sensorimotor experience and language

[Elizabeth Bates]

I agree with Edy Veneziano that one should not take the "motor" part
of the sensorimotor equation too literally.  First, let's remember
that the Piagetian insight was SENSORImotor, which is critical to
the argument.  Second, as Edy notes, let's remember that there is
a very active, selective component to sensory activity as well -- and
one that is linked in non-trivial ways to the planning of response,
both phylogenetically and ontogenetically.
We are talking here about the difference between hearing and listening,
seeing and paying attention.  Within the sensory systems of the brain,
the connections going back down from (for example) visual cortex to
the visual thalamus greatly outnumber the connections that bring
information from the thalamus (which is where the eye reports....)
to the cortex.  In other words, perception itself is active, selective,
enhancing some parts of the signal and suppressing others.  But there is
also a tight connection/overlap between active-sensory and covert-motor
systems.  For example, Italian neurophysiologist Rizzolatti has studied
neurons in premotor cortex that fire preferentially when the monkey is
planning an arm movement in one particular direction (a kind of covert
motor analogue to the line-orientation preference cells in visual cortex).
The most interesting finding here for our purposes is that these cells
also fire when the monkey observes someone else making an analogous
arm movement!  These results are relevant to us in language acquisition
on many grounds -- as one of the possible cortical bases to the mysteries
of imitation, and as testimony to the active, action-based nature of
perception and learning.  In the particular cases of motor-impaired
children that we are discussing here, we can certainly eliminate a
literal actions-out-in-the-world interpretation of the sensorimotor
theory of language, but as long as the child is capable of planning
(including eye movements) and active testing of the world in some form,
then the more interesting version of the sensorimotor hypothesis still
stands, with plenty of neurophysiology to back it up. -liz bates