FYI, I didn't have a dummy BUT I sucked my thumb until I was 8y/o. My Mum encouraged me to stop, but didn't want to pressure me. I put a lot of pressure on myself though, because at 8 y/O I was too afraid to go on sleepovers in case my friends discovered that I was a thumb-sucker. I don't know how, but at some point I just stopped sucking and settled myself to sleep without it. At least the dummies can be removed...thumbs can't!