A study by Richard Bagozzi, Nancy Wong and Youjae Yi, examines the interaction between culture and gender that produces distinct patterns of association between positive and negative emotions. The United States was considered a more 'independence-based culture', while China was considered 'interdependence-based'. In the US people tend to experience emotions in terms of opposition whereas in China, they do so in dialectical terms (i.e., those of logical argumentation and contradictory forces). The study continued with sets of psychological tests among university students in Beijing and in Michigan. The fundamental goals of the research were to show that "gender differences in emotions are adaptive for the differing roles that males and females play in the culture". The evidence for differences in gender role was found during the socialization in work experiment, proving that "women are socialized to be more expressive of their feelings and to show this to a greater extent in facial expressions and gestures, as well as by verbal means". The study extended to the biological characteristics of both gender groups — for a higher association between PA and NA hormones in memory for women, the cultural patterns became more evident for women than for men.