Okay both of these posts are right/wrong.
Here are the "requirements" to say your playing a game in "full settings"
Native resolution of your monitor being used.
Full settings is setting a game's graphics options such as: details, models, shaders, lighting, distance viewed, Anti-aliasing, and anisotropic filtering them to the maximum.
For example: Ill show a picture of AION (Mmorpg) and Left 4 dead with "Full Settings)
(I am forcing CCC to run at x8 AA (Anti-Aliasing) and x16 AF (Anisotropic filtering)
Incase your curious: Anti-Aliasing is software-made smoothing of jagged edges, this helps give a smooth image (less 2d more 3d).
For example: Looking at a Ps2 game Ps3 or 360 game. Ps2 appears edgy, not smooth, and jagged because of it's poor anti-aliasing (although FFXII really pwned with AA). While Ps3/Xbox 360 games are better smoothed, this is because of higher AA.
Anisotropic Filtering is software-enhanced far viewing background. Unlike objects which are often loaded with complete quality at far sights, anisotropic filtering deals more with background details and enhancing the quality on backgrounds that are far away.
For example: Im sure you remember in perhaps Playstation/Ninendo games that backgrounds where often like "pictures." Anisotropic helped change this by added higher quality, of course this takes it's toll on the GPU.
AION Max settings: Monitor 23" native resolution: 1920x1080
Left for Dead Max settings; Monitor 23" Native resolution: 1920x1080