Zero-shot search termination reveals a dissociation between implicit and explicit metacognitive knowledge

In order to infer that a target item is missing from a display, subjects must know that they would have detected it if it was present. This form of counterfactual reasoning critically relies on metacognitive knowledge about spatial attention and visual search behaviour. Previous work on visual search established that this knowledge is constructed and expanded based on task experience. Here we show that some metacognitive knowledge is also available to participants in the first few trials of the task, and that this knowledge can be used to guide decisions about search termination even if it is not available for explicit report.