Google tracks every link you click on when you search by sending you to a tracking url, and then redirecting you to the real website you clicked on. Google is able to track you regardless of whether or not you have disabled cookies or if you are running in incognito mode. Every click can be (almost) individually tracked.
Google is tricky because if you hold your mouse over the link it shows the real website url in the bottom left corner. But if you click on the link you will be sent to the site you requested with a very descriptive tracking url in tow.
For example, if I type in Google Search, “lessgoogle.com,” you can see in the screenshot that www.lessgoogle.com is displayed correctly there at bottom left. But if you right click on the link and Copy Link Address, the result is something quite different:
To fix this you can install a Greasemonkey script called Google Result-Privacy. Chromium and Chrome have limited native Greasemonkey support, and Firefox requires a plugin.
Now when I copy the link when searching for “lessgoogle.com” I get:
Of course, incognito mode disables all extensions so your Greasemonkey script will be disabled and you will get the tracking link back again. However, if you run in your own profile, extensions will still operate.