Post-Comatose Disorders of ConsciousnessThere are two ways in which one might use a patient’s performance in a command- following
paradigm to make a case for consciousness. Most fundamentally, one might argue that command-
following is itself good evidence of consciousness. Alternatively, one might argue that whether or
not command-following is good evidence of consciousness, certain command-following para-
digms require the patient to perform cognitive tasks, the execution of which provides good
evidence of consciousness. Consider the Monti et al. (2010) study, in which a patient correctly
answered questions by engaging in either motor imagery or spatial imagery. There is little doubt
that this patient was conscious, but one could plausibly argue that the ascription of consciousness
is justified not because the patient was following commands, but because he was answering ques-
tions correctly, or because his answers indicated that he had access to autobiographical knowledge.
The interesting question here is whether covert command-following is itself robust evidence
of consciousness. This is an important question, for only a small fraction of behaviorally non-
responsive patients who are able to engage in covert command-following are also able to use this
capacity to communicate. Thus, we need to know whether mere command-following provides
us with good reason to regard a patient as conscious.
The authors of the original command-following study left little room for doubt regarding
their answer to this question:
[the patient’s] decision to cooperate with the authors by imagining particular tasks
when asked to do so represents a clear act of intention, which confirmed beyond any
doubt that she was consciously aware of herself and her surroundings.
(Owen et al. 2006: 1402)This position has not gone unchallenged. Some commentators have taken issue with the
assumption that intentional agency is a marker of consciousness, claiming that “consciousness
is univocally probed in humans through the subject’s report of his or her own mental states”
(Naccache 2006). We will set this challenge to one side, for it sets too high a bar on the ascrip-
tion of consciousness given that we routinely ascribe consciousness to non-verbal beings, such
as pre-linguistic infants and non-human animals. A more serious challenge is that even if inten-
tional agency provides robust evidence of consciousness, command-following studies may not
establish that post-comatose patients are capable of intentional agency (Drayson 2014; Davies
and Levy 2016; Klein 2017). Different authors develop this objection in slightly different ways,
but at the heart of their concerns is the claim that the command-following studies show only
that patients are able to act in response to direct perceptual stimulation, whereas genuine inten-
tional agency requires endogenously-generated (that is, stimulus-independent) intentions. Call
this the challenge from intentional agency.
In responding to this challenge, we might begin by noting that it is not entirely clear that
covert command-following is purely stimulus-driven. Although the patient’s mental imagery is
triggered by a command (presumably the patient wouldn’t have imagined herself playing tennis
unless she had been instructed to do so), the imagery is sustained for 30 seconds, and terminates
only when the command, “relax,” is given. It seems unlikely that the patient’s mental imagery
would exhibit this temporal profile if it weren’t being appropriately guided by an intention,
albeit one that the patient has presumably formed as a result of the instructions.
A second and more fundamental response to the challenge from intentional agency is that
the very conception of intentional action that lies behind the challenge is open to dispute.
Proponents of the challenge deny that stimulus-driven actions qualify as genuinely intentional.
We regard this as an overly restrictive conception of intentional action, and would allow actions
that are guided by external stimuli to qualify as genuinely intentional. Consider the kind of