An approach to a common situation that seems entirely natural now (though not necessarily pleasant, comfortable or in any way a good idea), but was not always the case.

Nancy Martha West, talking about the marketing of the first Kodak cameras in the BBC's Genius of Photography series:

...People are encouraged through Kodak ads to smile at the camera rather than make it a serious enterprise...

As someone who loathes putting on a rictus grin for the camera, I'm pleased to find out that it was just a marketing wheeze and I can go back to the inscrutable deadpan look.