Most of us have heard some time the famous warning while travelling in UK´s London Tube: "Mind the gap", trying to prevent accidents inside the stations when trains are in the platform. This message is also present at other metro networks such us Paris, Hong Kong, Singapore, Athens... But during my last visit to London, I found interesting that while in peak hours, that pre recorded voice (performed by Tim Bentinck) comes from a human controller situated inside the plattform, just by the train, warning you not only to mind that gap, but also the options to exit the area, when the train is departing, connections between stations and so on. It wasn´t easy to catch one of these operators so close (YouTube, 30secs.):
Compared to the classic "Mind the Gap" pre recorded voice seem below the message changes completely (YouTube, 1:08min):
Trying to research a bit more about this topic I found several articles related to the psycology of warning messages and it turns out that, we human tend to pay much more attention to messages coming from human than from machines. As Marc Green states:
"Warnings often fail to change people's behaviour. Either the warning goes unnoticed, or, as increasingly happens, the warning is seen but ignored. For many years, designers focused their concern on sensory aspects of warnings: color, shape, location, pictures vs. text, size and so on. However, recent research suggests that effective warning design depends as much on the contents of the viewer's head as on the contents of the warning's message".
I completely agree with Green´s statement: Adapted messages and, above all, coming from a human voice in the right moment, are much more effective that warnings coming from a pre recorded box. Pre recorded warnings have always the same tone, voice and message: the more you listen to them the less attention you pay on.
As Marshall McLuhan once stated: "The medium is the message" by meaning that "the form of a medium embeds itself in the message, creating a symbiotic relationship by which the medium influences how the message is perceived".
More about the psychology of the warning messages can be found following these links: