Right and left hemisphere cooperation for drawing predictive and coherence inferences during normal story comprehension

Abstract

In three experiments, healthy young participants listened to stories promoting inferences and named inference-related test words presented to the right visual field-Left Hemisphere (rvf-LH) or to the left visual field-Right Hemisphere (lvf-RH). Participants showed priming for predictive inferences only for target words presented to the lvf-RH; in contrast, they showed priming for coherence inferences only for target words presented to the rvf-LH. These results, plus the fact that patients with RH brain damage have difficulty drawing coherence inferences and do not show inference-related priming, suggest that information capable of supporting predictive inferences is more likely to be initially activated in the RH than the LH, but following coherence breaks these concepts (now coherence inferences) are completed in the LH. These results are consistent with the theory that the RH engages in relatively coarse semantic coding, which aids full comprehension of discourse.

FIG. 1

Participants’ mean priming (Unrelated-Inference-related latencies) for test words presented to the lvf-RH and rvf-LH at five test points: Test point (1) from Experiment 1; (2) and (3) from Experiment 3; (4) from combined data of Experiments 1 and 2; and (5) from Experiment 2. Test points (1) and (2) assessed inference-related activation at points when inferences would be considered predictive, test point (3) assessed activation during the transition from predictive to coherence inferences, and Coherence point (4) and Resolution point (5) assessed inference-related activation at points when inferences were necessary for coherence: “The shuttle sat on the ground in the distance (1), waiting for the signal to be given (2). After a huge roar (3) and a bright flash, the shuttle disappeared into space (4), leaving clouds of smoke in its wake (5), and the audience cheered.”