Are Survey Experiments Externally Valid?

Researchers use survey experiments to establish causal effects in descriptively representative samples, but concerns remain regarding the strength of the stimuli and the lack of realism in experimental settings. We explore these issues by comparing three national survey experiments on Medicare and immigration with contemporaneous natural experiments on the same topics. The survey experiments reveal that providing information increases political knowledge and alters attitudes. In contrast, two real-world government announcements had no discernable effects, except among people who were exposed to the same facts publicized in the mass media. Even among this exposed subsample, treatment effects were smaller and sometimes pointed in the opposite direction. Methodologically, our results suggest the need for caution when extrapolating from survey experiments. Substantively, we find that many citizens are able to recall factual information appearing in the news but may not adjust their beliefs and opinions in response to this information.