Do animals live in the present?: Current evidence and implications for welfare

Abstract

The importance of understanding the mental experiences of animals in order to assess their welfare was recognised by the 1965 UK Brambell Committee Report. The report further suggested that the extent to which animals live life in the present moment has a major impact on their capacity for suffering. Limited ability to recall previous events and imagine future ones would protect animals from the worry, ‘rumination’ and associated emotional disorders that contribute so much to human suffering. We investigate these suggestions in the light of new evidence on the capacity of animals to travel mentally through time, and with reference to the subjective experiences of human amnesic patients who are indeed ‘stuck in time’, living their lives in the present. The key human abilities for mental time travel are episodic memory and episodic future thinking, characterised by an ability to place events in time (what, where, when (www)), and to consciously recall or imagine these events. Tests of www memory, recollection vs. familiarity memory, single-trial learning, episodic vs. semantic encoding, and forward planning have been used to investigate whether such cognitive systems also exist in animals. The evidence indicates that some studied species show behaviour consistent with the capacity for mental time travel, while others do not. The extent to which animals consciously experience mental time travel remains unknown. In terms of the implications for welfare, research on human amnesics with damage to brain structures involved in episodic memory suggests that animals lacking mental time travel would miss the beneficial consequences of using previous experience to plan and organise future behaviour, but also the detrimental consequences of being able to ruminate on the recalled past and worry about the imagined future. Emotional responses, including future-directed anxiety would be temporally bound by the presence of relevant stimuli or cues and, therefore, potentially short-lived. However past experiences could, through the actions of non-episodic memory systems attributable to other brain structures, still impact on emotional state via (implicit) learning of associations between cues and emotional events. Cumulative effects of past experience on stress response mechanisms and baseline stress or mood states would also be expected to occur. Mental time travel may thus bring both welfare benefits and problems. Absence of this ability by no means releases animals from many effects of the environment, including the past, on their emotional state.