Reasoning and Brain Damage: prediction and explanation in left and right hemisphere patients

The left and right hemispheres of the brain are generally known to be associated with different types of processing. The left hemisphere is associated with linguistic, sequential and logical processing. The right hemisphere is associated with abstract and visuospatial reasoning and creative processing. In narrative discourse, explanation can be considered abductive reasoning, described as a creative type of reasoning which generates new ideas, and prediction can be considered logical deductive reasoning. Given these known associations with hemisphere processing and reasoning associations, it would be expected that patients with left hemisphere brain damage would exhibit more evidence of explanation versus prediction in reasoning and patients with right hemisphere brain damage would exhibit more evidence of prediction versus explanation in reasoning. Contrary to expected evidence, left hemisphere patients produced more utterances of prediction than of explanation and right hemisphere patients produced more utterances of explanation than prediction on a narrative discourse task. Linguistic processing capabilities and cognitive processing capabilities are jointly discussed as explanations for these results.