That panel, introduced about a year ago, has been until now closed by default, and users have had to click on the "Show Options" link below the search box to open it up.
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The panel's menu of search options, which include the ability to filter, narrow, and slice-and-dice results according to various criteria, is also getting an upgrade.
For example, the options to filter results by their type, such as images, videos, news, or books, will not always be listed in the same order, but rather arranged so that the filters that Google determines are more appropriate for the query appear first.
The search options panel is also gaining a new section, called "Something Different," which will list a new type of query-refinement suggestion: topics that are broadly related to the query.
The "Something Different" section is intended to complement the existing query-refinement suggestions that appear at the top or bottom of the result page's center panel and which are more closely tied contextually to the original query.
For example, a query for the rock group Rolling Stones will trigger "Something Different" suggestions like other rock bands and artists such as Pink Floyd and Led Zeppelin, while the center-panel suggestions will be "Rolling Stones songs" and "Rolling Stones pictures."
On the main Google.com page, users will notice a slight change to the Google logo on top of the search box: the rendering of the word "Google" has been simplified by eliminating the outline shading of each letter.
Google went through a lengthy testing process before settling on making these changes, said Patrick Riley, Google's technical lead for Web search.
"We're definitely well aware that small changes we make can have a high impact on how people use the site," he said. "We're happy with the results based on all the different forms of testing we've done."
A major goal of implementing these changes is to offer people a more consistent experience across the different Google search engines, Riley said.
To that end, for example, the left-hand column search options panel will be open by default in most Google search engine result pages, including those for general Web search, Image search, Books search, News search, Video search, and others, with the exception for now of Maps search and Shopping search.
In addition, the panel's section to filter results by type, whose options will be dynamically sorted for each query, will nonetheless remain the same for a query across the different search sites.
"We really want to unify the search experience," Riley said.
This builds up on the ambitious and ongoing universal search project, unveiled about three years ago, through which Google collates different types of search results on a single results page, mixing links to pages, videos, news articles, blogs, photos and the like depending on the query.
That way, the search experience has become more organic and less segmented than in the past, when images only showed up in the Image engine, articles only in News search, and so on.
"We started down this path with universal search," he said. "As universal search has gotten better and better, search has become one thing people interact with."