This book constitutes the refereed proceedings of the 12th International Conference on Engineering Psychology and Cognitive Ergonomics, EPCE 2015, held as part of the 17th International Conference on Human-Computer Interaction, HCII 2015, held in Los Angeles, CA, USA, in August 2015. The total of 1462 papers and 246 poster papers presented at the HCII 2015 conferences was carefully reviewed …