What Do You Call Someone Conducting an Experiment? Terms Explained

What Do You Call Someone Conducting an Experiment?

The short answer is experimenter, but that's rarely the full picture. In real research settings, the person running an experiment goes by many titles depending on their role, credentials, and the type of study.

This isn't semantic nitpicking. Getting the terminology right matters when you're writing a lab report, reading a research paper, or trying to figure out who's responsible for what in a study.

The Main Terms You'll Encounter

Experimenter

The most straightforward term. An experimenter is anyone actively running an experiment—measuring variables, controlling conditions, collecting data. It's broad and works in casual contexts.

Most textbooks and introductory science courses use this term because it doesn't require any specific credentials.

Researcher

A step broader. A researcher designs and conducts studies, which may or may not involve experiments. Researchers do literature reviews, develop hypotheses, analyze data, and publish findings. Experiments are just one tool in their arsenal.

You'll see this word constantly in academic papers: "the researchers found that..."

Investigator

This term shows up heavily in clinical and medical research. An investigator is someone who examines a phenomenon under controlled conditions. The word carries a slightly more formal weight than "experimenter."

In drug trials and medical studies, investigators often have MDs or PhDs and are responsible for participant safety and data integrity.

Principal Investigator (PI)

This is the big one in formal research settings. The principal investigator is the person who takes overall responsibility for a research project. They secure funding, design the study, supervise the team, and are ultimately accountable for results.

Graduate students and lab technicians might run individual experiments, but the PI's name goes on the grant application and the final paper.

Scientist

Anyone conducting systematic experiments to build knowledge can be called a scientist. It's an umbrella term that covers physicists, chemists, biologists, psychologists, and anyone else following the scientific method.

Not every experimenter is a scientist (think home brewers running informal tests), but most scientists conduct experiments as part of their work.

Context Matters More Than the Title

The same person might be called an experimenter in one context and a principal investigator in another. A psychology PhD student running participants in a memory study is an experimenter when actually running the sessions, but becomes a researcher when writing up the findings, and might be listed as co-investigator on a grant.

Here's how these terms break down across common scenarios:

Other Titles Worth Knowing

• Lab technician — runs experiments under supervision, often handles the day-to-day machinery and procedures
• Research assistant — supports experiments, collects data, usually works under a PI
• Study director — common in pharmaceutical and toxicology studies; responsible for the technical conduct of the study
• Co-investigator — assists the PI, brings specialized expertise to the project

How to Identify Roles in a Research Paper

Most peer-reviewed papers include an author list with affiliations. The first author typically ran the experiments. The last author is usually the PI. Corresponding authors handle communication with journals and readers.

Check the methods section. That's where authors describe exactly who did what: "Data were collected by J. Smith and analyzed by K. Lee under the supervision of Dr. Chen."

The Bitter Truth

Nobody outside academia cares about these distinctions as much as academics do. In everyday conversation, "the person doing the experiment" works fine. The titles matter most when legal or administrative responsibility enters the picture—which is why IRBs, funding agencies, and journals care about them, and why you should too when you're writing for those audiences.

For homework assignments, "experimenter" or "researcher" is perfectly adequate. For publications, grants, or anything with regulatory teeth, use the precise term that matches the role and credentials of the person involved.