Minutes from the June meeting of the Federal Open Market Committee, the Fed’s main policy-making arm, indicated that a few officials had a new worry: deflation. Those officials believe that inflation  which is running at about half the Fed’s desired range of 1.7 to 2 percent  has been so low that it could turn into a dangerous spiral of falling prices like the one that has plagued Japan since the mid-1990s.

“Forecasts are very uncertain, but I don’t view deflation as a near-term risk for the United States,” Mr. Bernanke told Mr. Shelby, noting that inflation expectations had remained stable.

“I think the Federal Reserve does have the capacity, the tools, should deflation occur  which, again, I don’t believe is very likely  to reverse it, and we would be very assiduous in doing that,” the chairman added. “I don’t consider that to be a very high risk at this point.”

Mr. Bernanke’s testimony took a more cautious tone than he did in February.

The chairman noted weakness in the housing market, “with the overhang of vacant or foreclosed houses weighing on home prices and construction.”

He called the slow recovery of the job market “an important drag on household spending.” And he noted that the growth in private payrolls  about 100,000 jobs a month in the first half of the year  was “insufficient to reduce the unemployment rate materially.”

The Fed expects the economy to grow this year by 3 to 3.5 percent, picking up only slightly, to 3.5 to 4.5 percent, in 2011 and 2012. The unemployment rate is projected to drop to 7 to 7.5 percent by the end of 2012  still far higher than the 5 to 5.3 percent that the Fed now considers to be full employment.

Mr. Bernanke said of the committee’s last meeting: “Most participants viewed uncertainty about the outlook for growth and unemployment as greater than normal, and the majority saw the risks to growth as weighted to the downside.”