ask a question or find a research problem to solve.
2. Determine what you will test to answer this question.
3. Review current knowledge on the subject.
4. Design an experiment.
5. Perform the experiment.
6. Analyze results using statistical methods.
7. Draw your conclusion and share the results with the scientific community.

Designing psychology experiments that return useful, consistent and reliable results is critical to researcher’s ability to establish cause-and-effect relationships in the many variables that influence behavior. All psychology experiments seek to describe, explain and predict behaviors or mental processes.

This is a list of the 25 most influential psychological experiments still being taught to psychology students of today.

1. A Class Divided.
2. Asch Conformity Study.
3. Bobo Doll Experiment.
4. Car Crash Experiment.
5. Cognitive Dissonance Experiment.
6. Fantz’s Looking Chamber.
7. Hawthorne Effect.
8. Kitty Genovese Case.

Social psychologists utilize experimental techniques to study how people are influenced by groups. Health psychologists rely on experimentation and research to better understand the factors that contribute to wellness and disease.

Experimental psychologists use scientific methods to collect data and perform research. They can work in varied settings, including universities, research centers, the government and private businesses.