“…Parallel to the increasing popularity of gamification in crowdsourcing, academic research on the topic has steadily increased and can be expected to continue increasing in the future (Morschheuser et al, 2017). To date, studies examining gamification mainly focused on three aspects: (1) the effectiveness of individual gamification affordance, such as points and leaderboard (Prestopnik & Tang, 2015;Talasila, Curtmola, & Borcea, 2016), storytelling and avatar (Prandi, Nisi, Salomoni, & Nunes, 2015;Sakamoto & Nakajima, 2014), and competitive or cooperative gaming design (Morschheuser et al, 2017; Pe-Than, Goh, & Lee, 2017); (2) the efficiency of gamified crowdsourcing tasks in terms of participation (Eickhoff, Harris, de Vries, & Srinivasan, 2012;Kawajiri, Shimosaka, & Kahima, 2014), output engagement (Goncalves, Hosio, Ferreira, &Kostakos, 2014), andpsychological outcomes (e.g., enjoyment, Altmeyer, Lessel, &Krüger, 2016); and (3) the motivations of using gamified crowdsourcing, such as social influence (Hamari & Koivisto, 2015), intrinsic motivations (Mekler, Brühlmann, Tuch, & Opwis, 2017), and esthetic experience (Wang, Goh, Lim, & Vu, 2016;Wang et al, 2017). Such results provide empirical evidence for gamification developments, providing designers with guidelines in ways of encouraging and engaging users in the crowdsourcing tasks.…”