Marwa El Zein is a Wellcome Trust research fellow at the Institute of Cognitive Neuroscience (University College London) and at the Adaptive Rationality Center (Max-Planck for Human Development). Her research investigates how and why humans engage in collective decisions and aims to characterize the cognitive and neural mechanisms underlying collective decisions. Her PhD work at the Laboratoire de Neurosciences Cognitives (Ecole Normale Superieure) investigated how perceptual decisions about facial expressions of emotion are shaped by contextual social information. Her research aim is to reach a good understanding of social behaviours and their underlying neural mechanisms from the very perception of social others to complex group decision-making to important societal domains. She is particularly interested in applying her work to political decision-making and evidence-based policy change, as well as medical decision-making and mental health/well-being issues.