Definitions and methods for assessing the mental states of animals

Abstract

Initially restricted to the absence of negative emotion and respect for the needs of animals, animal welfare is defined as resulting from a positive mental state. This paradigm shift has placed mental states at the centre of animal welfare research. However, it is still difficult to understand and assess them, two objectives that we aim to achieve in this article. After mentioning a few historical and scientific elements that we consider fundamental, we propose defining mental states as all the processes involved in affective states, social cognition, physical cognition, and embodied cognition. This definition is consistent with the definition and methods used to assess animal welfare, which initially focused on affective states such as emotions. We will review several experimental approaches to understanding the affective states of farm animals and some approaches used to assess them in livestock farming. To access other mental states such as the different forms of cognition, we propose to explore the approaches used to diagnose and manage the mental health of animals and humans. In particular, we are interested in the Research Domain of Criteria (RDoC) project, which provides a relevant framework for investigating and assessing the mental states of animals. We will discuss its benefits and look ahead to the implementation of such a project to explore the biological substrates of mental states, identify new indicators of welfare, and initiate an approach integrating both welfare and health.