Financial decisions are difficult. They involve a lot of uncertainties. Whether the future market development, the future income or the future need for financial resources. When people are confronted with such difficult decisions, they do not always act according to the rules of rational decision-making, as classical models of Standard Finance (based on the "Homo Oeconomicus"), such as the Expected Utility Theory, claim. They are influenced by psychological effects and seek ways to simplify these decisions. For this they use so-called heuristics or mental abbreviations. These heuristics do serve a purpose, since they lead to acceptable results with relatively little mental effort in most cases. In some cases, however, these heuristics lead to systematic behavior patterns, which can not be explained by the classical models of decision theory. These behavioral patterns are attributed to so-called Behavioral Finance (based on the "Homo Sapiens").This thesis presents, after a comparison between Standard Finance and Behavioral Finance, two of the most frequently observed phenomena of Behavioral Finance (the behavior according to Prospect Theory and the "Overconfidence") and describes how they can express themselves in decision-making situations and what effects these have on the financial market. The last section, which is the main part of this thesis, deals with the question whether the described phenomena can be proven in real decision-making situations, and what effects the demographic characteristics gender, age and level of education have on the results. To this end, the results of the survey carried out for this purpose are evaluated, summarized and analyzed, and a comparison is made with the existing results of the literature.