Using the phenomenology of retrieval failures to understand curiosity for inaccessible and unavailable knowledge.

Curiosity arises from metacognitive evaluations of existing knowledge and drives information-seeking behaviors. Past research examining curiosity when retrieval fails used measures of confidence, Feeling-of-Knowing, and Tip-of-the-Tongue states (Brooks et al., 2021; Dubey & Griffiths, 2020; Metcalfe et al., 2017). The present study examines curiosity for irretrievable information by employing phenomenological states of memory failures (Umanath et al., 2025). Participants answered general knowledge questions and selected a phenomenological category to represent any retrieval failure experience, choosing among four categories from "It's on the tip of my tongue" (closest to potential retrieval) to "I have never known or seen this information" (furthest from retrieval). They then rated their curiosity to see the answer for each question. Consistent with the Proximity to Retrieval Success framework (Umanath et al., 2025), curiosity was higher for categories closer to retrieval and decreased as perceived proximity to retrieval decreased.