Originally Posted by FBinNY

It's easy to know which way to turn adjusters to change trim if you think about the housing rather than the inner wire. The adjuster doesn't directly change the inner wire which runs straight through. It effectively lengthens or shortens the housing, or total length of the cable's route.

So lengthening the housing has the same effect as shortening the inner wire, and vice versa. If you want the RD to trim inboard (for normal derailleurs sprung to move out) you turn the adjuster out lengthening the housing. To relax the cable and let the RD move toward the spring (outward) you'd shorten the housing.