Organizations increasingly use corporate online ideation platforms to foster individual innovativeness. Recent research, however, has shown the downside of such contests—the selection of ideas is not entirely rational. Analyzing the impact of content scarcity, which occurs when ideators provide very little issue‐relevant information when submitting ideas, contributes to this new literature stream. The main argument is that evaluators increasingly rely on heuristics based on issue‐irrelevant information when content scarcity obstructs reflective decision‐making. The default‐interventionist model of decision‐making in combination with the Yale attitude change approach allows us to examine the mechanisms evaluators apply when content scarcity occurs. The hypotheses are tested on an extensive data set of 3025 ideas. The results show that content scarcity affects the evaluators' decision‐making process by preventing them from intervening their first intuitive decision. The scarcer the content of the submitted idea, the stronger the persuasiveness of issue‐irrelevant aspects that affect idea selection: aspects of the ideator, message, and community.