We can describe cognition as the mental processes involved when processing signals and information from our surroundings. Despite being vital for our actions, these processes can be biased by emotions, which results in a judgement bias of ambiguous information. Depressed individuals tend to be pessimistic about such ambiguous information, while individuals under normal or good condition, tend to be optimistic. This is true also for animals. Based on this, cognitive judgement bias tests are developed to measure the affective state of individuals. However, cognitive judgement bias tests require extensive pre-test training for animals to learn positive and negative reference cues. An alternative to using responses to pre-learnt cues could be to use naturally aversive stimuli instead. Eyespot patterns on lepidopterans can be aversive to birds. However, it is scarcely investigated if eyespot patterns can be used to measure affective state. The aim of my study was therefore to investigate if eyespots patterns can replace classic cues in cognitive judgment bias tests measuring affective state. I did so by comparing behavioural responses of red junglefowl chicks (Gallus gallus) to both eyespot patterns and classical cues in a cognitive judgement bias test. Responses correlated between some cues in the two tests, suggesting that eyespot patterns may work as a replacement of pre-learnt cues. However, no differences in responses to the eyespot patterns was found, and so further work is needed to improve the design of eyespot cues to obtain a clearer correlation between responses to eyespot patterns and classical pre-learnt cues in cognitive judgement bias tests. As less training is needed, such improved tests could have positive implications, and be a simpler and more user-friendly way to measure affective state in animals.

The Red Junglefowl is a species of bird that was domesticated by humans around 8 000 years ago. Over time, domestication has led to changes in behavior and morphology, made possible by reduced fear of humans. Fear has been shown to affect cognitive processes, such as the way ambiguous stimuli are perceived by the individual. In this study, I observed the behavior of Red Junglefowl hens that had been selected for either high or low fear of humans to see how the early stages of domestication would affect their tendency to make pessimistic or optimistic judgements. The hens were put in a test arena where they were exposed to positive, negative, and ambiguous stimulus cues, and the time taken to approach each was measured. Hens that had been selected for low fear of humans had overall, albeit not significantly, shorter latencies to approach ambiguous cues. In other words, they were more likely to make optimistic judgements. The results were also affected by the order each stimulus cue was presented. I conclude that domestication may influence the way Red Junglefowl perceive ambiguous stimuli by reducing pessimism.

Affective states of animals are emotions with positive or negative valance. Positive and negative affective states affect animal welfare, and can bias interpretation of information positively or negatively, respectively. Judgement bias tests measure affective states based on responses to ambiguous cues, intermediate to cues with learnt positive and negative outcomes. Responses closer to those of positive cues indicate positive affective state. However, animals need extensive training to learn initial associations to reference cues. Therefore, I here aimed to validate an alternative affective state test based on instinctive avoidance of patterns resembling eyespots. Responses to ambiguous eyespot cues similar to responses to full eyespot cues could indicate negative affective state. To test this, behavioural responses of red junglefowl (Gallus gallus) chicks to ambiguous cues from a validated judgement bias test were compared to responses to cues resembling eyespots. In a second cohort of birds, I developed simplified tests with only one ambiguous cue in each tests. I predicted that responses in both tests would correlate positively. In the original tests, shorter distance and latency to approach ambiguous cues correlated positively with latency to approach one of the eyespot cues, a full eyespot cue. This pattern was only observed in females. In the simplified tests, at 4 weeks of age, shortest latency to approach cues correlated among tests. This pattern was not observed when chicks were tested at 2 weeks of age. Overall, the eyespot test is a promising alternative affective state test, but further studies exploring sex- and age-effects, are needed.