Norton Insight, Scan Performance Profiles

My copy of the latest NORTON360 -2010 has Norton Insight, with a drop-down menu"Scan Performance Profiles".  The 3 setting choices on the drop-down are: 1-High Trust 2-Full Scan 3-StandardTrust

I'D LIKE TO KNOW WHAT KIND OF CHANGES RESULT IN USING THE THREE.  IS FULL SCAN A HIGHER TRUST THAN HIGH OR STANDARD, OR WHATS UP?

To get there, Open Norton360 > Click on "Tasks"  >  On the right - . Under 'PC Tune-up Tasks', select  "Run Norton Insight".                        See Image attached.  Anyone who knows about this, please reply.

 

thanks