The big mistake among some dualists they say that the brain is a radio or tv receiver but when they say that they don't point out. That the analogy their using is not a simple one. That the brain is not a simple television or radio in it's workings. But that the brain is an advance tv or radio. The brain being a advance tv or radio is in accord with the facts, such as that the brain is very complexed, also that mediums a lot of the time have trouble tuning into spiritual realities. This would explain it because the more advanced the brain is which we humans have a very advance brain the more information gets filtered out. That information could be crucial in it's possible connection with these spiritual realities that mediums attempt to communicate with.
Of course physicalists say that the brain is an advanced computer and that the mind is software, the brain is the hardware. The problems with this analogy
1. The Chinese Room Argument [John Searle]
2. The failure Of Artifical Intelligence
3. Certain things in the brain that conflict with the whole " brain is a advanced computer