In the elaboration likelihood model, if an advertisement contains an attractive person, would this be using the central route or peripheral route? I would guess it would be peripheral route, since people don't tend to think about if a person is attractive or not, but on the other hand, if the person does think about the person's appearance and finds them attractive, then it could be considered central.
Unless the advertisement is actually advertising the person's attractiveness directly, this should be a peripheral issue. Consider Wikipedia's description of the central route:
Thus the only circumstance in which a person's attractiveness should be a central route is one in which the advertisement's argument is about the person's attractiveness per se...I'm not sure I can even think of a good example of such an advertisement. Even beauty product advertisements (which are about the product, not the person) routinely appeal through peripheral routes by using supermodels with immaculately styled hair, wearing much more makeup than the object of the advertisement – not to mention expensive clothes and other fashion accessories – in idealized, studio-lighted environments. If anything, factors like these obscure the real efficacy of the given beauty product, because most observers will just be overwhelmed by the model's beauty and by the desire to emulate it, regardless of how little the product in question has to do with it. Again, see Wikipedia on the peripheral route: