Colgate dental floss

This advertisement shows a man and woman smiling for a photo. The image forces the audience to draw attention to the man's teeth in both photos. However, in each photo there is something else that is unusual. For example, in the first photo, the woman has an extra finger on her hand. This advertisement therefore provides an example of association, in that the issue (a problem with the man's teeth) is linked to another negative issue (i.e. an extra finger). The main object (the teeth) has been linked to another object on irrelevant attributes. Research supporting this technique can be found by Warlop & Alba (2004) who found that visual similarity can act as a persuasion tool. In the case of this advertisement, visual similarity between teeth and fingers helps to show the audience that these are both similar problems. It emphasises how important having clean teeth is, and makes the audience self-conscious.
This advertisement also uses shock to increase attention. Shocking advertisements create stronger feelings among the audience and significantly benefits memory-it has been found that participants are much more likely to remember shocking advertisements than advertisements that are not shocking (Dahl, Frankenberger & Manchanda, 2003).
This advertisement also uses decoys (an inferior option). In this case, the inferior option would be to have an extra finger. Research has found that adding an inferior option to a choice set will make the consumer choose the dominant option (Huber, Payne & Puto, 1982).
Associative casting and avoidant miscasting are also used in this advertisement. Most people would not want to be connected with an undesirable person, such as the man in these photos. For example, Cooper & Jones (1969) found that when participants interacted with an obnoxious partner their attitudes changed so that they were dissimilar to their partner's attitudes.

Warlop, L. & Alba, J. W. (2004). Sincere flattery: Trade-dress imitation and consumer choice. Journal of Consumer Psychology, 14, 21-27

Dahl, D. W., Frankenberger, K. D. & Manchanda, R. V., “Does it Pay to Shock? Reactions to Shocking and Nonshocking Advertising Content among University Students”, Journal of Advertising Research, September 2003, pp. 268-280.

Huber, J., Payne, J. W., & Puto, C. (1982). Adding asymmetrically dominated alternatives: Violations of regularity and the similarity hypothesis. Journal of Consumer Research, 9, 90-98.

Cooper, J., & Jones, E. E. (1969). Opinion divergence as a strategy to avoid being miscast. Journal of Personality and Social Psychology, 13, 23-30.