How Should We Go About Looking For Invertebrate Consciousness?
The potential consciousness of invertebrates has been widely questioned throughout recent times. Opponents mainly point to the large evolutionary distance between us and them, and their nervous system structures, namely their very different organization and many fewer neurons. Descriptions such as insects being “natural zombies” or “random automata” have emerged: here, the animals are equated to cognitively sophisticated creatures with no conscious experiences. To counter impressive cognitive capacities, the argument often leans on the fact that we can design robots with equal capabilities — but that does not mean they perceive stimuli consciously.
This study set off to investigate the approaches we employ when searching for consciousness in invertebrates. Three main types of methodological strategies were analyzed:
- Theory-heavy approach: Starting with humans, researchers try to develop a well-confirmed, complete theory of consciousness. Then, this theory would be taken as is and applied to establishing whether other animals are conscious.
- Theory-neutral approach: It contrasts the previous strategy by assuming that the former will not work right off the bat The basis is that theories of human consciousness are all too speculative and controversial – we’re simply too far away from reaching a consensus. Instead, the approach is geared towards building up a list of similarities between human and non-human animals and using analogies and inferences to settle disputes about consciousness.
- Theory-light approach: The author argues that both previous methods are unpromising, giving rise to a middle path between them – an approach aiming to make the best of the two worlds and avoiding their pitfalls.
When undertaken, the first approach ensures the presence of consciousness by collecting human experiences of stimuli verbally. This allows us to gather high-quality empirical data, however, such information is, naturally, unattainable when assessing potential consciousness in non-humans. There’s also no information on how much we can weaken the demands for empirical evidence to still confirm the presence or absence of conscious experiences. Hence, the author argues that this theory simply cannot settle disputes about other animal consciousness.
In his book “Tense bees and shell-shocked crabs”, Professor Michael Tye proposed that the second, theory-neutral, approach might provide us with the answers we seek. Here, the evidence present is much weaker – it not coming via verbal accounting at all. Nevertheless, the strategy does not escape reliance on human data, as defenders are unable to point to a solid, non-human evidence-base and thus cannot hope to resolve disputes regarding non-human consciousness.
Meanwhile, the third – also referred to as the ‘facilitation’ hypothesis, compares scenarios when stimuli are perceived consciously vs. unconsciously. Here, the author suggests that there are multiple consciousness-linked cognitive abilities that could be clustered together; that is that there are robust correlations between them. Here, it’s important to understand that, although humans report consciously perceived stimuli, we cannot report unconsciously perceived ones any more than non-humans. There already are some suitable candidate cognitive capabilities which, together, could form clusters indicative of potential conscious experiences in animals incapable of verbal reporting.
- Trace conditioning is a form of classical conditioning where two stimuli are separated by a time gap. The subjects are given a distracting task in between and, when asked later, should exhibit awareness of the relation between the stimuli, and learn the specifics of the time gap.
- Rapid reversal learning involves being able to learn a relationship between two stimuli and to learn opposite relationships later. This suggests that a conscious experience could be behind fast associative learning when an animal faces novel, unpredictable changes.
- Cross-modal learning is the capacity to learn associations across different sensory modalities. For example, when consciously experienced smells are associated with consciously experienced sounds or visuals.
By taking such robust, consciousness-indicating capacities, researchers could determine which abilities are facilitated by conscious perception, all without committing to any particular theory of consciousness. Another important aspect to further the quality of evidence is to show whether such proposed clusters are selectively switched on and off under masking in the same way the phenomenon occurs in humans. Here, masking is the process where the conscious perception of one stimulus is blocked by a conscious perception of another stimulus. In humans, for instance, quiet sounds preceding loud ones are not perceived consciously.
Although the presence of a combination of certain cognitive abilities doesn’t guarantee a being is conscious per se, the author suggests that this may be the strongest sort of evidence we could ever hope to obtain. Bees seemingly tick all three boxes: data suggests that these animals can do full trace conditioning, rapid reversal learning, and cross-modal learning. However, until now, invertebrate cognition has been studied in a rather haphazard fashion, not permitting to fully test the theory-light approach. For instance, we do not know if the relevant cognitive abilities are sensitive to masking or whether (or to what extent) they correlate with each other across animal taxa.
Many animal advocates will be left with more questions than answers – what does this have to do with welfare, one might ask. Currently, we’re uncertain if bees or many other invertebrates are conscious. How should we then treat bees and other insects? It seems prudent to employ the precautionary principle in cases where we already have determined some cognitive capacities, typically linked to consciousness in mammals. But what does that mean in practice? J. Birch argues that we simply do not know how appropriate measures to protect the welfare of, say, bees would even look like. Nonetheless, the overall debate would most definitely benefit from a systematic identification of the proposed ability clusters, their relationships to each other, and their sensitivity to masking. Assembling such an evidence base should be advocated for — only by showing that these animals feel and care for their lives can we possibly hope to start working on future invertebrate welfare standards and regulations.