Erikson's stage theory characterizes an individual advancing through the eight life stages as a function of negotiating their biological and sociocultural forces. The two conflicting forces each have a psychosocial crisis which characterizes the eight stages. If an individual does indeed successfully reconcile these forces (favoring the first mentioned attribute in the crisis), they emerge from the stage with the corresponding virtue. For example, if an infant enters into the toddler stage (autonomy vs. shame and doubt) with more trust than mistrust, they carry the virtue of hope into the remaining life stages. The challenges of stages not successfully completed may be expected to return as problems in the future. However, mastery of a stage is not required to advance to the next stage. In one study, subjects showed significant development as a result of organized activities.