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

3.3 A Model of RC Processing
Relative Clause Experience
Figure 2. Comparison of the Human Self-Paced Reading Patterns at Pre- and Post-test to the GPE Patterns Obtained for the SRNs.
Figure 3.5: Wells et al. (2009) reading times compared to modeling results of MacDonald
and Christiansen (2002)
The unnatural ORC patterns are probably the reason for an experience effect over
such a short interval of only 4 weeks. 37 Additionally, unnaturalness might have inflated
the clause type effect in reading times. I suspect that a study with completely natural
sentences would show a smaller clause type difference and would need a strongly extended
training period to show experience effects. However, this small-scale study clearly proves
the effect of structural probabilistic constraints on reading skill. The comparability with
the SRN simulations is given by the transitivity constraint in ORCs which is a probable
factor both in the simulations and in the human study.
A Detailed Prediction Analysis
The assumption that the SRN mainly learns the verb transitivity in ORCs is, however,
only speculation. Konieczny and Ruh (2003) carried out a more detailed analysis of
the word-by-word predictions of MC02’s SRN. They found that the high GPE scores on
the embedded verb in the ORC and the matrix verb in both RC types were caused by
lexical misclassifications and local coherence. In particular, seeing the ORC sequence
‘the N that the N’ the SRN predicts the end-of-sentence marker EOS in early training.
In later epochs the activation on EOS is reduced and increased on the correct verbs.
Notably, the predictions for incorrect verbs (in this case all intransitive verb plus those
with non-matching number) do not change over training. This pattern is inconsistent
with the transitivity hypothesis. The experience-based decrease of error on the ORC
embedded verb is seemingly not caused by learning the distinction between transitive
and intransitive verbs but rather by learning to separate the pronoun that from verbs.
The other region showing effects of clause type and experience is the main verb. At
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