U.S. consumer confidence improved slightly in January to a three-month high, building on a gain the previous month, as Americans grew more optimistic about the medium-term prospects for the economy, a private research institute reported Tuesday.

The Conference Board said its consumer-confidence index rose to 98.1 this month from 96.3 in December. Consumer views of current economic conditions were relatively unchanged, amid a recent plunge in stock prices.

“For now, consumers do not foresee the volatility in financial markets as having a negative impact on the economy,” said Conference Board economist Lynn Franco.

But consumers grew more confident in the outlook in the coming six months, with respondents expecting slight improvement in business conditions, job prospects, and income growth amid a strong labor market, declining gasoline prices, and persistently low inflation.

Economists closely watch consumer-confidence reports for clues on consumer spending, which accounts for 70 percent of U.S. economic activity.