Internally Triggered Experiences of Hedonic Valence in Nonhuman Animals: Cognitive and Welfare Considerations.

Do any nonhuman animals have hedonically valenced experiences not directly caused by stimuli in their current environment? Do they, like us humans, experience anticipated or previously experienced pains and pleasures as respectively painful and pleasurable? We review evidence from comparative neuroscience about hippocampus-dependent simulation in relation to this question. Hippocampal sharp-wave ripples and theta oscillations have been found to instantiate previous and anticipated experiences. These hippocampal activations coordinate with neural reward and fear centers as well as sensory and cortical areas in ways that are associated with conscious episodic mental imagery in humans. Moreover, such hippocampal "re- and preplay" has been found to contribute to instrumental decision making, the learning of value representations, and the delay of rewards in rats. The functional and structural features of hippocampal simulation are highly conserved across mammals. This evidence makes it reasonable to assume that internally triggered experiences of hedonic valence (IHVs) are pervasive across (at least) all mammals. This conclusion has important welfare implications. Most prominently, IHVs act as a kind of "welfare multiplier" through which the welfare impacts of any given experience of pain or pleasure are increased through each future retrieval. However, IHVs also have practical implications for welfare assessment and cause prioritization.

The dimensions of episodic simulation.

Human adults possess the extraordinary ability to produce mental imagery about a wide variety of non-occurrent events. We can, for example, simulate the perception of different places, different times, different possibilities, or others' perspectives. Findings from cognitive psychology, neuropsychology, and cognitive neuroscience suggest that all of these capacities rely on the same neuro-cognitive mechanism: episodic simulation. This ability produces mental imagery by constructively recombining elements of past experiences to simulate event representations. However, if episodic simulation indeed produces mental imagery, it remains unclear how the non-imagistic aspects of its outputs become cognitively determined. In this article, I argue that there are (at least) four such non-imagistic 'dimensions' of episodic simulation: specificity, temporal orientation, subjectivity, and factuality. Further, I propose an account of the mechanisms which might be responsible for determining where a given output of episodic simulation falls within this dimensional space. According to this view, episodic simulation relies on propositional 'scope-operators' either deployed as inputs to the simulation process itself or produced by post-hoc monitoring processes operating over its outputs. This view has consequences for how we should view the operation, development, and evolution of episodic simulation.