Page 116 - Artificial Intelligence in the Age of Neural Networks and Brain Computing

104 CHAPTER 5 From Synapses to Ephapsis

performed highly coordinated, alternating steps when they were supported with their
feet on slowly moving motorized treadmill.
She proposes that development is the outcome of the self-organizing processes of
continually active living systems, without the need for programming and rules. Self-
organization is not magic; it occurs because of inherent nonlinearities in nearly all of
our physical and biological universes. In dynamic terminology, behavioral develop-
ment may be envisioned as sequences of system attractors of varying stability,
evolving and dissolving over time. Pattern emerges through the cooperativity of
the components alone. New forms appear during development as a series of phase
shifts engendered by the loss of stability of current forms. An example is a disap-
pearance of newborn stepping. At birth, infants can produce reliable cyclic kicking
and stepping, but they soon lose this ability. When the stepping pattern is envisioned
as a product of dedicated reflex network, this loss is difficult to understand, resulting
in ad hoc explanations such as cortical inhibition. Thelen argues that loss of stepping
is closely paralleled by weight gain from subcutaneous fat, necessary for postnatal
temperature regulation. Here changes in the nervous system may well reflect and not
engender changes in the periphery.
Cognitive scientists see the cognitive development as flowing in only one
directiondfrom percepts to concepts to language in a classical reductionist approach.
Thelen sees instead continuous interactions in both directionsdfrom perception to
language and from language to perception. It makes no sense to ask whether one
determines the other, the entrainment is mutual.
Thelen compares this to Watt’s centrifugal governor, stabilizing speed of steam
engine rotation in variable environment. It does a near perfect job because at every
point in time, everything depends on everything else. The raising of the arms, the
motion of the throttle valve, the speed of the flywheel are not connected in a linear
progress. No behavior of the system is prior to, or a progenitor, to another; rather, all
are mutually entrained, simultaneously products and causes in a complex stream of
activity in time.
Governor and throttle-valve.