The aim of the research was to investigate the effects of information, feedback and commitment on car use and attitudes related to car use. In a field experiment (N = 350) users of private automobiles in The Netherlands monitored their travel behavior for four consecutive two-week periods. The participants received information and individual feedback about the effects of their car use on the environment and/or on their own finances. Information on public transport applicable to their situation was provided as well. Moreover, a subset of the participants committed themselves to reduce their mileage. Separate and combined effects of self-monitoring, environmental feedback, financial feedback, and commitment were analyzed. Effects on travel behaviour turned out to be absent. Effects on attitudes were in some cases opposite to what was expected from a theoretical point of view as well as what was considererd desirable from a policy point of view. The underlying psychological processes are discussed in terms of the social dilemma, dissonance reduction and reactance. Consequences for information campaigns are discussed.
