There are as far as I'm concerned two key issues to address when using a SSO (Single Sign On) -concept.
- Accessability: The sign in/registration page should clearly show that the users may sign in using their Facebook account.
- Credability: The button/link in addition to the overall page should convey credibility.
There is an A/B-test with the use of Facebook SSO conducted by Gameground. (Scroll down to "Social Media Click-Through")
They conducted a test with the use of two different landing pages which also consisted of two different Facebook connect buttons.
Landing Page A
The first example used the conventional Facebook-styled connect button, the same as in the OP but with a different text saying "Sign in with Facebook" instead of "Connect with Facebook". The button is quite small in comparison to the main sign in-button that says "GET STARTED" but should still be quite easy to spot.
Landing Page B
The second landing page has discarded of any alternative sign in and now Facebook looks to be the only way. The button follows the look and feel of Facebook but in contrast to the previous button it lacks the Facebook logo.
The page layout overall has also changed and there's more emphasize on what you can expect if you connect to Gameground.
This version (B) produced a 60% higher conversion rate over the full funnel conversion goal.
So there we go, a blue button with no logo will raise your conversion rate!
Or is it that simple...?
I believe there are more aspects than merely the type of button that happened to be present at each version. Sure, in page B it's bigger and centred, clearly catching the attention of the visitor. But I'm sure there are more aspects than the type of button that made version B successful. I'm sure (within my own reasoning) that if version B had the same styling of the connect button as version A had, it would still have been successful.
The success. in my mind, lies in clearly communicating to the visitor what perks they may gain by joining Gameground.
Even though there was a difference in conversion rate in the examples above using different Facebook connect-buttons, I don't believe the type of button had too much to do with it. They both breathe the Facebook brand, the only distinction is that version A had a Facebook logo, and I'm not ready to suggest that the logo alone scared potential users off.
So to summarize.
- Use a button that clearly breathes Facebook in style, blue background with white text in Klavika Bold -font (the closest us mortals get to the Facebook font which is developed by Joe Kral). This way you convey credibility since the visitor will associate your site with Facebook which he/she already confides in.
- Make it so that the landing page clearly communicates all the perks
the user can expect if they join.
- Have the connect button show clearly, have version B in mind.