Legal Question in Legal Ethics in Illinois

Depends the kind of study, what if any compensation or benefits you derive, and how your under-age status affects the people who are conducting the study. If it has not gone too far and you can back out without consequence, that may be your best approach. But if you have paperwork on the participation requirements and the study you might want to have an attorney review the paperwork to see if there is anything "hidden" that could cause you problems.