Research in social psychology suggests that people do not always know why they do the things they do.  Many of our daily decisions seem to be driven by things we cannot put our fingers on.  Did you marry your spouse because she is bright, beautiful, and kind?  Or did you marry her because you were both born in the same month?

If the second explanation sounds crazy, consider research on implicit egotism.  Implicit egotism is an unconscious preference for things that resemble the self. In keeping with implicit egotism, my colleagues and I reasoned that if we like our names and our birthday numbers, we should also like people, places, and things that contain (or resemble) these names or numbers. In fact, Matt Mirenberg, John Jones, and I found that people seem move to states and cities whose names resemble their own first or last names (e.g., Cal moves to California, Virginia to Virginia). Likewise, John Jones and his colleagues found that people are more likely to marry others whose surnames match their own than chance dictates.

Moving from field studies to laboratory research, Jones also showed that people liked an attractive woman more than usual when her jersey number had been repeatedly paired (without their awareness) with their own full names.  We seem to like our names so much that we like anything that is merely associated with our names.  

Some behavioral scientists have been skeptical of such findings. It’s hard to blame them. Do we really make major life decisions based on unconscious associations to our names or birthdays?  One critic argued that the kind of associations we have about our names or birthdays, though real, can’t be powerful enough to affect major decisions.   If people named Smith marry other people named Smith at a higher rate than we’d expect by chance, it must be due to other forces.  For example, maybe people named Smith are more likely to be White than people named Johnson.  We’ve long known that people marry members of their own ethnic group more often than they marry members of other ethnic groups.                           

To address this concern, Mauricio Carvallo and I recently looked at both birthday-number matching and birth-month matching in marriage. Although African-Americans are, in fact, named Johnson more often than they’re named Smith, there’s no reason to believe that birthday months vary with ethnicity the way names often do. Thus, looking at birthday-matching rather than name-matching is a good test of implicit egotism in marriage. 

Mauricio and I observed both birthday-number matching and birth-month matching in every set of marriage records we could locate that allowed us to test this birthday-matching hypothesis. For example, in one large study, we observed a modest tendency for people to marry others who were born on the same day of the month as they were. Further, this modest bias became a 20% bias in people who liked their birthday numbers enough to have gotten married on those numbers. If Janelle was born on the 20th and got married on the 20th, the chances that her groom was also born on the 20th were 20% greater than we’d expect based on the chance distribution of birthday numbers.

Mauricio and I also observed implicit egotism in career choice.  Using recently-released 1940 U.S. census records, we identified all 11 of the common male career names (e.g., baker, painter) that doubled as last names. Our findings appear in the graph below. 

For each of these careers, men were overrepresented in that career when the career name matched their surname.  In the figure below, any value greater than 1.00 means that there were more people working in that career than you’d expect by chance.  Thus, a score of 1.40 for Baker means that people named Baker were 40% more likely to work as bakers than you’d expect based on the popularity of this career and the popularity of the name Baker.     

Surname-Occupation Matching Effects for Men with Common Surnames that Also Serve as Male Occupation Names. Source: 1940 U.S. Census.

Surname-Occupation Matching Effects for Men with Common Surnames that Also Serve as Male Occupation Names. Source: 1940 U.S. Census.

Using these same 1940 census data, we showed that these effects did not occur because people in different ethnic groups worked in different kinds of jobs.  The career-surname matching effect existed not only for both Black and White men considered separately but also for Black and White men whose education levels were kept the same.

Finally, our studies show that implicit egotism is, in fact, implicit—meaning nonconscious. Virtually none of the participants in our laboratory studies of implicit egotism have been able to report the true reasons for their preferences for things that resembled the self.  A lot of what we all do every day may be driven by subtle, unconscious biases that rarely make their way to our conscious minds.    

For Further Reading

Pelham, B.W., & Carvallo, M.R. (2015). When Tex and Tess Carpenter build houses in Texas: Moderators of implicit egotism. Self and Identity, 14, 692-723.     

Pelham, B. W., Mirenberg, M. C., & Jones, J. K. (2002).  Why Susie sells seashells by the seashore: Implicit egotism and major life decisions. Journal of Personality and Social Psychology, 82, 469-487.    


Brett Pelham is a social psychologist who studies the self and social cognition.  He is also an associate editor at Character & Context.