We present evidence that smiling is positively associated with positive affect in women and negatively associated with negative affect in men. In line with Vigil's model, we propose that, in women, smiling signals warmth (trustworthiness cues), which attracts fewer and more intimate relationships, whereas in men, smiling signals confidence and lack of self-doubt (capacity cues), which attracts numerous, less-intimate relationships.

Can the Internet reach beyond the U. S. college samples predominant in social science research? A sample of 564,502 participants completed a personality questionnaire online. We found that 19% were not from advanced economies; 20% were from non-Western societies; 35% of the Western-society sample were not from the United States; and 66% of the U. S. sample were not in the 18–22 (college) age group.

An imbalance is identified in social psychology between controlled experimental studies (which are common) and real-world, ecologically valid studies (which are rare). The preponderance of experimental studies (which provide mere existence proofs and lack realism) helps fuel social psychology's fault-finding focus. Laboratory experiments and ecological studies should be pursued jointly to examine social life in the real world.