Scientists studying brain process involved in sight have found the visual cortex also uses information gleaned from the ears as well as the eyes when viewing the world.

They suggest this auditory input enables the visual system to predict incoming information and could confer a survival advantage.

Professor Lars Muckli, of the Institute of Neuroscience and Psychology at the University of Glasgow, who led the research, 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 conducting five different experiments using functional Magnetic Resonance Imaging (fMRI) to examine the activity in the early visual cortex in 10 volunteer subjects.

In one experiment they asked the blindfolded volunteers to listen to three different natural sounds - birdsong, traffic noise and a talking crowd.

Using a special algorithm that can identify unique patterns in brain activity, the researchers were able to discriminate between the different sounds being processed in early visual cortex activity.

A second experiment revealed even imagined images, in the absence of both sight and sound, evoked activity in the early visual cortex.