Work Step by Step
It depends on what is meant by "looks at" it. If somebody uses an electron or a light beam, i.e., probes the electron, then its motion will be altered. If that person just passively looks at light after it has reflected from the electron, whether with one eye or two, then it is unaltered. Arguably, Heisenberg's uncertainty principle applies only to probing, but some physicists believe that any measurement, passive or probing, alters what is being measured.