A team of researchers has outlined a new approach for better understanding the depths of animal consciousness, a method that may yield new insights into the similarities and differences among living organisms.
The essay, which appears in the journal Science, describes a "marker method" that scientists can use to assess animal consciousness. It involves identifying behavioural and anatomical features associated with conscious processing in humans and searching for similar properties in nonhumans. By making advancements in the science of animal consciousness, the authors propose, we can also make progress on foundational questions about the nature of consciousness, potentially improving our understanding of the human mind.
"When humans and other animals perform similar behaviours, and when the best explanation for these behaviours in humans involves conscious experience, then that could be considered evidence of conscious experience in other animals, too," writes York University Philosophy Professor Kristin Andrews with co-authors Jonathan Birch, a philosophy professor at the London School of Economics and Political Science, and Jeff Sebo, a professor in New York University's Department of Environmental Studies, in the Science essay "Evaluating Animal Consciousness."
The publication comes nearly a year after the "New York Declaration on Animal Consciousness," which demonstrated the scientific backing for consciousness among all vertebrates and many invertebrates, among other species. The declaration, organized by Andrews, Birch, and Sebo, has been signed by more than 500 scientists and researchers around the globe.
Philosophers, including Jeremy Bentham, and scientists, notably Charles Darwin, have considered questions linked to animal consciousness while John Stuart Mill, in the mid-19th century, acknowledged the challenge of broadly assessing consciousness. Well into the 21st century, a secure theory of consciousness remains elusive, and disagreement and uncertainty about the scope of consciousness in the animal kingdom remain ongoing.
In their essay, Andrews, Birch and Sebo describe an approach that includes "identifying a particular dimension of consciousness," such as experiencing pain or seeing an object, and then "seeking evidence that such markers are present (or absent) in the target species." They then call for new directions of inquiry, including research on dimensions of consciousness other than pain experience such as joy and non-invasive research methods.
However, they recognize the limitations of individual markers to serve as strong evidence by themselves. "The degree to which a particular marker can increase or decrease confidence in particular dimensions of animal consciousness depends on context," they write. "For instance, linguistic behaviour is a marker of specific kinds of conscious thought and emotion in humans. But as demonstrated by large language models that simulate human conversation, linguistic behaviour alone is not strong evidence of consciousness in nonhuman systems."
Despite these challenges, the authors emphasize the importance of continued exploration. "The idea that there is a realistic possibility' of consciousness in all vertebrates and many invertebrates may eventually be replaced by more confident language," they conclude. "But for as long as the evidence remains limited and mixed, it is important to keep an open mind and strive to learn more."
