Most motivation theories in use today were developed in the United States by Americans and about Americans. Of those that were not, many have been strongly influenced by American theoretical work. Americans' strong emphasis on individualism has led to the expectancy and equity theories of motivation: theories that emphasize rational, individual thought as the primary basis of human behavior. The emphasis placed on achievement is not surprising given Americans' willingness to accept risk and their high concern for performance. The theories therefore do not offer universal explanations of motivation; rather, they reflect the values system of Americans.