Social dominance orientation
Social dominance orientation (SDO) is a personality trait which predicts social and political attitudes, and is a widely used social psychological scale. SDO is conceptualised as a measure of individual differences in levels of group-based discrimination; that is, it is a measure of an individual's preference for hierarchy within any social system and the domination of inferior groups. It is a predisposition toward anti-egalitarianism within and between groups. The concept of SDO as a measurable individual difference is a product of Social Dominance Theory.
Individuals who score high in SDO desire to maintain and, in many cases, increase the differences between social statuses of different groups, as well as individual group members. Typically, they are dominant, driven, tough, and relatively uncaring seekers of power. People high in SDO also prefer hierarchical group orientations. Often, people who score high in SDO adhere strongly to belief in a "dog-eat-dog" world. It has also been found that men are higher than women in SDO measures 
Social dominance theory 
SDO was first proposed by Jim Sidanius and Felicia Pratto as part of their Social Dominance Theory (SDT). SDO is the key measurable component of SDT that is specific to it.
SDT begins with the empirical observation that surplus-producing social systems have a threefold group-based hierarchy structure: age-based, gender-based and “arbitrary set-based,” which can include race, class, sexual orientation, caste, ethnicity, religious affiliation, etc. Age-based hierarchies invariably give more power to adults and middle-age people than children and younger adults, and gender-based hierarchies invariably grant more power to one gender over others, but arbitrary-set hierarchies—though quite resilient—are truly arbitrary.
SDT is based on three primary assumptions:
1. While age- and gender-based hierarchies will tend to exist within all social systems, arbitrary-set systems of social hierarchy will invariably emerge within social systems producing sustainable economic surpluses.
2. Most forms of group conflict and oppression (e.g., racism, homophobia, ethnocentrisim, sexism, nationalism, classism, regionalism) can be regarded as different manifestations of the same basic human predisposition to form group-based hierarchies.
3. Human social systems are subject to the counterbalancing influences of hierarchy-enhancing (HE) forces, producing and maintaining ever higher levels of group-based social inequality, and hierarchy-attenuating (HA) forces, producing greater levels of group-based social equality.
SDO is the individual attitudinal aspect of SDT. It is influenced by group status, gender (women score lower on SDO), socialization, and temperament. In turn, it influences support for HE and HA "legitimating myths," defined as “values, attitudes, beliefs, causal attributions and ideologies” that in turn justify social institutions and practices that either enhance or attenuate group hierarchy.
Early development of SDO 
While the correlation of gender with SDO scores has been empirically measured and confirmed, the impact of temperament and socialization is less clear. Duckitt has suggested a model of attitude development for SDO, suggesting that unaffectionate socialisation in childhood causes a tough-minded attitude. According to Duckitt's model, people high in tough-minded personality are predisposed to view the world as a competitive place in which resource competition is zero-sum. A desire to compete, which fits with social dominance orientation, influences in-group and outside-group attitudes. People high in SDO also believe that hierarchies are present in all aspects of society and are more likely to agree with statements such as "It's probably a good thing that certain groups are at the top and other groups are at the bottom". In turn, SDO predicts stereotyping, discrimination and prejudice.
SDO Scale 
SDO has been measured by a series of scales that have been refined over time, all of which contain a balance of pro- and contra-trait statements or phrases. A 7-point Likert scale is used for each item; participants rate their agreement or disagreement with the statements from 1 (strongly disagree) to 7 (strongly agree). Most of the research was conducted with the SDO-5 (a 14-point scale) and SDO-6.
- Some groups of people are simply inferior to other groups.
- In getting what you want, it is sometimes necessary to use force against other groups.
- It’s OK if some groups have more of a chance in life than others.
- To get ahead in life, it is sometimes necessary to step on other groups.
- If certain groups stayed in their place, we would have fewer problems.
- It’s probably a good thing that certain groups are at the top and other groups are at the bottom.
- Inferior groups should stay in their place.
- Sometimes other groups must be kept in their place.
- It would be good if groups could be equal.
- Group equality should be our ideal.
- All groups should be given an equal chance in life.
- We should do what we can to equalize conditions for different groups.
- Increased social equality is beneficial to society.
- We would have fewer problems if we treated people more equally.
- We should strive to make incomes as equal as possible.
