Positive illusions can have advantages and disadvantages for the individual, and there is a controversy over whether they are evolutionarily adaptive.[1] The illusions may have direct health benefits by helping the person cope with stress, or by promoting work towards success.[3] On the other hand, unrealistically positive expectations may prevent people from taking sensible preventive action for medical risks.[23] Research in 2001 provided evidence that people who have positive illusions may have both short term benefits and long term costs.