Modernization theory, developed in the 1950s and 1960s, is a field of sociology that examined the economic evolution of societies (see the source below). According to this theory, in low-income countries, people are focused on daily needs and survival. Their values focus on survival and safety, as these are the most important and most attainable goals. In higher-income countries, most people have met their goals of economic and physical safety (though there are still people who struggle with these goals). Therefore, people at higher economic levels within these countries are able to focus on different goals, such as those that foster individuality and capitalism. In the United States, for example, many, but not all, people have the ability to pursue studies that build on their interests and values and that allow them to express their values. They focus on expressing themselves through their work, choice of living situation, and family. Their values are focused on personal choice and fulfillment.
Eisenstadt, S. N. 1966 Modernization: Protest and Change. Englewood Cliffs, N.J.: Prentice-Hall.