This option is not available inside computer configuration preference settings, only for the user side.
If you create a preference package inside Computer Configuration and look at the Common tab, you will see this option is grayed out.
When selected, this causes Group Policy to apply these preference settings from the security posture of the user who is currently logged in. This is different than typical Group Policy processing, which always runs under the SYSTEM account. While SYSTEM has the ability to do pretty much whatever it wants within the operating system (this is why Group Policy is so powerful!), there are some cases where you might want the preference setting to apply from the user's context, and this setting is your method for accomplishing that.