Further, for most children the positive effects of pre-kindergarten on skills largely dissipate by the spring of first grade, although the negative behavioral effects continue.The fact that the gains made by prekindergarten kids are dissipated by first grade doesn't surprise me. When I was a child, my mother read books to me and I also spent a lot of time watching Sesame Street. I learned to read before I reached first grade. The officials at my elementary school considered moving me up a grade, but since my math skills were too weak for the second grade, they didn't. Instead, my teacher sent me to the school library until all the other kids could catch up with me. The opportunity cost of trying to work with a kid that was advanced in one area was too high.
Might an advanced child feel frustrated that he is not being intellectually-stimulated enough, thus enhancing the negative behavior?