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About us Campus Fryslân Centre for Sustainable Entrepreneurship

Dr. Berfu Ünal

Dr. A. Berfu Ünal is an Assistant Professor of Social Psychology at the Campus Fryslan of the RUG. Her research focuses on the social and cognitive processes behind decision-making and human behaviour. Notably, she explores how individual, social, and contextual factors interact to influence behaviour, performance, and thinking. She applies this expertise particularly to domains that remain to be important societal challenges in the face of sustainable development, such as facilitating pro-environmental behaviours (in particular recycling, waste-separation, car-use reduction and reduction of household energy use), adoption of sustainable innovations, and acceptability of environmental policies. In her research, she collaborates with experts from other disciplines and practitioners to develop unique approaches in triggering sustainable behaviours.


Geiger, J. L., Steg, L., van der Werff, E., & Ünal, A. B. (2019). A meta-analysis of factors related to recycling. Journal of environmental psychology, 64, 78-97.


The current meta-analysis aimed to identify the most important factors related to recycling across studies. A random-effects meta-analysis of studies on individual and household recycling (n = 91) revealed that both individual and contextual factors are related to recycling. Among individual factors, behaviour-specific factors (i.e., recycling self-identity, personal norms towards recycling, past recycling, and perceived behavioural control over recycling) were better predictors of recycling than general factors (i.e., general knowledge, general attitudes, general personal norm). Among contextual factors, the possession of a bin at home and house ownership were particularly predictive of recycling. Moreover, individual and contextual factors better predicted intention to recycle than self-reported recycling behaviour, and particularly than observed recycling behaviour. We discuss the theoretical and practical implications of our findings. We indicate that future studies could more systematically examine the effects of contextual factors on recycling, as well as the interplay of individual and contextual factors.

Last modified:10 March 2020 3.52 p.m.