You're hunched over the keypad at the ATM, trying to remember your PIN (was it Aunt Bess' birthdate backward, or your first girlfriend's phone number?), hoping the big guy behind you can't see what you punch in. What if, instead, the machine could recognize you all by itself? That's the idea behind an iris-imaging identification system produced by Moorestown, N.J.-based Sensar now in pilot testing at ATMs and bank tellers.

Iris-based identification, proponents of the technique say, has a number of features that make it highly accurate and broadly applicable. No two irises are identical-even an individual's left and right irises are different. The tangled network of connective tissue that creates the random patterns of the iris is protected from environmental influences because it lies inside the eye. And computers can adjust for light conditions and glasses or contact lenses. Iris imaging is thus finding its way into an impressive variety of applications-from computer access control to automated fare collection on public transportation to the identification of thoroughbred horses.