Connectionist Modeling of Experience-based Effects in Sentence ...

Chapter 3 Connectionist Modelling of Language Comprehension
Experience Account (p. 44) that attacks the modular picture of knowledge and
memory. The crucial claim of MC02 is that differences in performance result from processing
skill as a function of experience and not a separable WM capacity.
“In our view, neither knowledge nor capacity are primitives that can vary
independently in theory or computational models; rather they emerge from
the interaction of network architecture and experience.” (p. 37)
The subsymbolic (and behavioristic) nature of connectionist networks make grammatical
knowledge and processing indistinguishable. A change in parameters like weight
vectors or hidden layer size is not attributable to one of the two components. Rather
either affects the behavior of the whole network.
3.3.2 Critique and Relation to other Approaches
MC02 see their model as an opposition mainly to models like Just and Carpenter (1992)
and Waters and Caplan (1996), which explicitly account for memory capacity limitations.
MC02’s SRN simulations have important implications with respect to biological plausibility
of processing models. they demonstrated that there is no need to assume separable
working memory and knowledge modules in order to account for effects attributed to
these. Rather experience shapes the whole system and capacity is a property emergent
from the systems architecture. That emphasizes the role of symbolic models like Just
and Carpenter (1992) as merely higher-level descriptions of underlying processes. There
is, of course, nothing wrong with symbolic descriptions. What is in question, however,
is the justification of explicit numerical limits on capacity. In Just and Carpenters account
the capacity limit is defined as the maximal amount of activation attributed to
productions (processing rules). The latter can be varied without touching the rest of the
system. Arguing with MC02, however, this value is indeed emergent and inseparable
from the entire system. As a consequence sentence comprehension and reading span
measure the same thing, namely reading skill, which is the experience-shaped efficiency
of linguistic processes.
Non-Linguistic Working Memory
Not convinced by this view Roberts and Gibson (2002) note that a pure skill-viaexperience
account would not be able to explain these correlations of comprehension skill
with non-linguistic working memory tasks that do not involve sentence reading. Roberts
and Gibson provide respective empirical evidence for correlations of sentence memory
with several memory load tasks that do not involve reading sentences. Addressing these
correlations MC02 propose that reading skill is tied to phonological representations.
These representations play the crucial role in all sorts of memory load tasks and account
for individual differences. Regarding phonological representations MC02 formulate four
important claims (p.45):
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