OCZ developed the NIA in conjunction with Brain Actuated Technologies Inc, who originated the technology for medical use. The NIA would be classified as a non-invasive one-way BCI since it doesn't require surgical installation and it only offers one-way communication with the computer. Thankfully, or perhaps disappointingly, instead of a Matrix style head-spike, you'll use a one-size-fits-all rubber headband.
The NIA works by detecting the natural biopotentials in the body using a set of three sensors attached to the front of the headband. Biopotentials are electric quantities such as a voltage, current or field strength, that are caused by biological chemical reactions. The NIA detects these quantities and principles of signal analysis are used to simplify these inputs into different frequency components which can then be assigned to individual computer commands.
The significance of this is that rather than "reading" or translating your thoughts, the NIA detects the most basic components that make up your thoughts; the electrical signals. This means that thinking "go left" probably won't have the desired result and the NIA is unable to translate thought commands like "duck" and "shoot" into computer inputs. Rather than commanding the NIA with direct thoughts, you will need to learn how to isolate and control the specific signals it can detect, in a similar way to how we can isolate and control the signal used to move a leg or flex a bicep. The advantage of this method is that once the skill has been mastered, navigation and control within a game should seem nearly as easy as controlling your own body, except without the tactile feedback.
However, the NIA isn't limited to biopotentials generated by the brain. The NIA is technically a 3-in-1 device. It is a combination of a simple electro-encephalogram, electro-myogram and electro-oculogram. In plain English that means it can detect biopotentials generated by activity patterns in the brain, muscles and eye, respectively. More specifically, the NIA is able to detect upper facial muscle movement and eye movement as well as Alpha and Beta brain rhythmic activity.
An unfortunate result of the way the NIA works is the user will not be able to pick it up and use it to anywhere near its full potential after a few minutes of practice. Much like touch typing (without looking at the keyboard), the basics can be learned within a relatively short time but it often takes months of practice to master and reach your full potential. The first time you try to use the NIA, chances are the only one of its numerous controls you will be able to willingly effect in any way are the muscular signals. Retinal signals and brain signals are more difficult to learn and master. Thankfully, practicing with the NIA isn't nearly as dull as practicing touch typing, since we found the best way to practice is to simply game with it as much as possible (as if you needed another excuse).
Another characteristic of the NIA is that different users will have different results. Some users, due to any number of reasons, will simply take to the NIA quicker than others. These characteristics of the NIA are unfortunate disadvantages that may push some people away from purchasing it. This is especially true for casual gamers who won't have the time or attention span to spend on this unique peripheral. However, the potential advantage should you persist through the long learning curve is the possibility of near-total immersion within a game well beyond anything possible with traditional input methods.