Eye movements reveal rapid concurrent access to factual and counterfactual interpretations of the world.

Imagining a counterfactual world using conditionals (e.g., If Joanne had remembered her umbrella . . .) is common in everyday language. However, such utterances are likely to involve fairly complex reasoning processes to represent both the explicit hypothetical conjecture and its implied factual meaning. Online research into these mechanisms has so far been limited. The present paper describes two eye movement studies that investigated the time-course with which comprehenders can set up and access factual inferences based on a realistic counterfactual context. Adult participants were eye-tracked while they read short narratives, in which a context sentence set up a counterfactual world (If . . . then . . .), and a subsequent critical sentence described an event that was either consistent or inconsistent with the implied factual world. A factual consistent condition (Because . . . then . . .) was included as a baseline of normal contextual integration. Results showed that within a counterfactual scenario, readers quickly inferred the implied factual meaning of the discourse. However, initial processing of the critical word led to clear, but distinct, anomaly detection responses for both contextually inconsistent and consistent conditions. These results provide evidence that readers can rapidly make a factual inference from a preceding counterfactual context, despite maintaining access to both counterfactual and factual interpretations of events.