Scholars increasingly conceptualize populism by whether politicians use people-centric and anti-elite appeals that pit a homogeneous people against a corrupt elite. These appeals reflect “thin” ideology because they offer no programmatic content and thus politicians must pair these appeals with more substantive positions, termed their “host” (or thick) ideology, which often consists of nativism on the right (e.g., espousing anti-immigrant positions) and socialism on the left (e.g., prioritizing redistribution). An emerging literature has thus sought to estimate whether populists garner support due to their thin ideology or their substantive host ideology. To date, no research has validated whether populism treatments (1) truly operationalize populist thin ideology, and (2) do so without manipulating host ideology. Results from three conjoint validation experiments fielded in both the United States and the United Kingdom show that thin ideology treatments successfully manipulate the underlying concepts but caution that some operationalizations also affect perceptions of host ideology.
