The postdoc doesn’t have impostor syndrome. Because to be an impostor, you have to expect some gain, and she’s expecting none. Also she doesn’t have any group of symptoms (see medical definition of ‘syndrome’). She only has one emotion, which is ‘Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaah!’*
* But then again, the expression may not be fully compositional, and the meanings of ‘impostor’ and ‘syndrome’ may have shifted quite a lot in the lexicalisation process. She decides to test this by comparing the vectors of the phrase and the vectors of its constituents, using a range of composition functions and 1000 random initialisations of her predictive model.