I did not say Option ARMs will cause payment shock *before* the reset period. They cause payment shock once the loan resets. Same with ARMs and I/Os. While you are in the intro teaser-rate period, the payment stays the same (or changes a little bit as Jim explained).
Even if the Fed lowers interest rates back to 2002 levels, the resets are going to cause a payment shock for tens of thousands of San Diegans who made minimum payments on their Option ARMs. What effect will that have on the housing market?