This dissertation explores the social and political implications of prejudice related to racial markers, or phenotypes, among members of what is usually considered a single racial group, Mestizo Mexicans and Mexican-Americans. By comparing these two groups, I analyze the effect of different contexts, in specific social norms, on people's behavior.

The study looks at whether subjects evaluate more positively and vote for a person/candidate with certain phenotypes (White) over another with different phenotypes (Indigenous). I also test if people evaluate more positively and vote for a person/candidate who looks phenotypically like them. The expectation is that phenotypes will affect Mexicans' behavior but not Mexican-Americans' because the former follow a social norm of racial inequality, while the latter embrace a social norm of racial equality.

I designed two experiments whose stimuli consist of pictures of phenotypically diverse individuals created using morphing software. There are three experimental conditions in each experiment: White, Mestizo, and Indigenous.

The first experiment tests the effect of phenotypic stereotypes on people's social judgments. It also looks at whether subjects differentiate among each other according to their phenotypes and explores subjects' knowledge of socially held stereotypes associated with different phenotypes. The subjects are undergraduate students from three different universities in Mexico City. Subjects showed knowledge of more negative traits attributed to Indigenous than to White or Mestizo phenotypes. The White individual was the best-evaluated followed, unexpectedly, by the Indigenous individual. Subjects liked the Mestizo person the least.

The second experiment looks at subjects' electoral behavior. I conducted this experiment in Mexico City and Chicago, recruiting people in public places. Mexican and Mexican-American subjects evaluated and expressed their vote intention for a proposed candidate. The results show that Mexican subjects evaluate more positively and prefer voting for a White candidate followed, unexpectedly, by the Indigenous candidate. Mexican-Americans do the opposite, by evaluating less positively and not tending to vote for the white candidate.

I argue that, to understand Mexicans' and Mexican-Americans' unexpected behavior, we have to understand the context in which they live and conclude by discussing the consequences of these findings for the study of race and politics.