Google is considering allowing users of its search engine to tinker with query results by re-ranking them and commenting on them.

The company has already run public tests on its search-results pages that contain up and down arrows next to listed links, as well as buttons that allow users to append comments to results.

"At this point, I can't say what we expect from this feature; we're just curious to see how it will be used," wrote Ben Gomes, a Google Distinguished Engineer, in the company's official blog on Tuesday.

A screenshot of one of these test pages also shows "x" buttons next to results to apparently remove them from view, although this isn't addressed by Gomes.

Should Google decide to incorporate these as default features, the change would be a significant step by the company in giving people power to interact with its search-results pages.

There are a number of customization and personalization options that Google grants to users who open a Google account, such as keeping a log of their search and browsing activity via a service called Web History, as well as bookmarking and annotating site links with a service called Notebook.

However, in this test, the new functionalities apparently would be available to any user, not just those who are signed in to their Google accounts. The screenshot resembles a test described in a Google Labs Experimental Search page, although the experiment requires users to sign in to their Google accounts. It is not currently listed on the main Experimental Search page and is described as probably available for only a few weeks, so it is not clear whether it's still available for testing.

Google has often been criticized for having a search engine that depends too much on mathematical algorithms while giving little room for users to offer feedback and contribute to the process of rating, ranking and evaluating results. These knocks have become more and more common as the popularity of Web 2.0 services has grown, since they all champion the building of user communities.

As a reaction to the Google approach, a variety of search engine projects have emerged over the years that attempt to give people more participation, such as Jason Calacanis' Mahalo, Yahoo's Delicious social bookmarking service and Jimmy Wales' Wikia Search.

At Wikia Search, for example, anyone, whether registered with the site or not, can add, delete and rate search results, as well as edit the content of a search result URL by modifying its headline and description. In true wiki fashion, changes are reflected immediately and don't go through an approval process, counting on the community to police itself and establish, at least in theory, its collective wisdom.

Google declined to comment further about Gomes' posting. "Unfortunately, because the examples he provides are still only experiments, we cannot talk in length about how they work. If we end up rolling out this experiment for all users, we would definitely be able to talk in more detail. Right now we are experimenting with a number of factors so we can't really explain how the final product would work," a Google spokeswoman said via e-mail.

Thus, it's not known whether Google would factor the rearranging of results by users into the overall computation for ranking results for those specific queries. It's also not clear whether search result comments would be made available to anyone to read.

In the posting, titled "Search experiments, large and small," Gomes presents several other examples of public tests that Google has run on its results page.

Unlike the test to re-rank and comment on results, which is visually prominent, others are subtle and hard to notice, such as slightly varying the amount of white space between one result and another, or making a symbol look more or less thick.

The bottom line, wrote Gomes, is that "we test almost everything, even things that you would think are so small that we could not possibly care -- nor could they possibly matter. In fact, small changes do matter, and we do care."