- No group should dominate in society.
Keying is reversed on questions 9 through 16, to control for acquiescence.
Criticisms of the Social Dominance Orientation Construct 
Rubin and Hewstone (2004) argue that social dominance theory has changed its focus dramatically over the years, and these changes have been reflected in different versions of the social dominance orientation construct. Social dominance orientation was originally defined as “the degree to which individuals desire social dominance and superiority for themselves and their primordial groups over other groups” (p. 209). It then quickly changed to not only “(a) a…desire for and value given to in-group dominance over out-groups” but also “(b) the desire for nonegalitarian, hierarchical relationships between groups within the social system” (p. 1007). The most recent measure of social dominance orientation (see SDO-6 above) focuses on the “general desire for unequal relations among social groups, regardless of whether this means ingroup domination or ingroup subordination” (p. 312) Given these changes, Rubin and Hewstone believe that evidence for social dominance theory should be considered “as supporting three separate SDO hypotheses, rather than one single theory” (p. 22). 
Group-based and individual dominance 
Robert Altemeyer said that people with a high SDO want more power (agreeing with items such as "Winning is more important than how you play the game") and more Machiavellian (manipulative and amoral) agreeing with items such as "There really is no such thing as 'right and wrong'. It all boils down to what you can get away with."
These observations are at odds with conceptualisations of SDO as a group-based phenomenon, suggesting that the SDO reflects interpersonal dominance, not only group-based dominance. This is supported by Sidanius and Pratto's own evidence that high-SDO individuals tend to gravitate toward hierarchy-enhancing jobs and institutions, such as law enforcement, that are themselves hierarchically structured vis-a-vis individuals within them.
SDO correlates weakly with right-wing authoritarianism (RWA) (r ≈ .18). Both predict attitudes, such as sexist, racist, and heterosexist attitudes. The two contribute to different forms of prejudice; SDO correlates to higher prejudice against "derogated" groups, RWA correlates to higher prejudice against "dangerous" groups, while both are associated with increases in prejudice for "dissident" groups. SDO and RWA contribute to prejudice in an additive rather than interactive way (the interaction[clarification needed] of SDO and RWA accounted, in one study, for an average of less than .001% variance in addition to their linear combination), that is the association between SDO and prejudice is similar regardless of a person's level of RWA, and vice versa. However, little research has been done relating directly to behavior.
Correlation with conservative political views 
Felicia Pratto and her colleagues have found evidence that a high Social Dominance Orientation is strongly correlated with conservative political views, and opposition to programs and policies that aim to promote equality (such as affirmative action, laws advocating equal rights for homosexuals, women in combat, etc.).
There has been some debate within the psychology community on what the relation is between SDO and racism/sexism. One explanation suggests that opposition to programs that promote equality need not be based on racism or sexism but on a "principled conservatism", that is, a "concern for equity, color-blindness, and genuine conservative values".
Some principled-conservatism theorists have suggested that racism and conservatism are independent, and only very weakly correlated among the highly educated, who truly understand the concepts of conservative values and attitudes. In an effort to examine the relationship between education, SDO, and racism, Sidanius and his colleagues asked approximately 4,600 Euro-Americans to complete a survey in which they were asked about their political and social attitudes, and their social dominance orientation was assessed. Results partially supported the principled-conservatism position, but also suggest several problems. Contrary to what these theorists would predict, correlations among SDO, political conservatism, and racism were strongest among the most educated, and weakest among the least educated. Sidanius and his colleagues hypothesized this was because the most educated conservatives tend to be more invested in the hierarchical structure of society and in maintaining the inequality of the status quo in society in order to safeguard their status.
Sex differences in SDO 
Males are observed to be more socially hierarchical, as indicated by speaking time, and yielding to interruptions. The proposed biological reason for this difference in dominance is increased levels of androgens.
