Mazor, M., Brown, S., Ciaunica, A., et al. (2022)
Perspectives on Psychological Science, 0(0).
Abstract
A target question for the scientific study of consciousness is how dimensions of consciousness, such as the ability to feel pain and pleasure or reflect on one’s own experience, vary in different states and animal species. Considering the tight link between consciousness and moral status, answers to these questions have implications for law and ethics. Here we point out that given this link, the scientific community studying consciousness may face implicit pressure to carry out certain research programs or interpret results in ways that justify current norms rather than challenge them. We show that because consciousness largely determines moral status, the use of nonhuman animals in the scientific study of consciousness introduces a direct conflict between scientific relevance and ethics—the more scientifically valuable an animal model is for studying consciousness, the more difficult it becomes to ethically justify compromises to its well-being for consciousness research. Finally, in light of these considerations, we call for a discussion of the immediate ethical corollaries of the body of knowledge that has accumulated and for a more explicit consideration of the role of ideology and ethics in the scientific study of consciousness.
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The animal-models-of-consciousness paradox
An instance in which the scientific community has failed to acknowledge the intimate link between consciousness and ethics is in the use of animal models of consciousness. Our focus here is on the use of animals that are assumed to be conscious as an opportunity to probe the underlying mechanisms of consciousness in ways that would not be ethically acceptable with human subjects. In such studies, animals are often captive and deprived of basic needs and undergo invasive procedures. At the same time, for these animals to be appropriate models for the study of consciousness, it has to be assumed that they are conscious. Because conscious capacities play a pivotal role in the attribution of moral status to animals, in these experiments, scientific validity and moral justification are in direct conflict. This conflict is particularly acute in the study of consciousness and subjective experience: That an animal is an adequate model for the study of consciousness makes it more likely to be capable of experiencing rich phenomenal states, self-awareness, or suffering and to have its life considered to be deserving of appropriate protection much more than being an appropriate model for the study of the immune system does.
In a recent study of the neural correlates of consciousness, researchers contrasted brain activation in awake, sleeping, and anesthetized macaque monkeys (Redinbaugh et al., 2020). For this study, two monkeys were kept in captivity, implanted with brain electrodes, and immobilized by sticking rods in a head implant during electrophysiological recordings. In another study from 2021, a behavioral measure of conscious awareness was reported in four caged rhesus monkeys (Ben-Haim et al., 2021). Scientists surgically implanted subjects with a metal extension to their skull for the purpose of restraining movement during experimental sessions and restricted subjects’ access to water at testing so that they were motivated to participate in the task for juice droplets. In a study from 2019 on the neural basis of introspection, researchers abolished parts of the prefrontal cortex of six caged macaque monkeys, which were killed at the end of the study (Kwok et al., 2019). In another study published in Science in 2020 (Nieder et al., 2020), a neural correlate of sensory consciousness was demonstrated in the brains of two male crows by implanting electrodes in their brains. These are mere examples of typical research practice in the field of invasive electrophysiology that conform with current ethical guidelines in place at a national level and are commonplace in many fields of study. Yet common to these studies is that their scientific relevance rests on the animal being conscious, whereas their ethical justification rests on the animal not deserving the same protection from suffering as a human subject.
