The main sources of decision bias in people are loss aversion and subjective weighting of probability. Experiments show that people willing accept losses for the sake of common good like altruistically punishing free riders in public goods games. Giving donation to charities is a clear demonstration of altruism overcoming loss aversion. Also, people are more objective in evaluating probabilities while making decisions for others. The common theme of social norms displays the potential to effectively address both the sources of decision bias separately. Our research examines whether social norms can be primed to directly reduce decision biases compared to making decisions under market norms. Experiments show that the level of effort exerted by people varies directly in proportion to the magnitude of the reward offered when the reward is monetary in nature and a transactional contract is created. It is consistent irrespective of the magnitude of the reward offered when rewards are non-monetary in nature and resembles gifts, evoking relationship-based contract. The common thread of commitment and consistency observed under social norms could be leveraged to reduce decision bias since the core of irrationality or bias is inconsistency in preferences. Our research uses probabilistic lotteries which resemble real life financial decisions and hence attempts to reduce bias in individual financial decisions.