Simon's research interests are in the area of behavioural and experimental economics, organisational economics, labour economics, and game theory. His main research tools are experiments. Currently, his main research interests are on voluntary cooperation in the presence of free rider incentives, and on the interplay of material and psychological incentives in incentive provision. He has published in American Economic Review, Econometrica, Science, Nature, Journal of Economic Perspectives, Journal of Labor Economics, Journal of Public Economics, Journal of the European Economic Association, Management Science, Nature Human Behaviour and Nature Communications. He held a £1.5m European Research Council (ERC) Advanced Investigator grant on the Behavioural Economics of Cooperation (2012-2017). He was recently awarded another ERC Advanced Grant on the Behavioural Principles of Large-Scale Cooperation (2021 - 2026).