Tulane University's own Melissa Harris-Perry on her September 1st program where they discuss the image of welfare users and its relationship to welfare support. She really tears it up. I'd like to see more people like her contributing to the public sphere.
For research on how conservatives (and yes, it was conservatives who did-and continue to do-this, at least at first) worked to create the mental linkages between welfare and people of color see Katherine Beckett's "Making Crime Pay" and Robert Entman and Andrew Rojecki's "The Black Image in the White Mind." Beckett discusses how conservatives worked to link non-whites with crime and welfare abuse in an effort to recruit southern democrats, working class whites across the country, and Catholic European immigrants in the Northeast. It worked, though it might be breaking up some today. Part of this was their "Southern Strategy." Entman and Rojecki talk about the way mass media and representations of blacks in sitcoms, news, and other programs helps encourage mental associations that link them with negative norms and values, and therefore, as undeserving. Both scholars offer abundant data that was systematically collected to support their argument. They provide data not only of media content (for Beckett it's media content and political initiatives), but also public opinions (Entman and Rojecki offer a nuanced scale of racial attitudes). They're both top notch scholarship and support exactly what Harris-Perry is saying.