The Medium

Across the game you'll be prompted to press the X button (default) to investigate items in the environment. Every time you do, it will count towards this achievement.

I unlocked this very early, before I even finished the first objective, which is to prepare your foster father for his funeral. If you're through at examining everything in the apartment and on the way to the funeral home, you'll get this as your first or second achievement.

Also, be sure to feed the cat before you leave the apartment for a missable achievement!