Thesis (Ph. D.)--University of Chicago. / Reprinted from the Journal of Comparative Neurology and Psychology, Vol. 19, No. 1, 1909. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago. / Reprinted from the Journal of Comparative Neurology and Psychology, Vol. 19, No. 1, 1909. Includes bibliographical references. Also available on the Internet. Also issued online.

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Jeffrey B. Rosen, Dept. of Psychology. Includes bibliographical references.

Animal welfare has long been a subject under debate. Since animals are unable to voice concerns about their living standards it is of interest to find other ways to secure their wellbeing. A new measurement has been introduced where animals’ own judgement can act as an indicator for their emotional state and welfare. This study summarizes key elements from previous literature and research in order to explain the connection between welfare and judgement bias. Emotions have been defined as either an observable reaction to a stimulus or a subjective conscious experience of the stimulus. The second has been difficult to assess in animals since they cannot vocalise their own interpretations, hence emotions in animals are assessed based on the first definition. The study of animal welfare is in short the study of animal’s judgement of the world, which in turn indicate how animals feel. Cognitive judgement bias has been defined as whether an animal assess an ambiguous stimulus as negative or positive, a common method used to demonstrate this concept is the go no-go method. Animals learn to discriminate between two stimuli and is then presented with an ambiguous stimulus. The response to the ambiguous stimulus is recorded and determine if the animal is optimistic or pessimistic in its judgement. Research has been rather successful in determining factors which can affect animal welfare, opening up for deeper discussions concerning animal cognition, awareness and their effect on welfare, but further refinements are required to assess the influence of judgement bias.