experiment in something
to conduct research or experiments about something. The research group is experimenting in the field of biomechanics. We want to experiment in thermodynamics.
experiment (up)on someone or something
to use someone or something as the subject of an experiment. (Upon is formal and less commonly used than on.) Do you think we should experiment upon people? The researchers were experimenting on a new drug that might cure rabies.
experiment with someone or something
to try different experiments on someone or something; to use different people or things as key variables in an experiment. They are supposed to be experimenting with new drugs. We no longer experiment with animals.