An interesting thought

I recently completed an assignment on the EMH and behavioral finance. Looking mainly at critiques of both. I just had an interesting thought as I sit here witnessing g8 plummet. In one of the essays I read by Robert Shiller he points out a concept called overreaction and under reaction. I think I just understood what it meant. G8 has just released an update regarding it acquisition. The stock has fallen since its release and this could be exhibiting overreaction by the market or vice versa. I think that's what Shiller was getting at. I.e the price shouldn't have fallen that far or maybe it should fall further? I think it's important to stick to your senses and think independently of the market. As I get deeper into this game I'm worrying alot less about what prices are doing and focusing on businesses. I use to check my stockbroking account at least 30 times a day when I first started and now I forget to check it. While I knew not to do this before I started investing my own ,money it was really hard not to watch the tapper. However, I'd never let a change in the  price force me into making a decision in isolation of fundamentals. If however, no business fundamentals have changed and price of a stock I own or would like to own falls by a certain amount this will potentially trigger a buy.