What confidence?

After Donald J. Trump won the presidential election, Americans’ optimism about the economic future soared. But midway through the year, that optimism has not translated into concrete economic gains.

This seeming contradiction exposes a reality about the role of psychology in economics — or more specifically, how psychology is connected only loosely to actual growth. It will take more than feelings to fix the sluggishness that has been evident in the United States and other major economies for years. Confidence isn’t some magic elixir for the economy: Businesses will hire and invest only when they see concrete evidence of demand for their products, and consumers intensify their spending only when their incomes justify it.

The sharp rise in economic optimism after the election came through no matter how the question was asked or who answered, whether the survey was intended to capture consumer confidence or consumer comfort or consumer sentiment. It was true in surveys of small-business owners and of C.E.O.s of some of the biggest companies in the world. And the rise during the winter months in these surveys has mostly been sustained in the months since.

But the economy is plodding along at the same modest rate it has for the last eight years nonetheless — at least when you look at “hard” data around economic activity instead of “soft” data like surveys, as analysts put it.

President Trump said on Twitter on Sunday that the stock market was at an “all-time high” and that unemployment was at its lowest level in years, both of which are true (he added that wages would start going up, which is certainly possible).

But in overall measures of economic activity, the expansion looks much as it has for years, with steady growth of around 2 percent. The Trump economy so far looks an awful lot like the Obama economy.

For all of business executives’ apparent enthusiasm, the nation is adding jobs more slowly in 2017 than it did in 2016, and investment spending by businesses is growing modestly; new orders for capital goods are up only 0.7 percent so far in 2017.

Consumers’ spending was 2.7 percent higher in the first four months this year than in the same period of 2016, adjusted for inflation — which is slower than the 3.2 percent year-over-year gain at the end of 2016.

And while the stock market has been surging and the Federal Reserve has raised short-term interest rates, long-term Treasury bond yields remain very low, suggesting that traders do not buy the idea that growth is poised to accelerate. A falling dollar suggests currency markets see improving prospects in Europe and elsewhere.

There is no sign a recession is brewing, but neither is there evidence for the kind of boom you might expect if you believe that confidence is a crucial driver of economic growth.