WASHINGTON  The Federal Reserve chairman, Ben S. Bernanke, said Tuesday that it was “very likely” that the recession had ended although he cautioned that it could be months before unemployment rates dropped significantly.

“Even though from a technical perspective the recession is very likely over at this point, it’s still going to feel like a very weak economy for some time as many people will still find that their job security and their employment status is not what they wish it was,” Mr. Bernanke said in response to a question about unemployment trends. “That’s a challenge for us and all policy makers going forward.”

The cautiously optimistic assessment came at the end of a speech at the Brookings Institution observing a year after a market crisis that was precipitated by the collapse of the investment bank Lehman Brothers.

Image U.S. Chairman of the Federal Reserve Ben Bernanke listens to questions after making remarks about a year of economic turmoil at the Brookings Institution in Washington Tuesday. Credit... Jim Young/Reuters

Shortly before the speech, the Commerce Department reported that retail sales had surged in August as consumers swapped old cars for new ones under the “cash-for-clunkers” program. The increase, by a seasonally adjusted 2.7 percent rate over the previous month, widely surpassed analysts’ expectations and was the largest monthly increase since January 2006.