controlled variable
Testing a hypothesis under controlled condition is a scientific experiment.
Controlled (or control) variables are things that are kept the same during an experiment. There are usually many- for example, when testing how light intensity affects photosynthesis, the controlled variable would be the type of plant used, or the color of the light.
Homeostatic mechanisms return the body to its normal state. Most of these are controlled by negative feedback.
Controlled experiments contain two parts, the control group and the variable group. The variable group is the group that receives treatment and attention. These two groups are used to compare to each other at the end of the experiment.