“…Previous work has indicated that controllers evolved with NS function in a range of tasks of varying complexity (Velez and Clune, 2014) and such controllers consistently out-performed controllers evolved with objectivebased search in a range of ER tasks (Mouret and Doncieux, 2012;Gomes et al, 2015Gomes et al, , 2016. However, related research suggests that for complex tasks such as collective behavior tasks associated with swarm robotics (Duarte et al, 2016) (defined by high dimensional, rugged, discontinuous, and deceptive fitness landscapes (Eiben and Smith, 2003)), that evolutionary search hybridizing objectives (fitness functions) and NS tend to evolve effective high-quality solutions (behaviors) overall (Gomes and Christensen, 2013b;Gomes et al, 2013Gomes et al, , 2015. For a comprehensive survey of behavioral diversity maintenance methods used in various ER studies, the reader is referred to the review of Doncieux and Mouret (2014).…”