SDO is typically measured as an individual personality construct. However, cultural forms of SDO have been discovered on the macro level of society  Discrimination, prejudice and stereotyping can occur at various levels of institutions in society, such as transnational corporations, government agencies, schools and criminal justice systems. The basis of this theory of societal level SDO is rooted in evolutionary psychology, which states that humans have an evolved predisposition to express social dominance that is heightened under certain social conditions (such as group status) and is also mediated by factors such as individual personality and temperament. Democratic societies are lower in SDO measures  The more that a society encourages citizens to cooperate with others and feel concern for the welfare of others, the lower the SDO in that culture. High levels of national income and empowerment of women are also associated with low national SDO, whereas more traditional societies with lower income, male domination and more closed institutional systems are associated with a higher SDO. Individuals who are socialized within these traditional societies are more likely to internalize gender hierarchies and are less likely to challenge them. In terms of Social Dominance Theory, it can be interpreted that in evolutionary terms, humans have evolved preferences for group-based hierarchies.
The biology of SDO is unknown. Noting that males tend to have higher SDO scores than females, Sidanius and Pratto speculate that SDO may be influenced by hormones that differ between the sexes, namely androgens, primarily testosterone. Male levels of testosterone are much higher than that of females.
See also 
- Sidanius, Jim; Pratto, Felicia (2001). Social Dominance: An Intergroup Theory of Social Hierarchy and Oppression. Cambridge: Cambridge University Press. ISBN 0-521-80540-6.
- Levin, S.; Federico, C. M., Sidanius, J., & Rabinowitz, J. L. (2002). "Social dominance orientation and intergroup bias: The legitimation of favoritism for high-status groups". Personality and Social Psychology Bulletin 28 (2): 144–157. doi:10.1177/0146167202282002.
- Forsyth, D.R. (2009). Groun Dynamics: New York: Wadsworth [Chapter 7]
- Pratto, F.; Stallworth, L. M., & Sidanius, J. (1997). "The gender gap: Differences in political dominance and social dominance orientation". British Journal of Social Psychology 36 (1): 49–68. doi:10.1111/j.2044-8309.1997.tb01118.x.
- Rubin, M., & Hewstone, M. (2004). Social identity, system justification, and social dominance: Commentary on Reicher, Jost et al., and Sidanius et al. Political Psychology, 25, 823-844. doi: 10.1111/j.1467-9221.2004.00400.x
- Sidanius, J. (1993). The psychology of group conflict and the dynamics of oppression: A social dominance perspective. In S. Iyengar & W. J. McGuire (Eds.), Explorations in political psychology (pp. 183 219). Durham, NC: Duke University Press.
- Sidanius, J., Pratto, F., & Bobo, L. (1994). Social dominance orientation and the political psychology of gender: A case of invariance? Journal of Personality and Social Psychology, 67, 998 1011.
- Sibley, Chris G.; Robertson, Andrew; Wilson, Marc S. (2006). "Social Dominance Orientation and Right-Wing Authoritarianism: Additive and Interactive Effects". Political Psychology 27 (5): 755. doi:10.1111/j.1467-9221.2006.00531.x.
- Duckitt, John; Sibley, Chris G. (March 2007). "Right wing authoritarianism, social dominance orientation and the dimensions of generalized prejudice". European Journal of Personality 21 (2): 113–130. doi:10.1002/per.614.
- Duckitt, John; Sibley, Chris G. (June 2010). "Right-wing authoritarianism and social dominance orientation and the dimensions of generalized prejudice: A longitudinal test". European Journal of Personality 24 (4): 324–340. doi:10.1002/per.746.
- Pratto, Felicia; Sidanius, Jim; Stallworth, Lisa M.; Malle, Bertram F. (1994). "Social dominance orientation: A personality variable predicting social and political attitudes". Journal of Personality and Social Psychology 67 (4): 741–763. doi:10.1037/0022-35220.127.116.111.
- Sidanius, J; Pratto, F; Bobo, L (1996). "Racism, conservatism, affirmative action, and intellectual sophistication: A matter of principled conservatism or group dominance?" (PDF). Journal of Personality and Social Psychology 70 (3): 476–490. doi:10.1037/0022-3518.104.22.1686.
- Schmid Mast, M. (2002). "Dominance as epressed and inferred through speaking time: A meta-analysis". Human Communication Research 28: 420–450.
- Schmid Mast, M. (2002). "Female dominance hierarchies: Are they any different from males?". Journal of Personality and Social Psychology 28: 29–39. doi:10.1177/0146167202281003.
- Fischer,Hanke & Sibley.(2012).Cultural and Institutional Determinants of Social Dominance Orientation: A Cross-Cultural Meta-Analysis of 27 Societies