How Should We Study Animal Consciousness Scientifically?
Other sculptors, other statues from the same stone! Other minds, other worlds from the same monotonous and inexpressive chaos! My world is but one in a million alike embedded, alike real to those who may abstract them. How different must be the worlds in the consciousness of ant, cuttle-fish, or crab! (William James, 1890, p. 289)
A conscious being has a subjective point of view on the world and on its own body. This idea of a ‘point of view’ is easiest to grasp in the case of vision. Ernst Mach, in the Analysis of Sensations, famously attempted to draw his own visual point of view. But there is far more to human subjective experience than vision. Our subjective point of view includes sounds, odours, tastes, tactile experiences — a complete sensory world. And these sensory experiences of a world outside us are integrated with bodily feelings, emotions, conscious thoughts, conscious memories, and imagination. This point of view can be contrasted with a great mass of processing that occurs unconsciously, without surfacing in experience. In humans, this mass includes the early stages of sensory processing, as well as many processes of bodily self-regulation and motor control.
Are we alone, or do some other animals also have subjective points of view? In 2012, the ‘Cambridge Declaration on Consciousness’ captured an emerging consensus that ‘non-human animals, including all mammals and birds, and many other creatures, including octopuses’ possess neurological substrates complex enough to support conscious experiences. The declaration signalled that, rather than debating whether any non-human animals have subjective experiences, it is time to move on to the questions of which animals have them — and what forms their experiences take.
Ten years later, a new interdisciplinary field is emerging. Like consciousness science, it draws together many disciplines around a shared set of questions — but the mix of disciplines is somewhat different. To study animal experiences, we need expertise not only from cognitive science, neuroscience, and psychology, but also from animal welfare and veterinary science, comparative psychology, and evolutionary biology. Philosophy also has a crucial role in placing this field on a solid conceptual and methodological footing.
This emerging field faces foundational challenges. To study subjective experience in animals, we need methods that do not rely on animals verbally reporting how they feel. As a result, many methods from human consciousness science cannot be directly translated. But this should be a starting point for debate, not grounds for despair. It should push us harder to do something we already need to do to study consciousness in infants and in patients with disorders of consciousness — develop better ways of studying subjective experience without verbal report. We may one day look back on the idea of using verbal report to study consciousness as akin to measuring the temperature of a liquid by putting a hand in it — as our initial way of latching on to the phenomenon of interest, a starting point, not a measurement technique we can never transcend, or one that works for the full range of cases.
The present special issue of the Journal of Consciousness Studies aims to advance that foundational debate. The editors have invited authors to respond to one of the following key questions:
- How does the evolution of consciousness relate to the evolution of cognition? (Zacks, Ginsburg and Jablonka, this issue; Halina, Harrison and Klein, this issue).
- What is stronger evidence of consciousness in animals: behaviour or neural mechanisms? (Lamme, this issue; Crump and Birch, this issue).
- How can we measure the subjectively experienced side of welfare? (Broom, this issue; Browning, this issue).
- What is the ethical significance of consciousness? (Kammerer, this issue; Lee, this issue).
- Could all life be conscious? (Thompson, this issue).