Identifying bias in self-reported pro-environmental behavior

Research on pro-environmental behavior (PEB) informs social policies and interventions, so the quality of PEB measurement is critical. Self-reported PEB measures in surveys often contain non-negligible measurement error that can bias estimates and lead to incorrect findings. Given the potential presence of error, we hypothesize that changes to the way self-reported PEB is measured might lead to systematic measurement errors that affect the validity of results. Study 1 (N = 951) showed that priming participants with related scales like environmentalist identity did not substantively change reported behavior (all ds ≤ 0.12). To investigate the possibility of overreporting without priming, Study 2 (N = 385) measured littering prevention behavior using the Unmatched Count Technique. A standard questionnaire format led to much higher reported behavior compared to the more anonymous covert condition, d = 0.53, and this effect appeared driven by participants who reported a stronger environmentalist identity. These results may help to explain some of the observed error in PEB measures. We suggest that researchers could reduce measurement bias with indirect questioning techniques.