London:
Approaching footsteps, someone following you? The sound of something getting closer actually increases the sensitivity of your brain's visual part; it's like you are seeing in the dark, says a new study.
Researchers at Glasgow University have found that "looming signals" -- sounds that indicate that something is approaching rapidly -- are due to changes in the visual cortex which occur before people are even conscious of the sound, suggesting the response is hard-wired in brain.
They played 15 volunteers a selection of sounds, some of which sounded like they were approaching, while others seemed to be receding or stationary. At the same time, they used transcranial magnetic stimulation to excite the visual cortex at the back of the brain.
All the sounds made the volunteers more likely to see phosphenes during TMS, but the looming one had by far the strongest effect, the 'New Scientist' reported.
Volunteers saw phosphenes in 70 per cent of trials in which the looming sound was played, compared with 50 per cent when the sound was stationary, 45 per cent when it's receding and 36 per cent when no sound was played.
"The visual cortex is responding to non-visual stimuli," lead researcher Vincenzo Romei said.