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Mechanization of Cognition 85

one symbol (which then becomes active) is a final decision made at that level. Similarly, only at the
point where the expected word duration has been reached does the next-word acoustic lexicon make
a decision (or, it can even transfer a small expectation back to the language module – which is one
way that robust operation can be aided).
Figure 3.8 illustrates the consensus building process on the next-word acoustic lexicon as the S
vector is directed to each subsequent primary sound lexicon in turn. As honed expectations are
transferred upward, the expectation of the next-word acoustic lexicon is itself honed. This honed
expectation is then transferred downward to refine the expectations of the as-yet-unresolved sound
phrase and primary sound layer lexicons. These consensus building interactions happen dynamic-
ally in continuous time as the involved operation commands are slowly tightened. This again
illustrates the almost exact analogy between thought and movement. As with a movement, these
smoothly changing, precisely controlled, consensus building lexicon operate commands are

Figure 3.8 Consensus building process on the next-word acoustic lexicon (see Figure 3.7). Initially, symbols in
the next-word expectation (green dots in the left-most representation of the lexicon state) are established by
knowledge link inputs from the speaker model lexicon and from the language module. As consensus building
progresses, transfers of honed expectations from sound phrase lexicons (which themselves are receiving transfers
from primary sound lexicons) hone this initial expectation, as illustrated here moving from left to right. Yellow-filled
circles represent symbols that were not part of the initial expectation. These are locked at zero excitation. The color
chart on the left shows the positive excitation scale from lowest on the bottom to highest on top. Some of the initial
expectation symbols become progressively promoted to higher levels of excitation (the sum of all symbol excita-
tions is roughly constant during consensus building). Others go down in excitation (it is possible for a symbol to
change nonmonotonically, but that is not illustrated here). In the end state of the lexicon (far right) one symbol (red)
has become active — this symbol represents the word that has been detected. Keep in mind that in a real
architecture there would typically be tens of thousands of symbols and that only a few percent, at most, would
be part of the initial expectation.