A pretty face makes more of a difference than you might think. See what you think of this:
51 women signed up for a study on communication. They would speak to an unknown man on the phone and chit chat about the weather, hobbies, etc. The women knew nothing of it, but the men who would make the calls were given a biographical profile and a picture of the women they would be calling. Well. . . that’s what they thought. The profiles were accurate, but the photos were fake. They were specially selected photos: some were of extremely beautiful women while the other half were photos of more ordinary women. After seeing the bios and photos, but before making the phone call, the men were asked to fill out an impression questionnaire.
Not surprisingly, the men who had photos of beautiful women believed they would speak to women who were sociable, poised, humorous, and socially adept. The men who had photos of more ordinary women expected to speak to unsociable, awkward, serious, and socially inept. They had made their “diagnosis” and set their expectations before even speaking to the women.
During their conversations, the men had a hard time seeing the women in any other way. They naturally noticed the characteristics which supported their original assessments and ignored (or didn’t notice) the characteristics which deviated from their perceptions. Their bias’ were brought into the conversations.
Here’s where it gets interesting. The researchers recorded the phone conversations and took the men’s side of the conversation out. A third group of people who knew nothing of the study or it’s participants, were then asked to listen to the recordings of the women. Listening only to the women, this group was asked to fill out the same impression questionnaire that the men filled out earlier. They rated the women the same way the men did. They based their impressions off the voice of a one-sided conversation while the men had based their impressions off of a fake photo.
The expectations of the men not only influenced their perceptions of the women, but also influenced the subtle nuances of the conversations. The men were unconsciously sending out “beautiful” cues. The women subconsciously picked up on the “beautiful” opinions that the men had of them and they reacted similarly. Being thought of as beautiful, made the women believe they were beautiful and they acted as such. The third party group could hear the beauty in their voices 
because these women believed they were beautiful. Although some were actually very average in appearance, they were still seen as beautiful based upon the confidence and beauty in their voices.
Expectations matter. They change our own perceptions. They change others. They change the world.
Expectations matter.
PS – This experiment is described in the book Sway by Ori and Rom Brafman.