Final Report Summary - OPTIMAL TIMING (Interval Timing, Decision Making, and Reward Maximization) In this project (EU-FP7 IRG 277015, Optimal Timing), the fellow investigated temporal and non-temporal decision making within the framework of optimality. The planned studies aimed to advance the study of temporal risk assessment in tasks that involved different decisions and imposed different constraints on the problem of reward maximization. Several of these studies showed that in many experimental scenarios that required participants to withhold responding for a fixed minimum amount of time (learning to wait) or to retrospectively discriminate experienced time intervals based on their similarity to two reference durations, human participants can accurately represent the level of their endogenous timing uncertainty, exogenous probabilities, and incorporate this information into their decisions in a nearly normative fashion. However, another set of studies showed that the optimal temporal risk assessment performance does not generalize to decision scenarios with more than two options. For instance, in scenarios which required the participants to make two subsequent prospective decisions, participants were nearly optimal in their initial time-based choices but diverged from optimality in their subsequent decisions. Another experiment tested the perceptual decision-making performance under time pressure. The findings of this study showed that humans could not approximate the optimal decision-strategies under response deadlines. In other words, they could not modulate their decision thresholds dynamically within a trial even when this was required for reward rate maximization. The fellow has further extended the scope of these studies to include clinical populations, animal research, behavioral genetics, and brain stimulation methods. The fellow has also conducted extensive modeling work and characterized the processing dynamics that underlie interval timing and retrospective temporal decision-making within an overarching decision-theoretic framework. The neural models that effectively implement similar processes and make decisions about time intervals were also developed. Many of these studies have been published or are under review in peer-reviewed international journals. One completed study is currently being prepared to be submitted for publication.This grant has extensively benefited the career development and the long-term re-integration of the fellow. He has co-established a human behavioral laboratory and transcranial magnetic stimulation laboratory, and established an animal behavioral research laboratory. He is currently the director/co-director of these research facilities. The fellow has received the title of associate professorship along with a number of prestigious awards during this project. For instance, he received TÜBİTAK Incentive Award 2014, which is the most prestigious award given to scientists below 40 in the host country, he was honored as the Young Scientist by the World Economic Forum (2013), as well as the The Science Academy (2013). He also received the Outstanding Faculty Award (2013-2014) from the host institution. The fellow has recently been nominated for the Turkish Academy of Sciences-Young Scientist Award by the host institution (evaluation in progress). During this project, the fellow received an international and three national research grants, and an institutional teaching grant. Briefly, this grant highly benefited the scientific and career development of the fellow and facilitated the achievement of his career goals and his long-term integration into the host institution.