This problem is very challenging and the results are far from perfect.
to demonstrate shortcomings of popular rank-measures we create four tests: 1) we limit the data and produce a bad ranking prediction using limited part-of-speech analysis, 2) a slightly better rank predictions using LIWC word list (Pennebaker et al., 2001), 3) further improved ranker using n-gram approach, and 4) the perfect prediction, comparing the reference with itself.