The above image is part of Dove's on-going real beauty campaign, which was was created to provoke discussion and encourage debates about a wider definition of beauty. This advertisement provides an example of the persuasive technique of social consensus (bandwagon), which is based on the idea that the more it appears others are doing something or support a position, the more likely it is for others to join in. The idea behind the campaign is that if these women of different sizes, heights, races, hair colour etc all believe and support the campaign and consider themselves beautiful, you should too!
Research by Milgram, Bickman & Berkowitz (1969) provide evidence for the bandwagon effect. The aim of their experiment was to investigate the relationship between the size of a stimulus crowd and the response of the passers-by. The subjects were pedestrians on a New York street on which a group of confederates were positioned looking up at a building window for 60 seconds before they dispersed. The size of the confederate crowd varied in conditions from 1- 15 people. They found that passersby copied this response, with the level of conformity increasing, at a lower rate, with each additional confederate looking up. Also,a larger number of passersby partially adopted their behaviour, not by stopping completely but by breaking their stride or looking up, again with the size of the crowd increasing the influence. The study concluded that the people follow the behaviours of crowds and that the number of people who will react to and join in on the behaviour of a crowd is related to the size of the crowd.
The figures shows that as the size of the stimulus crowd increased, so did the number of people who stopped and looked up. The basis behind this is that the larger the crowd the more likely it would seem that the members are attending to something of interest, in the case of the Dove campaign, the more people agreeing with them and joining their idea to redefine beauty.
Milgram, S., Bickman, L., & Berkowitz, L. (1969). Note on the drawing power of crowds of different size. Journal Of Personality And Social Psychology, 13(2), 79-82.