The Regan and Llamas (2002) study included the three dimensions of naturalness identified by Tunnell: natural behavior, natural setting, and natural treatment. The natural behavior investigated was a store employee approaching a shopper. The setting was natural because the study took place in a mall; the natural treatment was type of dress. In reality, the treatment was imposed by a confederate, but it mirrored a behavior that could have occurred naturally. These are the types of behaviors Tunnell says we must strive for when we conduct field experimentation, as opposed to asking participants to provide self-reports or to recall their own behavior in some prior situation. Asking for such retrospective data only serves to introduce possible bias into the study