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

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4.2 Replication <strong>of</strong> Previous Simulations<br />

activation and a penalty for misses (4.5).<br />

Hits (correctly activated units): H = <br />

False Alarms (<strong>in</strong>correctly activated units): F = <br />

mi =<br />

i∈Gui<br />

i∈U ui<br />

<br />

0 if ti − ui ≤ 0<br />

ti − ui otherwise<br />

Misses (units with underestimated activation): M = <br />

i∈G(H + F )mi<br />

H<br />

GP E = 1 −<br />

H + F + M<br />

(4.1)<br />

(4.2)<br />

(4.3)<br />

(4.4)<br />

(4.5)<br />

A Perl rout<strong>in</strong>e controlled tra<strong>in</strong><strong>in</strong>g and test<strong>in</strong>g <strong>of</strong> the ten networks and then calculated<br />

the region-specific GPEs. The correct function<strong>in</strong>g <strong>of</strong> the process will now be validated<br />

by the replication <strong>of</strong> two previous studies.<br />

4.2 Replication <strong>of</strong> English and German RC Process<strong>in</strong>g<br />

I built the model with the parameters specified by MacDonald and Christiansen (2002)<br />

and tried to replicate their results (see figure 3.3 for MC02’s results). MC02 report an<br />

RC probability <strong>of</strong> 0.05. However, the replication fitted their data better when the RC<br />

probability was set to 0.1. Konieczny and Ruh (2003) also replicated MC02 with an RC<br />

probability <strong>of</strong> 0.1. Figure 4.1 shows the replication result. The pattern <strong>of</strong> MC02 was<br />

more exactly matched <strong>in</strong> epochs 3, 4, and 5 but the relevant <strong>in</strong>teractions were also found<br />

<strong>in</strong> epochs 1, 2, and 3. Only the tra<strong>in</strong><strong>in</strong>g effect on the ma<strong>in</strong> verb <strong>in</strong> the ORC was not<br />

very pronounced. The differences were, however, significant.<br />

I used the simplified German grammar from Konieczny and Ruh (2003) to replicate<br />

their results. Compared to the orig<strong>in</strong>al study I ga<strong>in</strong>ed lower error rates for the ma<strong>in</strong> verb<br />

<strong>in</strong> both conditions. Additionally the replication showed a significant experience effect <strong>in</strong><br />

all regions <strong>of</strong> the SRC, which was not the case <strong>in</strong> the orig<strong>in</strong>al. The pattern by region<br />

was successfully matched.<br />

I will not go <strong>in</strong>to details regard<strong>in</strong>g the two replication studies. They just build the<br />

basis for the follow<strong>in</strong>g simulations, mak<strong>in</strong>g sure that the model used here has similar<br />

properties as the models <strong>in</strong> MacDonald and Christiansen (2002) and Konieczny and Ruh<br />

(2003).<br />

65

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