Smith, G. H., and Engel, R. (1968). Influence of a female model on perceived characteristics of an automobile. Proceedings of the 76th Annual Convention of the American Psychological Association, 3, 681–682.
Described in D. A. Lieberman (1982), Human Learning and Memory, Cambridge University Press.
Smith and Engel (1968) showed 120 men a picture of an automobile. For half the subjects, the photograph showed only the car, whereas for the other subjects a sexy redhead, dressed in black lace panties and a sleeveless sweater, was standing in front of it. After examining the picture, participants were asked to evaluate the car on several dimensions. Those who saw the car with the attractive female next to it rated the car as significantly more appealing and better designed. They also estimated it to be more expensive (by an average of $340), faster, and less safe. When the authors later asked a subset of the participants if their ratings had been influenced by the presence of the model, however, 22 out of 23 denied it. One respondent claimed, “I don’t let anything but the thing itself influence my judgments. The other is just propaganda.” Another commented, “I never let myself be blinded by advertising; the car itself is what counts.” Thus, although the model’s presence clearly altered the participants’ ratings of the car, virtually none believed that he had been affected.
I have to find a copy of this study. It could provide a good example of: 1) experimental design; 2) involuntary bias; 3) the influence of advertising.
Another related work is: K. Debevec and J. B. Kernan, “MORE EVIDENCE ON THE EFFECTS OF A PRESENTER’S ATTRACTIVENESS: SOME COGNITIVE, AFFECTIVE, AND BEHAVIORAL CONSEQUENCES”, Advances in Consumer Research, vol. 11, pp. 127-132, 1984.