Vertical or Horizontal Slider for History version?

Question

I'm working on a History Control Version of a web app. It will be kind of Time Machine style, where you can move a slider to go from past to present (or the other way too) and immediately see an image of that version.

Now the question is about the slider. Logically for me is that the slider should be horizontal going from left to right to go from Present (at the left) to Past (at the right). But when I see Time Machine (apple) they use vertical slider (see image) where the present is at the bottom.

What are your thoughts about this? Does it really matter? And what are your thought about -if the slider is horizontal- the present is at the left and past in the right, and -if slider is vertical- the present is at the bottom.

Thanks

Answer 1

Obviously you could expect that some of your future users will be Mac users who know Time Machine (~9% OSX worldwide users, Statista January 2015, in German) therefore could know how to interpret your design. (I wouldn’t rely on it. Who’s doing backups anyway!)

For me, thinking about ways to display timelines, I would assign the Present to the left and Past to the right side. You only have to remember the timelines displayed in history books in your school where it goes from Neanderthal to Neoclassicism, reading the line from left to right.

But to give some direction, I conducted short user tests presenting both patterns and which show that 80% would expect to see the Present in front in a horizontal presentation and 75% on the left in a vertical presentation.