Ninety minutes later, the Fed published for the first time the predictions of the committee’s members on when they would raise interest rates. It showed that 11 of the 17 members expected the Fed to raise rates by the end of 2014. Taken together, the documents suggested that the Fed expected to keep rates near zero until late 2014, but probably not any longer than that.

Since the beginning of the financial crisis in 2007, the Fed has alternated bursts of activity with periods of rest, concluding several times that it had done enough only to find the economy still struggling to recover. The Fed announced last summer that the central bank intended to keep interest rates near zero through at least the middle of 2013, and that it would seek to reduce long-term interest rates through changes in the kinds of investment securities it holds. Since then, two meetings had passed without the introduction of any new programs.

The Fed’s latest action came after a run of better-than-expected economic data, suggesting to some analysts that the pace of growth might begin to rise without any further help. The Fed also is under relentless assault from Republican presidential candidates who have said that its policies are doing little good and will eventually spur inflation.

And there is growing criticism that the Fed’s policies are unfairly taking money from savers, including many seniors who planned their retirements around the interest rates that low-risk assets like bank deposits used to pay.

Mr. Bernanke said Wednesday that the Fed was aware of this, but it was acting again because it still did not believe that it has done enough. At the same time, he suggested that the Fed was not on the verge of more drastic measures, like further expanding its portfolio of mortgage-backed securities.

Such purchases remain under consideration, Mr. Bernanke said, but only “if we see that the recovery is faltering or if we see that inflation is not moving towards target.”

As part of its transparency campaign, the Fed also published Wednesday a statement of its long-term goals, formalizing its longstanding commitment to maintain inflation at about 2 percent a year. The Fed also said that it was equally committed to minimizing unemployment, but that its exact goal would vary based on economic circumstances. It said the goal now was to reduce unemployment below 6 percent.