These, as one might guess from the name, allow you to to see the heat signatures given off by peds, cars, and whatnot. By selecting them from your item list and pressing circle to equip (or unequip later), the screen turns a rather psychedelic set of blue, purple, pink, and red hues; with blue being cold and red being hot, of course. After equipping the goggles, you're free to switch to another weapon so as to freely take out enemies you couldn't have seen otherwise. Naturally, they're best to use at night when it's hard to see otherwise, but even then they're still better suited to longer range combat. Moving about with these on can be somewhat tricky at times due to cooler landscape/building objects blending together with the ambient background heat (or lack thereof rather).