Nedarim 25: Unwitting, Accidental Vows

Do people use their own language when formulating a vow? Or are they more likely to rely on a formula? What kind of pitfalls are there (or potentially so) in one's own language? Also, a new mishnah, on unwitting vows. That is, when one makes a statement that is based on a mistaken premise. Plus, R. Akiva's innovative statement about vows - that nullifying a vow in part nullified it in full.