You can't exactly bounce photons off an electron to "see" it. I'm not sure, but I think the scientists are using some type of magnet the electron has to pass by, or "shield" that the electrons has to pass through. Otherwise, how would you detect it? Either one of these (even bumping a photon off it) disturbs the path of the electron. I don't know exactly why this would cause it to act like a particle instead, but it is not simply just "watching" an electron that makes it do this. It's interference.
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