Cognitive Semantics : Meaning and Cognition

188 JORDAN ZLATEV
respond by giving the red car, in analogy to the red ball and the blue car. But,
then again, the child may make a mistake, and the parent will have to correct
it: “No, not the blue car, the red car” — and the process of training will
continue. Once the child has mastered the distinctions in this game, it can
generalize and use this ability in other games: it will be able to draw red suns
and blue moons, but not because it has formed some “context-independent”
concept of REDNESS, but because new uses constantly draw on old ones, in the
accumulative ability to use language appropriately in ever new contexts.
A number of experiments with the extended version of Regier’s system
(cf. Figure 4) were performed in order to lend some empirical support for this
view and against Chomsky’s “anti-generalization” position. The system was
trained on some, but not all verb-preposition pairs, e.g., on the pairs “be
over”, “be under”, “go over”, “go under” and “fly over”, but not on the sixth
remaining pair “fly under”. 4 The hypothesis was that from using “under” in
two other contexts and “fly” in one other, the system would generalize and
when presented with a novel kind of situation, a trajector flying under a
landmark the system would (by analogy) “light up” the two appropriate nodes:
“fly” and “under”.
The first results were very encouraging. When presenting a set of 30
novel fly under-situations, we found that only 2 were classified as “go under”,
all others were correctly classified as “fly under”. However, when testing the
ability of the net to generalize to other novel word-pairs, e.g., “go over” (after
training on all the rest), we found that the net performed less well — there
were many overgeneralizations (“false alarms”) and even worse, many undergeneralizations
(“misses”). A natural conclusion was that the environmental
“evidence” was insufficient, i.e. the system needed to “see” a larger
number of different over and under situations before it could extract a more
adequate notion of the semantic contribution of the individual words. Therefore
I gradually extended the training to include situations that can be described
with other verbs and prepositions. The most extensive training session
was performed for the verbs: “be”, “move”, “pass” and “fall” and the
prepositions “over”, “under”, “in”, “through” and “on”. The choice of the
words was motivated by following the naming of example “movies” by a
native speaker of English. However, the results were negative: not only did
extending the context of use not make the generalization better, it seemed to
make it worse. In most cases a novel situation would be classified not with a
novel expression but with the non-novel expression used to label some similar