1. Engagement particularly with richer content.
The evidence concerning the change in engagement is mixed.
Evidence of increased engagement
This study suggests some positive impact for marketers - Simplymeasured.com
- 14% Increase in Fan Engagement
- 46% Increase in Content Engagement
- 65% Increase in Interactive Content Engagement (Video and Photo)
Evidence of mixed or poor engagement
This one shows mixed results for engagement and pageviews: Attention USA.
And this from Mashable: Fan growth slowed after timeline introduced ... but did it pick up again after people got used to it?
This study suggests little impact: allfacebook.com
However here is a rebuttal: jonloomer.com
(Basically proposing that timeline could impact on the things that matter - more fan visits and more engagement with apps)
I can't locate it now, however I recall seeing another report that found a decrease in interaction with wall posts (of the user's friends) via timeline. What some consider the core purpose of Facebook from a user point of view. However this is far harder to find as the emphasis has been on brand marketing impact for logical reasons.
Bottom line: The results seem positive but there isn't a strong consensus yet
2. Encouraging a different level of sharing and expression
From a FastCompany article interviewing Timeline's designer:
Wanted to convey feeling...The feeling of telling someone your life story, and the feeling of memory--of remembering your own life....
Also from one of the designers (Nick Felton, who is famous for infographics)
Time is the most universal framework across cultures... It’s a shell on which users themselves can define what they want to highlight.
Facebook wanted the Timeline to be a place for self-expression: A way for users to reveal who they are and what their lives are about.
Self-expression or curating your space creates value for Facebook. A richer space with more cues enables more, deeper sharing. Facebook's lifeblood.
Finally a clue could be in one of it's designers Nickolas Felton. He previously worked on Daytum - quantified self / personal stats company - before being acquired by Facebook.
Could it be that Timeline is a step towards greater capabilities in personal tracking too?
This article in Social Media Today complains that,
Timeline switches the overall metaphor from Facebook as sharing hub to Facebook as historical record keeper.
This may be true. However in my observation much of the 'right now' interaction happens within the news feed. The timeline as a record keeper, as a place to curate and build a picture of yourself is less about 'right now' and more about giving your brand/yourself context. Telling your story. Other features like chat, newsfeed, likes, and mobile could be more useful for 'right now'.
Remember: UX is central to anything that encourages, enables or discourages certain behaviours.
Edit. Additional information found.
I came across this from Adam Mozeri a product designer for Facebook. He describes the change as data driven. They discovered their previous layout caused a limitation...
“What we were doing here is we were optimizing for a local maximum. Within this framework, there was only so much traffic we could funnel to applications. And what we needed was a structural change. Our premise was off. Our interests were leading us down the wrong path. We didn’t realize it [...] we were optimizing for something locally, and we needed to be somewhat disruptive to sort of get out of it.”
"...you’ll see us continue to make big changes that you’ll be like, “How is this good for data?” or “How is this good for anybody?” but there’s a reason behind it. Usually it’s either because we believe that this is where the market is going, or it enables a product that’s gonna come later, or we’re worried about being stagnant and we wanna continually innovate...."