"As I later learned, my brain was contending with the “ventriloquist effect,” first noted in a study in the 1890s but named by a research team in the 1960s. The basic insight, that “visual information biases the spatial localization of auditory events,” is a key finding in behavioral and neurological research. When it comes to spatial processing, human vision is, by dint of evolutionary adaptation, generally stronger than the auditory sense. (Which is perhaps why it’s infuriatingly difficult to locate a cellphone that is ringing two feet away from you if it’s concealed under a couch pillow.) Human perception, which functions by fusing simultaneous streams of sensory information, works on the assumption that if auditory and visual stimuli occur in proximity—close in both space and in time—they must be caused by a single source, the one you see. So when we watch lips moving in sync with an unrelated sound, our brain simply denies the confusion, the strange coincidence of these two events, and instead processes them as though they were one very normal speech act. Thus, a ventriloquist can modulate his voice to make it sound near or far, as though it were muffled in a box, or gurgling up from underwater, but he doesn’t actually “throw his voice” in any particular direction; he just tosses it to the audience and they—their eyes, their brain—place it in the lips of the dummy."

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