“…The judgement bias task has become increasingly important for the study of animal welfare, and has been applied to various species (see Lagisz et al, 2020 for a review), predominantly in captive settings (Bethell, 2015): Farm livestock (Baciadonna & McElligott, 2015), horses (Henry et al, 2017), non-human primates (Bateson & Nettle, 2015;Bethell et al, 2012), dolphins (Clegg et al, 2017), dogs (Burman et al, 2011;Mendl, Brooks, et al, 2010), rodents (Bethell & Koyama, 2015;Nguyen et al, 2020), songbirds (Bateson & Matheson, 2007;Brilot et al, 2009;Matheson et al, 2008;McCoy et al, 2019), fish (Tan, 2017) and also, although very rarely, insects. Honeybees (Apis mellifera carnica) and fruit flies (Drosophila melanogaster) were found to more likely classify ambiguous cues as predictive of a negative outcome after they encountered an artificial predator attack, simulated by vigorous shaking (Bateson et al, 2011;Deakin et al, 2018;Schlüns et al, 2017). Bumblebees (Bombus terrestris) that received an unexpected reward (droplet of sucrose solution) expressed optimism in a judgment bias task and subsequently also recovered faster from a experimentally induced predator attack (Solvi et al, 2016).…”