[R]esearchers differentiated between arousal, objectification, lack of credibility, and dehumanization. Sexualized imagery can cause all those things, but it was specifically the dehumanization that correlated with the loss of support for PETA’s cause. So for instance, a man could be aroused by an ad, but that alone didn’t turn him away from the cause that was being advertised. That only happened when the woman in the ad was dehumanized, as measured by a series of “uniquely human” traits, like being capable of thought.
–Skepchick on sex doesn’t sell… with science!