Google's John Mueller said in a Google Hangout yesterday that there are no Google algorithms that specifically look at user actions on your web site and use that as a ranking factor. He said, "I don’t think we even see what people are doing on your web site." So if they cannot see it, they can't use it as a ranking factor.
The question came up at the 38:11 minute mark in the video:
I am webmaster for an information based website, when a user fills out a form, in a conversion like that will the algorithm deduce it as a positive ranking factor? Or a user spends time reading a blog article -- does that increase the authority of my website?
John's answer:
So in general, I don’t think we even see what people are doing on your web site. If they are filling out forms or not, if they are converting and actually buying something... So if we can’t see that, then that is something we cannot take into account. So from my point of view, that is not something I’d really treat as a ranking factor.But of course if people are going to your web site and filling out forms or signing up for your service or newsletter, then generally that is a sign that you are doing the right things. That people are going there and finding it interesting enough to take a step to leave their information as well. So I’d see that as a positive thing in general, but I wouldn’t assume it is something that Google would pick up as a ranking factor and use to kind of promote your web site in search automatically.
What about Panda and user experience factors? Well, there are other ways Google can tell if they think a user will be happy with your site. It is not based on user actions but based on your content and such.
Here is the video embed:
Forum discussion at Google.