I noticed that when I hold the control key at the screen where you select a boot disk (the screen obtained from holding down option at startup), the straight arrow below the selected boot disk turns into a circular arrow (similar to the Time Machine icon). I clicked this circular arrow thinking it would take me to the recovery partition, but the computer simply booted seemingly normally instead. What did the circular arrow do differently than clicking the regular, straight arrow?
It makes it the main boot disk so it will continue to boot from that disk. It's equivalent to the Startup Disk preference pane in System Preferences, only done in a different place so you don't have to boot into OS X.