Your Mandarin is a long-time student of psychology and has something like fifteen or sixteen degrees in it; its tough to remember exactly. One of the more weird things youll encounter is the McGurk Effect. Watch this video:
That is not your Mandarin speaking in the video, otherwise you would all be obeying. But the point is that not all illusions are optical; some are auditory, although in this case it is more an illusion caused by fooling sensory integration in your brain.
For example, one of the more prevalent examples of the McGurk Effect is that when someone points out the President screwed up for the umpteenth time, the media simply hears it was the Republicanss fault. Same thing, exactly. Your brain knows better but it still cant figure it out.