1 Introduction Research report Age-related characteristics of risky decision-making and progressive expectation formation Zsófia Kardos a, b, ⁎ kardos.zsofia.klara@ttk.mta.hu Andrea Kóbor c Ádám Takács d Brigitta Tóth a, e Roland Boha a Bálint File a, f Márk Molnár a, d a Institute of Cognitive Neuroscience and Psychology, RCNS, HAS, Budapest, Hungary b Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary c Brain Imaging Centre, RCNS, HAS, Budapest, Hungary d Institute of Psychology, Eötvös Loránd University, Budapest, Hungary e Center for Computational Neuroscience and Neural Technology, Boston University, Boston, MA, USA f Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary ⁎ Corresponding author at: Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences ; , Magyar tudósok körútja 2 , H-1117 Budapest, Hungary. Abstract During daily encounters, it is inevitable that people take risks. Investigating the sequential processing of risk hazards involve expectation formation about outcome contingencies. The present study aimed to explore risk behavior and its neural correlates in sequences of decision making, particularly in old age, which represents a critical period regarding risk-taking propensity. The Balloon Analogue Risk Task was used in an electrophysiological setting with young and elderly age groups. During the task each additional pump on a virtual balloon increased the likelihood of a balloon burst but also increased the chance to collect more reward. Event-related potentials associated with rewarding feedback were analyzed based on the forthcoming decisions (whether to continue or to stop) in order to differentiate between states of expectation towards gain or loss. In the young, the reward positivity ERP component increased as a function of reward contingencies with the largest amplitude for rewarding feedback followed by the decision to stop. In the elderly, however, reward positivity did not reflect the effect of reward structure. Behavioral indices of risk-taking propensity suggest that the performance of the young and the elderly were dissociable only with respect to response times: The elderly was characterized by hesitation and more deliberative decision making throughout the experiment. These findings signify that sequential tracking of outcome contingencies has a key role in cost-efficient action planning and progressive expectation formation. Keywords: Aging; Decision making ; F eedback-related ERPs; Reward positivity; R isk-taking behavior