A large majority of Google users are opted in for the Personalized Search (Beta) program right now. But what a lot of those users don’t know is that being opted in for this program actually hinders their search results.
I’ve taken a few screen shots to show you what I mean.

This is an example of search results turned on. Meaning that search results are slightly effected by your activity while using Google. Of course when ever you’re logged in, Google knows where you’re going, what you’re doing, how you’re buying, everything.
You know those sweet tasting things called cookies? Yeah, Google has those. Your account has those, everything has them. So anyone can track where you’re going.
Let’s take a look at what it looks like to not be using personalized search.

This is an example of what it looks like when the personalized search results are off. Notice the difference? Some searches do provide different results, but some searches don’t.
I feel that these personalized results are giving sites that you visit often a little higher weight in the algorithms when displaying results while opted in to personal results.
Google’s presentation of how this program is used has been portrayed very poorly and I don’t think people actually realize how their search results are being displayed. Yes, I do realize that the vast majority don’t care about the algorithm and just want their search results, but there are some of us who do care how it works.
