Facebook's news feed employs a 1-column layout, whereas Google+ employs multi-columns, depending on the width of the browser. (It appears it's between 1-3 columns). Pinterest have many.
Are there any studies or guidelines that suggest strengths / weaknesses of this difference, and when one should favour one approach over another?
i.e., do users get confused or overwhelmed by the multiple columns?
If you're going for objective performance measures, a study reported that for on-screen text, longer line lengths (approx 100+ words) supported faster reading and medium line length (55 characters) for better comprehension.
However, subjective measures indicate that people prefer a more moderate line length. On columns: "a single wide column is read faster, but narrow multiple columns are preferred". Multiple columns are actually judged as easier to read and contribute to the screen being judged more organised and offer visually interesting texts.
References:
Dyson, M.C. How physical text layouts affects reading from screen. Behavior & Information Technology 23, 6, (2004), 377-393
Braganza, C., Marriott, K., Moulder, P., Wybrow, M., & Dwyer, T. Scrolling behaviour with single- and multi-column layout. WWW '09, (2009), 831-840.
If the items in the timeline are arranged in chronological order, that order should immediately obvious in the layout. Since time moves in one direction (in western culture at least), your layout should also move in one direction. A single timeline cannot be presented over multiple columns without inducing a level of confusion. If the columns fit the current view, you could have the timeline flow from one column to the next however.
That is not what Google Plus is doing though. Since discussions can run in parrallel, they've decided that they can introduce a little ambiguity in the way the discussions are sorted. This allows them to fill the screen in a an attractive way. Presentations that move away from the list view offer more at a glance. This fits Pinterest since that's all about collections that aren't necessarily ordered in any way. Chronological order also isn't all that important in social media either. Facebook also mixes a level of relevance into it's sortation and that's fine too. Newspapers also aren't chronological (but since it's today's paper you know it's recent news).
I don't have any research specific to this situation. However, I do know from experience that for a list of (future) events people vastly prefer to just have a chronological list. So if your interface is about finding an event that happened at some point in time, be sure to just present stuff in a single list.
