Psychology deals with the behavior and experiences of individuals. It analyzes the processes that determine a person's emotional and cognitive world as well as their behavior. This thesis aims to demonstrate that psychological theories can explain processes in markets. Thus, it is positioned at the intersection of psychology and economics, where Behavioral Finance comes into play. This new research direction will be used to examine investor behavior. The application within the thesis involves transferring well-known psychological perspectives and theories to investor behavior. Consequently, the work contributes to explaining market events. It investigates the limitations that economic actions impose on the stock market. Furthermore, it aims to provide a deeper understanding of typical investor behavior.