Effects of anthropogenic change on animal cognition and emotion

Human activity is driving global biodiversity loss. However, the effects on animal cognition and emotion are less studied. In this thesis, I argue that anthropogenic change impacts animals’ mental states, with implications for both individuals (welfare) and populations (conservation). My first experiment explores the transition from keeping dairy cattle at pasture to housing them indoors full-time. Using a repeated-measures crossover design, I gave cows three weeks of overnight pasture access and three weeks of indoor housing. Treatment did not influence judgements of ambiguous stimuli – a cognitive measure of emotional wellbeing. Nevertheless, behavioural welfare indicators (lying, walking, and anticipatory behaviour) suggested that subjects had more comfortable, rewarding lives at pasture. Next, I review attention bias, another potential cognitive indicator of animal wellbeing. Attention to threat proves a promising method to quantify the emotional impacts of anthropogenic stressors. I then investigate a second example of human-induced environmental change: oceanic microplastic pollution. Microplastic exposure prevented hermit crabs from approaching and entering a new shell, which was better than their current shell. These results suggest that microplastics disrupt animal cognition (resource assessment and evaluation). Finally, I apply emotion theory to animal contests, and argue that emotions underpin virtually all non-reflexive behaviour. Because emotions generalise across contexts, my novel approach suggests that human activity has broader psychological impacts than usually recognised. These findings highlight how anthropogenic change can influence animal cognition and emotion, with practical applications for welfare and conservation.