There now appears to be a staggered vignetting to these photos, so I don't think I explained myself very well. I meant increase the contrast over the whole photograph, rather than just the background.
If you have a look in your gallery, you'll see that the first three thumbnails have a overall greyness to them, whereas the forth image 'the gaze' has the blacks as black. This might be what you intended, so please disregard my comments, if this is the case.
p.s. There is a little dust spec on the top of the beret of the second photo that you might want to clone out.