Scientists studying brain process involved in sight have found the visual cortex uses information gleaned from the ears as well as the eyes when viewing the world.
Professor Lars Muckli, of the Institute of Neuroscience and Psychology at the University of Glasgow, who led the study, said: "Sounds create visual imagery, mental images, and automatic projections.
"So, for example, if you are in a street and you hear the sound of an approaching motorbike, you expect to see a motorbike coming around the corner. If it turned out to be a horse, you'd be very surprised."
The study, published in the journal Current Biology, involved five experiments to examine the activity in the early visual cortex in 10 volunteer subjects.