Influences of environment and personality on cognitive judgment bias in chickens

Cognitive processes include biases, such as cognitive judgment bias. Cognitive judgment bias influences how the surrounding is interpreted, and this can differ between individuals. However, thus far no formal framework exists to understand how cognitive judgment bias works. Here I investigated how environmental factors and personality influence cognitive judgment bias in Gallus gallus chicks. First I investigated how two environmental factors affected the cognitive judgment bias of laying hen chicks. Chicks were exposed to stress and/or environmental enrichment, and tested in a cognitive judgment bias test before and after collective unpredictable stressors were presented. The results showed that chicks living in enriched environments were faster to reach all cues after the collective stressors than chicks living in non-enriched environments. Individual differences are often observed in animals, even when raised under identical conditions; therefore I also investigated if variation in personality influence cognitive judgment bias. Red junglefowl chicks were thereby raised in equal environments and exposed to personality assays in addition to a cognitive judgment bias test. I demonstrated that less nervous chicks were more optimistic towards ambiguous and negative cues than more nervous chicks. Also previous studies have found indications of connections between cognitive bias and environment or personality. I conclude that environmental enrichment can buffer the influence of stress on cognitive judgment bias and that personality has a small influence on interpretations of stimuli. In the future, experiments in this field should focus on exploring more aspects on how cognitive biases occurs to improve our understanding of cognitive processes