Hemispheric processing of inferences during text comprehension: the role of consistency and task difficulty

Although the hemispheres likely carry out different processes during reading, currently little is known about how the consistency effect and the difficulty of the task influences hemispheric processing during text comprehension. In the current study participants read texts promoting an inference, and performed a lexical decision task to inference-related targets presented to the left visual field-right hemisphere or the right visual field-left hemisphere. To manipulate the consistency of information targets were either consistent or inconsistent with the inference. To manipulate difficulty the antecedent and its referent were either separated by two sentences (i.e., the less-difficult condition) or four sentences (i.e., the more-difficult condition). In the consistent condition facilitation was greater in the left hemisphere than the right hemisphere. In the inconsistent condition facilitation was greater in the right hemisphere than the left hemisphere. When analyses were combined across conditions, consistent targets showed greater facilitation in the left hemisphere than in the right hemisphere. Interestingly the level of difficulty did not mediate how the hemispheres process inferences. The current findings suggest that the consistency of information, rather than the difficulty of a task, primarily influences inference generation in the cerebral hemispheres.