There is a way to change your search settings so that past searches are deleted and search history is turned off. Google will still collect the data, but it will be for internal use only and after 18 months be partially anonymized. Law enforcement agencies will still have access to the data. The Electronic Frontier Foundation has provided a guide to remove your Google search history at: https://www.eff.org/deeplinks/2012/02/how-remove-your-google-search-history-googles-new-privacy-policy-takes-effect
Of course if you are not logged in to any Google services while searching, then none of the results wouls be directly linked to your accounts.