Preferences With and Without Prices - does the price attribute affect behavior in stated preference surveys?

The experimental as well as the nonmarket valuation literature include several examples of how an introduced price can affect behavior in otherwise not expected ways. It has become standard to include a price vector as an attribute in choice experiments, something that enables us to estimate a marginal willingness to pay for other attributes. We test the impact on preferences by an inclusion of a price in a choice experiment. Preferences are affected, as might be expected. However, also the relative ranking of individual attributes is affected. We end on a positive note, observing that a price seems to drive out zero price opinions, e.g. warm glow values