Recall the case study method that was described in our first chapter and use you

Case studies of individuals with brain damage from disease, injury, or surgery can lead to hypotheses about brain-behavior relationships.
A drawback is that information gained from individual case studies may not generalize to other cases.
In such cases, the area of the brain damaged varies with each individual so no two cases are exactly alike.
Phineas Gage—Results are problematic because his pre-accident personality and behavior was not well documented and the exact extent of his lesion was unknown.
Split-brain patients have been carefully studied before and after surgery.  There are multiple cases, so comparisons can be made between people.  Because of their epilepsy, however, their brains may not have been functioning as that of a normal person before the surgery.