App-etizing sustainability: A multi-component app intervention targeting dietary carbon emissions informed by personal needs

Reduction of animal product consumption yields great benefits for both environmental sustainability and human health. Yet, the efficacy of online interventions remains largely untested. Also, despite promising evidence of personality science, design and testing of such interventions rarely accounts for a responsiveness effect due to interindividual differences. To fill this gap, we developed a multi-component app intervention informed by barriers and benefits of meat reduction, including personality. In a 30-day RCT on N=113 students, our intervention joins a multitude of effective strategies and was tested against a dietary protocol app as control. Results of multilevel modelling showed an average reduction of 12 grams dietary CO₂e per day across conditions. Moreover, higher psychopathy predicted a higher rate of change, however likely due to regression to the mean. Contrarily, we explain lower responsiveness of elevated psychopathy in the control by an incongruence between psychopaths' anti-social tendency and the target behavior. Self-selection bias in our sample and future directions are discussed.