Embodiment and the Inner Life
Cognition and consciousness in the space of possible minds
Murray Shanahan
Embodiment and the Inner Life
(Oxford University Press, 2010) weaves together a number of themes from the
philosophy of mind, cognitive psychology, and neuroscience, in an attempt to
form a seamless theory of the mind and its place in Nature, a theory in which
consciousness, cognition, and embodiment are all given their due. Here are
eight of the bookÕs central ideas.
1. The lure of philosophy
How could human thoughts and feelings, the subjective, private
character of a personÕs inner life, possibly be amenable to scientific
explanation? IsnÕt there, ultimately, an unbridgeable metaphysical divide
between our private selves and the physical world we inhabit? In his later
philosophy, Ludwig Wittgenstein managed to escape from this dualistic way of
thinking. But contemporary philosophers and scientists studying consciousness
have largely neglected Wittgenstein, and Embodiment and the Inner Life seeks to put this right.
2. Embodiment
A complex environment affords an animal more possibilities for
action than can be hard-wired into its brain. Embodiment and the Inner Life takes the stand that cognition is inherently
embodied insofar as its fundamental role is to modulate an animalÕs
sensorimotor interaction with its environment. Cognition does this by
discovering new possibilities for action, either by experiment or through
imagination, and introducing them into the animalÕs repertoire. It follows,
according to the theory of the book, that an intimate link exists between
cognition and consciousness. Specifically, the conscious condition facilitates
the exploration of previously untried action combinations, which is especially
beneficial in novel situations.
3. The space of possible minds
Given that it makes sense to approach consciousness using the
scientific method, what sort of theory should we seek? Are we looking for a
theory of the human mind, of
consciousness in humans alone? If we are looking for a deep theory, something
as potent as, say, the theory of evolution by natural selection in biology,
then it must surely encompass other animals. Certain birds, notably rooks and
crows, are capable of remarkably intelligent behaviour, even though their
brains are organised quite differently from our own. The brain of an octopus,
another cognitively precocious animal, is even more alien. Embodiment
and the Inner Life articulates a high-level
theory of cognition and consciousness that is not constrained by specific biological
details.
4. The conscious condition
Much of our waking lives is devoted to habitual, automatic
behaviour, such as driving or cleaning our teeth. But the episodes in our lives
that matter to us most are those that we can remember, that we can talk about,
that we respond to emotionally, the epsiodes that engage us fully, in short the
conscious episodes. Building on the pioneering work of Bernard Baars, Embodiment
and the Inner Life accounts for the
distinction between automatic behaviour and the conscious condition in terms of
a contrast between localised brain activity and globally integrated neural
states in which the whole brain, indeed the whole person (or animal), is
brought to bear on the ongoing situation.
5. Brain connectivity
How might the brain be organised so as to realise the globally
integrated states that are hypothesised to be the hallmark of the conscious
condition? According to Embodiment and the Inner Life, the key is to understand the pattern of long-range
neural connections that constitute the brainÕs communications infrastructure.
These connections enable information and influence from around the brain to
funnel into a connective core, from where it can be broadcast back out again.
Thanks to the structure of this connective core, which acts as a global
neuronal workspace, a serial procession of thoughts is distilled from the
activity of massively many parallel processes, and unity arises out of
multiplicity.
6. Synchronised brain rhythms
Like waves created by raindrops falling into a pool from the many
branches of an overhanging tree, the electrical activity of the brain displays
exquisitely patterned interacting rhythms. Among these patterns, episodes of
synchronised activity can be discerned at multiple frequencies, across widely separated
sites. Drawing on recent findings in neuroscience, Embodiment and the Inner
Life proposes that long-distance
synchronised activity is a signature of the conscious condition, indicating
that a coalition of brain processes is co-operating and communicating via the
global neuronal workspace (connective core), to the exclusion of rival
coalitions.
7. Fluid cognition
One hallmark of sophisticated cognition is the ability to respond
to novelty by effectively recombining the elements of an established behavioural
repertoire. In terms of neural dynamics, this amounts to the capacity to
explore an open-ended repertoire of coalitions of distributed brain processes.
According to Embodiment and the Inner Life,
this is facilitated by the conscious condition, wherein new coalitions of brain
processes can form thanks to the involvement of the global neuronal workspace,
which allows channels of communication to open up between pairs of brain
processes that are not already associated.
8. The inner life
An animalÕs interaction with the world can be thought of in terms of a loop: the animalÕs senses influence its actions, its actions influence the world, and the world in turn influences its senses. Embodiment and the Inner Life advances the notion that this outer loop is complemented by an internal sensorimotor loop, in which the arc from motor activity to sensory activity is closed within the brain itself. Thanks to this internal loop, an animal can rehearse possible actions before carrying them out. The dynamics that results when such the internal sensorimotor loop is combined with a global neuronal workspace is potent, and inaugurates the life of the imagination, as well as inner speech, reason, and reflection.