The phrase "pioneering researchers" refers to people who are the first to explore and discover new things in their field of study. They are like trailblazers who lead the way for others to learn and benefit from their discoveries. Full definition
They are pioneering researchers in family engagement and community organizing for school reform. (gse.harvard.edu)
We have known, since Frederick Bartlett's work in the 1930s, and subsequently from the work of pioneering researchers such as Elizabeth Loftus, that memory is reconstructive, rather than reproductive. (seedmagazine.com)
As Hans Selye, pioneer researcher on stress, makes clear, it is our attitudes toward events in our lives that turn them into «distress» or «eustress» (good stress), not the events per se. (religion-online.org)