Mahi Hardalupas (University of Pittsburgh), Alessandra Buccella (University of Pittsburgh)
The Extended Mind Theory of cognition (EMT) claims that cognitive processes can be realized, or partially realized outside of the biological body. Unsurprisingly, proponents of EMT have become increasingly interested in brain-machine interfaces (BMIs). For example, Clark argues that BMIs will soon create human-machine “wholes” challenging any principled distinction between biological bodies and artifacts designed to enhance or replace biological functions. If this is what BMIs are capable of, then they potentially offer convincing evidence in favor of EMT.
In this paper, we criticize the claim that BMIs, and especially motor BMIs (EEG-controlled robotic arms, exoskeletons, etc.), support EMT.
First, Clark claims that BMIs incorporated into the so-called “body schema" will stop requiring complex representational resources mediating between neural inputs and motor outputs. If this is the case, then one has good grounds to claim that we should treat BMIs as genuinely extending cognition. However, at least for now, motor control-BMIs do necessarily require mediating representations.
EMT theorists could reply that two systems can be functionally similar even if one requires representational mediation and the other doesn’t.
However, it seems to us that when EMT suggests functional similarity as a criterion to decide whether BMIs genuinely extend cognition, they should mean similarity at the algorithmic level, that is, where more specific descriptions of the mechanisms involved between input and output are given. But at the algorithmic level the differences regarding representational mediation mentioned above matter.
Moreover, research into BMIs seems to take for granted that their success depends on their proximity to the brain and their ability to directly influence it (e.g. invasive BMIs are considered a more viable research program than non-invasive BMIs). This seems in tension with EMT's thesis that it should not make a difference how close to the brain a device contributing to cognitive processes is.
Finally, EMT is a theory about the constitution of cognitive processes, that is, it claims that the mind is extended iff a device constitutes at least part of the process. However, all the evidence that we can gather regarding the relationship between BMIs and cognitive processes only confirms the existence of a causal relation. Therefore, the currently available evidence leaves EMT undetermined.
In conclusion, we claim that BMIs don't support EMT but, at most, a weaker alternative.
