Abstract Economic theory offers several explanations as to why shifting expectations about future economic activity affect current demand. Abstracting from whether changes in expectations originate from swings in beliefs or fundamentals, we test empirically whether optimism and pessimism about the economy trigger short-term fluctuations in private consumption and investment. Under the assumption that cyclical movements in private consumption and investment growth are exogenous to potential output growth forecasts far into the future, our results are consistent with the idea of private economic agents learning about future potential output growth and adjusting their current demand accordingly. We also propose a simple Keynesian model to illustrate that revisions in expected future income can affect short-term equilibria, in line with the results of the empirical analysis.