Why do two completely different pictures look the same to the patient

Here are two images of a house.There’s one obvious difference,
but to this patient, P.S.,they looked completely identical.P.S. had suffered a stroke that damaged the right side of her brain,leaving her unaware of everything on her left side.But though she could discern no difference between the houses,when researchers asked her which she would prefer to live in,she chose the house that wasn’t burning—not once, but again and again.P.S.’s brain was still processing information from her whole field of vision.She could see both images and tell the difference between them,she just didn’t know it.