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<Paper uid="W98-0306">
  <Title>trast and Violated Expectation, Sanders et al.'s Contrastive Cause-Consequence, Contrastive Consequence-Cause, Contrastive Argument- Claim, Contrastive Clalm-Argument, Oppo-</Title>
  <Section position="3" start_page="37" end_page="39" type="intro">
    <SectionTitle>
2 Experiment 1: The role of
</SectionTitle>
    <Paragraph position="0"> discourse markers in comprehension If connectives play a significant a role in directing the receiver toward the reconstruction of a discourse relation, their presence should result in a higher rate of correct recognition of relations, while their absence should determine a significant worsening in the recognition ability; also, relations different from the original ones may be inferred more easily.</Paragraph>
    <Section position="1" start_page="37" end_page="37" type="sub_section">
      <SectionTitle>
2.1 Methodology and Data Collection
</SectionTitle>
      <Paragraph position="0"> In Experiment 1 subjects had to label the relation perceived between two textual segments, presented in two different versions, either with or without the original connective.</Paragraph>
      <Paragraph position="1"> The material for the experiment consisted of two sets of 72 pairs of discourse segments, embedded in a larger context. The segments were taken from a corpus of written texts, of various genres; all items were in Italian. In the &amp;quot;with connective&amp;quot; version, the segments had not been altered; in the &amp;quot;without connective&amp;quot; version, the original text was modified as little as possible. The segments had been chosen in order to form a representative set of the three classes of coherence relations (21 examples for the additive type, 27 for the consequential type, and 24 for the contraztive type; attribution of actual instances to types was made on the basis of the taxonomy in section 1), as well as to display a vast range of connectives for each type of relations.</Paragraph>
      <Paragraph position="2"> The subjects were ten undergraduate students. Subjects were instructed to spontaneously label the relation they perceived between the two segments. A half of the subjects had to read 36 examples with the connective and 36 without: the other half had to read the same examples, in inverted order.</Paragraph>
    </Section>
    <Section position="2" start_page="37" end_page="39" type="sub_section">
      <SectionTitle>
2.2 Results and Discussion
</SectionTitle>
      <Paragraph position="0"> The data were analyzed according to the following criteria. For each type of relation, we determined the number of cases where the relation between the segments was correctly inferred, either with connective and without connective. A relation was considered to be correctly inferred when the spontaneous label chosen matched our taxonomy-based classification.</Paragraph>
      <Paragraph position="1"> Those cases where the relation was not correctly  retrieved were further classified in uncertainty instances and confusion instances (i.e., when subjects attributed the relation to a different class). Table 1 illustrates the data for each of the three classes of coherence relations.</Paragraph>
      <Paragraph position="2"> The degree of correctness in the answers is taken to be representative of the degree of comprehension of the relations. The data confirm our hypothesis that a connective facilitates the interpreters' ability to infer the relation intended by the message sender. For all types of relations, the absence of the connective corresponds to a reduction in the number of correct answers. However, this reduction displays distinct patterns according to the type of relation involved. The contrastive type shows the highest reduction, while the additive type the lowest. The consequential type holds an intermediate position. Similarly, the different types of relations are not equally affected by the presence/absence of a connective: additive relations seem to be less comprehensible than contrastive and consequential relations; however, they are those which are best comprehended when lexical signalling is missing.</Paragraph>
      <Paragraph position="3"> The difficulty with which a contrastive relation is inferred without a connective could be due to the fact that lexical marking is essential for the inference of the contrastive component of meaning. According to our hypothesis, the contrastive type should be cognitively more complex than the other two, since it involves an additional negative component. If there is lack of marking, the negative or contrastive component of the relation is lost and the relation is thus interpreted as an additive or consequential relation, according to the underlying type, as it is shown by the redistribution into these other two classes.</Paragraph>
      <Paragraph position="4"> Lexical marking seems not to have a fundamental role for guiding the inference of additive relations: in fact, there is only a slight difference between the number of correct answers in the condition with connective and those in the condition without connective. This could be due to two different, non competing factors: first, it could be that additive connectives are not particularly efficient for guiding the inference of the relation because of their intrinsic ambiguity. Second, it could also be the case that interpreters tend to instantiate whenever possible a &amp;quot;stronger&amp;quot; implicational relation between two segments. Numerous studies (of., among others, Townsend and Bever, 1978; Trabasso and Sperry, 1985; Trabasso and van den Broek, 1987; Garnham et al., 1996; Noordman and Vonk, 1997) suggest that the various types of relations differ not only along the dimension of cognitive complexity, but also along the dimension of cognitive relevance. According to * these studies, causal and temporal relations are cognitively more relevant since they promote the storage in memory of the connection between information.</Paragraph>
      <Paragraph position="5"> On the other hand, the ease with which an additive relation is inferred when there is no lexical marking to signal it could be explained by the fact that a relation of this type is inferred by default, since it signals a simple and general continuation without ally other particular connotation.</Paragraph>
      <Paragraph position="6"> Consequential relations, while showing a reduction in the number of correct answers from the condition with connective to the condition without connective, display a relative ease of comprehension.</Paragraph>
      <Paragraph position="7"> This is not plausibly explained by making reference to the basic common knowledge shared by writers and readers, since this should determine a good recognition of contrastive relations as well. It is more advantageous to hypothesise that the high degree of understanding of consequential relations is related to the well-known preference toward inferring an implicational relation between the segments (el. for example Black and Bern, 198!). Again, the fact that this class of relations is the best comprehended one whith lexical signalling is explainable in terms of semantic non-ambiguity of the connectives usually  employed for its expression.</Paragraph>
      <Paragraph position="8"> In sum, Experiment 1 supports the hypothesis that connectives have a facilitating effect for the inference of the relations intended by the message sender. The fact that not all types of relations are equally facilitated by a connective has been interpreted as the result of three different phenomena: a) semantic ambiguity of connectives for the additive class vs. non-ambiguity of connectives for the consequential and contrastive classes; b) higher cognitive complexity of the contrastive type of relations and hence necessity of connectives for the understanding of the contrastive meaning; c) different cognitive relevance of the different classes of relations.</Paragraph>
    </Section>
  </Section>
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