is done while knowing what the impor-
tant things in the image are. Edges,
movement, and other “eye catching”
things tell the visual system where to
look. Once this phase of detection and
deconstruction is done, the visual sys-
tem can refit to the particular image it is
dealing with and can associate it to the
current context. This gives the stimulus
meaning and achieves a functional im-
age, while widening the knowledge of
the visual world via memory.
The fact that our visual ability is
based on and inseparable from our per-
ception of the general properties of vi-
sual stimuli can easily be seen in the
kinds of illusions that fool us. Movies,
animation, and paintings are all only
good copies of natural images in the
sense that they capture the general
properties of the visual world.
Note the different scales involved in
the two phases that we have discussed
so far regarding vision. The first stage,
the stage of priming and obtaining the
achieved set, is a stage that responds to
some external input, but does so in a
duration orders of magnitude longer
than the time needed to process new
input once the system is fully func-
tional. Moreover, the second stage, spe-
cific interaction, is a continuous pro-
cess going on all the time, whereas the
first stage is a once in a lifetime oppor-
tunity. It takes a long time to put to-
gether an organism, but, once it exists,
the organism has to use its mechanisms
immediately.
One cognitive system where this
separation in time is clearly seen
is in the development of language
in children. As infants and children, we
learn to speak, and it is a long and la-
borious process. However, once lan-
guage is acquired, when we add new
words to our vocabulary, learning them
and their correct use is something that
we can do almost instantaneously. We
will deal with only one aspect of the ac-
quisition of language—the learning of
correct syntactic combinations—how
we know the correct order of words that
make a meaningful sentence. This step
is made possible by the previous stages
of auditory and cognitive development,
which are influenced by various innate
and learned biases. The exact amount
of learned and innate influence is the
scene of many an argument in the cog-
nitive sciences that we will not go into
[7]. In any case, it is obvious that at the
stage of syntactic development the lan-
guage system already has a “tendency”
that sets the stage for the learning of
syntactic combination. This can be seen
in the fact that the learning of sentence
formation is always preceded, in chil-
dren, by a stage of rapid growth in vo-
cabulary or “vocabulary explosion,”
that brings about the creation of the vo-
cabulary necessary for syntactic combi-
nations [8].
In studies concerning the use of in-
transitive and transitive verbs in syntac-
tic combinations, in parents’ conversa-
tions with their children, it was seen
that parents use a very small subset of
verbs at a very high frequency when
talking to their children. Words such as
want, come, go, and make account for
a high fraction of the verbs used in
parental conversation. All these high-
frequency verbs are very general, have
uses that are almost empty semanti-
cally, and can be said to be generic of
FIGURE 3
the verb subcategories to which they
belong. In return, all the first verbs used
by children are drawn from this group
of verbs (though individually each
child’s first verb need not be the most
commonly said word of his parent).
Further, once the first verbs are learned
in a certain syntactic construction, the
speed of learning other verbs in the
same syntactic construction, but not
necessarily in other constructions, is
greatly enhanced. This could be indica-
tive of a scenario where the child learns
the first 2 or 3 examples, after which the
others are greatly facilitated (Reference
9 and Figure 3).
Figure 3. Cumulative number of different verbs in VO and SVO word combinations produced by
a subject as a function of age [9].
In effect, because of the shape space
of languages, in the course of normal
conversation, children are exposed to
the useful example of the different types
of syntactic combinations and the cor-
rect use of language. The first words are
very common and have many uses (they
embody various ideas). In this fashion
the useful examples of language are cor-
roborated, bringing about the forma-
tion of an achieved set of representa-
tions that greatly facilitates the latter
identification of similarities to the use-
© 2001 John Wiley & Sons, Inc.
CO M PLEXITY
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