Google “Sometimes” Case Sensitive When Searching + The Rest

Over the past several months, we have been hearing report after report that Google is changing the search results based on the case sensitivity of the search phrase. In May, Matt Cutts of Google was confused by my reports of case sensitivity as well but never really confirmed or denied the reports. In addition, according to the official Google documentation, Google is not case sensitive. Yes, Google says, “searches for george washington, George Washington, and gEoRgE wAsHiNgToN will all return the same results.”

Last night, during the Webmaster Help Group chat session, the question was brought up in the Q&A box. John Muller of Google was the first Googler to admit that Google may, on some occasions, take case into account on a search result. I have posted the Q&A transcript, so let me quote it for you:

Robert Longfield – 5:11 pm
Q: Does google differentiate between searches in lower case and searches with proper capitalization?

John Mueller – 5:28 pm
A: We may take this into account if we can recognize that it is relevant to the query.

This clearly states that Google is case sensitive and that the Google documentation is wrong or outdated.

I figured I would do a chart to document how each search engine handles case sensitivity. So let’s use Google’s example of george washington, George Washington, gEoRgE wAsHiNgToN, and GEORGE WASHINGTON to compare for each search engine:

As you can see, only Google is case sensitive. I have captured screen captures of the Google results for you all to see. Here is the lower case, here is title case, here is mix case, and here is all caps.

The case sensitivity is very slight. It’s not that searching in all lower case only matches words in all lower case and so on. Instead, it’s just that using different cases can generate slightly different results. In my tests, the bottom result was different for two queries (that showed a book search result).

Just to be clear, I had personalized search off when testing these Google results.

Important Postscript: John from Google emailed me to let me know he was wrong and what I have been seeing for the past several months is not related to case. Here is what he said:

It looks like I may have been a bit too fast in answering that one :-). At the moment, as far as I know, we do not look at case sensitivity in web search. However, at some time in the future, we may decide to take it into account should we find that it is relevant and improves the quality of our results.

If you see differences at the moment, it is likely due to normal fluctuations and perhaps differences across datacenters. If you find drastic differences, it would be great if you could post them here or better, in the Webmaster Help groups so that we can investigate them appropriately.