McComb suggests that the purr-cry may subtly take advantage of humans' sensitivity to cries they associate with nurturing offspring. Also, including the cry within the purr could make the sound "less harmonic and thus more difficult to habituate to," she said.
McComb got the idea for the study from her experience with her own cat, who would consistently wake her up in the mornings with a very insistent purr. After speaking with other cat owners, she learned that some of their cats also made the same type of call. As a scientist who studies vocal communication in mammals, she decided to investigate the manipulative meow.
My cats wake me up by yelling in my ear, if you call that manipulative. Hurling them off the bed seems to be no deterrent.
I suppose we have to shift this topic to reading in some way. Do you have a favorite literary cat? I nominate Christopher Smart's Jeoffry.