Abstract
Within social psychology and sociology there is a field of study in charge of studying how the social group affects the individual in all areas. In fact, several studies have found that the social decision-making process can be influenced by cognitive biases. This fields establishes two large categories of social groups called ingroup and outgroup depending on whether individuals are part of this group or not. Therefore, an ingroup is a social group to which a person psychologically identifies as being a member. By contrast, an outgroup is a social group with which an individual does not identify. Moreover, the psychological membership of social groups and categories can be related with different aspects such as race, profession, religion, among others, so that individuals can categorize themselves and others in different ways, usually dependent on the context. This categorization that individuals do based in the pertinence to a group and the influence of the group on the person reproduce in the person social cognitive biases that can lead to erroneous decisions. Within these biases the best known is the ingroup bias. This chapter explores some of these social biases and how they influence the decision-making process.