The analysis of bank customer behavior has been considered of great interest by international banking in the past few years and has gained greater relevance during the economic and social crisis that started between 2007 and 2008. Portuguese bank customers behavior is analyzed by the comparison of data obtained prior to the economic crisis in 2007 with data obtained a few years after in 2013, using survey results with statistical relevance. In this study was also used data and information from recognized entities, including customer satisfaction and trust information from ECSI Portugal. Globalization, seen as a simultaneous transformation in the economy, politics and culture, resulted in a more intense competition and companies deepen methods to improve customer acquisition and loyalty. Scientific development, particularly in the field of behavioural economics, which includes many contributions of Psychology and Sociology, as well as in the field of Neurology that gave rise to Neuroeconomics, has allowed the adaptation and change of traditional economic theories of decision making, based only on economic rationality, in the wake of the Cartesian dualism and Newtonian atomism, allowing for a better understanding of the decision making on the part of the individuals. It is demonstrated that the element currently more relevant to customer satisfaction and loyalty towards their main bank in Portugal is trust. We also conclude that Portuguese customers trust in banks evolution over the last few years is not as negative as we could expect, considering all the problems that have been affecting this sector, but something new is happening because today customers satisfaction is decreasing. There is a significant shift in the banking activity, with a rather different approach from what we had traditionally known. This means that banking activity is changing, and this new way may lead to a further decline in customer trust.