Almost all of the degrees of freedom come from head motion and muscle artifact. EEG is very sensitive to facial muscle artifacts, and when you actually record EEG the patients have to keep very still.
The larger problem with the Emotiv EPOC headset is that the EEG sensor locations it provides do not match up to where "real" Brain-Computer Interface (BCI) research is focused. So even if you wanted to do control by "pure thought" alone the best-known areas of the brain where these signals are located are not measurable by the Emotiv EPOC.
Electrode placement is based on an international standard called the "10-20" system:
Most BCI applications focus on "imagined" movements around the right arm or hand, left arm or hand, and feet. The parts of the brain which produces electrical signals when neurons related to these extremities fire are located in the C3 and C4 sections of the top of the scalp in the diagram at that URL. Another important location is the "Cz" sensor at the exact top of the crown.
Unfortunately however, the key Cz, C3, and C4 electrode locations (going by the 10-20 scale) right/left/feet motor control are not available on the Emotiv hardware. Instead their hardware provides electrodes in the following 10-20 locations:
AF3, F7, F3, FC5, T7, P7, O1, O2, P8, T8, FC6, F4, F8, AF4
My understanding, based on discussions with Emotiv, is that they designed their headset with as many unique channels of information as possible, at the best price/feature ratio, which would fit the most number of potential users in a one-size-fits-all form factor. This last restraint prevented them from Cz, C3, and C4 because the exact locations from user to user were not consistent enough to be relied upon in a consumer setting (their target market). Locations for an adult would not be the same as an adolescent user, and getting the locations lined up precisely is "too hard" for the casual or non-technical public.
So in other words, if you want as fine-grained control by thought alone as the current state of technology allows, you'll have to wait for a updated EEG headset model from Emotiv or another manufacturer - or of course learn how to build your own from the .