I'll believe it unless it's too absurd: Spontaneous visual perspective-taking as prior-based heuristic inference

The underlying mechanism of visual perspective-taking (VPT)-the ability to represent what others see-remains contested. Perceptual simulation theory proposes that VPT involves reconstructing others' visual experiences, whereas heuristic accounts argue that it relies on symbolic inference grounded in naïve optics. Evidence for heuristics largely comes from explicit report tasks, leaving open whether spontaneous (implicit) VPT in an agent-irrelevant task is driven by the same mechanism. A further possibility is that apparent "simulation failures" arise because observers lack prior visual information about what the other sees from their viewpoint. Across two experiments, participants performed an agent-irrelevant line-length judgment task while receiving plausible, absent, or implausible prior visual information from the agent's viewpoint. Experiment 1 showed a robust perspective-consistent bias under plausible priors, no bias without priors, and a weaker bias under implausible priors. A control experiment ruled out priming. Experiment 2 parametrically varied implausibility in a Ponzo-style layout and revealed a boundary condition: priors ranging from plausible to moderately implausible continued to bias judgments, whereas highly implausible priors were discounted. These results support a bounded, resource-rational heuristic account in which others' visual information acts as plausibility-weighted cues integrated with one's own visual input, rather than being reconstructed via perceptual simulation.