Altering Speed Perception through the Subliminal Adaptation of Music within a Vehicle

We consider the potential for novel in-vehicle user-interfaces that alter speed perception at a subliminal level through the spatial adaption of music. In a fixed-base simulator, twenty-six participants drove on a motorway and were asked to maintain a speed of 70mph. At specific points, the speedometer was turned off. Music at a constant tempo was played throughout but periodically changed in balance from a 50:50 front:rear speaker split to a 25:75 ratio. Without the speedometer, participants drove significantly slower after the music had faded from the front to rear speakers (mean speed 71.5mph) compared to when no change occurred (mean speed 73.1mph). Post study interviews revealed that participants were not aware of alterations in the spatial positioning of the music. Such results suggest drivers naturally slowed when the music faded from front to rear speakers in an unconscious attempt to re-envelope themselves within the sound bubble.