Simple Summary Optimism and pessimism may affect the way individuals perceive elements of the environment which they are surrounded by, but the mechanisms behind these processes are yet to be thoroughly described. The present study addresses judgement bias and its correlation with personality in Miniature Donkeys. Individuals were scored on eighteen personality traits and their response to an ambiguous stimulus. Judgement bias presents intrinsic individual differences. The correlation found between patience and pessimism suggests that personality-related conditions may shape the way individuals interpret new stimuli. Improving our knowledge of tools that measure donkeys mood may play a pivotal role from an animal welfare perspective, as it may provide a better understanding of individuals interaction among handlers, congeners, and with the environment, and issue their own verdicts after such interactions. Expectation-related bias may configure individuals perception of their surrounding environment and of the elements present in it. This study aimed to determine the repercussions of environmental (weather elements) or subject-inherent factors (sex, age, or personality features) on judgment bias. A cognitive bias test was performed in eight Miniature jennies and four jacks. Test comprised habituation, training and testing phases during which subjects were trained on how to complete the test and scored based on their latency to approach an ambiguous stimulus. A questionnaire evaluating eleven personality features was parallelly completed by three caretakers, five operators and two care assistants to determine the links between personality features and judgment bias. Adjusted latencies did not significantly differ between sexes (Mann-Whitney test, p > 0.05). Although Miniature donkeys can discriminate positive/negative stimuli, inter-individual variability evidences were found. Such discrimination is evidenced by significant latency differences to approach positive/negative stimuli (33.7 +/- 43.1 vs. 145.5 +/- 53.1 s) (Mann-Whitney test, p < 0.05). Latencies significantly increased with patience, indicative of an expression of pessimism. Better understanding judgement bias mechanisms and implications may help optimize routine handling practices in the framework of animal welfare.