People can sense a smile before it appears on the face The different responses suggest that genuine smiles are more valuable social rewards, said Dr Erin Heerey. She said: "These findings give us the first clear suggestion that the basic processes that guide responses to reward also play a role in guiding social behaviour on a moment-to-moment basis during interactions. No two interactions are alike, yet people still manage to smoothly coordinate their speech and nonverbal behaviors with those of another person. She said that polite smiles typically occur when sociocultural norms dictate that smiling is appropriate. Genuine smiles, on the other hand, signify pleasure, occur spontaneously, and are indicated by engagement of specific muscles around the eye. She said the study could help those who find social interactions tricky. She explained: "As we progress in our understanding of how social interactions unfold, these findings may help to guide the development of interventions for people who find social interactions difficult, such as those with social anxiety, autism, or schizophrenia."