They definitely can touch the living!  I work at a residential facility for troubled/orphaned teens that has been in operation since 1895.  I have worked evening and over-night shifts for 6 years and have had numerous encounters with the spirits of former residents and staff!  On several occasions I have been touched by unseen hands that felt like those of little ones, been "kicked" in the leg a couple of times, and once I was "bitten" on the hand and have 2 small scars that look like those made by a child's teeth.  

I believe spirits do/can touch us. Maybe not all spirits, but I think some do. And  you have to be in tuned to them for yourself to notice in my opinion. The closest experience I had was I was at the sink and I felt someone behind me. It was so real, I can't explain it but when I turned around, no one was there. What else could of it been? No one else was in the house at the time.

This happened years ago and till this day I think of it every once in a while.