An experiment is a psychological study used to explain cause and effect relationships. It is the technique of carefully varying conditions of an experiment so that the effects of changing one of the factors (independent variable) on another of the factors (dependent variable) can be observed. For example, a researcher may vary the amount of time a participant sleeps to observe the effect on memory performance. By utilizing control groups, random assignment, and standardized protocols, experiments contribute to limiting bias and enhancing accuracy. The reason this experimental procedure is important is because it provides psychologists with a way to move beyond mere observation and to test a specific hypothesis about behavior and psychology. However, areas of learning, emotion, decision making, and social influence have been studied with experiments. They are one of the most reliable methods for collecting evidence and they form the core of knowledge construction in the field of psychology.