An experiment in which the true purpose is hidden from the researcher as well as from the participant is called

a. controlled experiment. double-blind experiment. correlational study. blind experiment.

This is the definition of a double-blind experiment. In it, both researcher and participant do not know what the scope of the study is or what the study is trying to understand. This allows for unfiltered data to be gleaned by both the researcher and the participant, free from bias or unintentional behaviors.