The personalized results don't come up for each search that you do. The way you know that they have been personalized is by seeing down near the bottom of the page
"Personalized based on your web history. More details"
When you click on more details, you get the following:
When possible, Google will customize your search results based on location and/or recent search activity. Additionally, when you're signed in to your Google Account, you may see even more relevant, useful results based on your web history.
The following information was used to improve your search results for (key word):
Recent Searches: You or someone else recently searched for (key word) using this browser. Learn more
Web History: One or more items in your Web History were used to improve search results.
Manage Web History:
Remove Web History from my Google Account If you're curious, you can see what a search for (key word) looks like without these improvements.
The 'More details' link on your search results page can be used to display this page for approximately 30 minutes, after which it will no longer show this page.
So it looks to me like you don't have to be logged into your Google account to have the browser history affect some of your serach results.