Which perspective would researcher take if he were studying the instincts that humans survive?

Well for me I would say is their emotional radar

Explanation:

"In an uncertain world, those who survived always had their emotional radar—call it instinct, if you will—turned on. And Stone Age people, at the mercy of wild predators or impending natural disasters, came to trust their instincts above all else. That reliance on instinct undoubtedly saved human lives, allowing those who possessed keen instincts to reproduce. So for human beings, no less than for any other animal, emotions are the first screen to all information received."  - HBR