The differential effects of direct and indirect speech on discourse comprehension in Dutch and English listeners with and without aphasia

Abstract

Background: In a previous study, we demonstrated that narratives containing direct speech constructions were easier to comprehend than narratives with indirect speech constructions for Dutch listeners with and without aphasia. There were two possible explanations for this finding: either that direct speech has increased liveliness compared to indirect speech or that direct speech is less grammatically complex.

Aims: This study aimed to provide further insight into the mechanisms underlying the differences between direct and indirect speech constructions on discourse comprehension in Dutch. More specifically, it aimed to examine the role that the grammatical characteristics of direct and indirect speech play in discourse comprehension success by comparing English- and Dutch-speaking individuals with and without aphasia.

Methods & Procedures: An English version of the Dutch iPad-based Direct Speech Comprehension (DISCO) test was developed. Twenty individuals with aphasia and 19 neurologically healthy control participants were presented with spoken narratives that contained either direct or indirect speech constructions. Their performance was compared to that of the participants of the Dutch DISCO study. To assess the effect of language on performance, we conducted a single analysis in which we contrasted the English data with the Dutch data.

Outcomes & Results: Control participants performed better than participants with aphasia; English-speaking participants performed worse than Dutch participants, and narratives containing direct speech were easier to comprehend than narratives with indirect speech constructions. However, a subsequent analysis including only individuals with aphasia showed that the Dutch group differed from the English-speaking group: direct speech was only beneficial for the Dutch participants with aphasia.

Conclusions: This study expanded on the findings of a previous study, in which a facilitating effect of direct over indirect speech constructions for audiovisual discourse comprehension was found. The differential effects of direct speech on comprehension in Dutch and English showed that rather than one or other explanation being “correct”, both liveliness and grammatical characteristics play a role in discourse comprehension success. Grammatically less complex constructions (direct speech) are not necessarily always easier to comprehend than grammatically more complex constructions (indirect speech) for individuals with aphasia. In our study grammatically simple constructions introduced grammatical ambiguity and therefore possible interpretation difficulties for the English-speaking participants with aphasia.

Keywords:

• aphasia
• discourse comprehension
• direct speech
• indirect speech

Notes

1. Macquarie University Human Research Ethics Committee approved the study, and all the participants provided signed informed consent prior to participation.

2. The FRE test is designed to indicate comprehension difficulty, based on the number of words, sentences, and syllables of a narrative. Higher scores indicate material that is easier to read. Texts with scores between 60 and 69 are considered standard, those between 70 and 79 fairly easy, and those between 80 and 89 easy (Flesch, 1948).

3. During this test, the participant receives instructions to perform tasks that increase in difficulty with a set of tokens differing in shape, colour, or size, such as “show me the red square and the yellow circle”.

4. There was not enough support to distinguish the English-speaking participants with aphasia from the other groups in the analysis including the NBD participants. The AIC reduction of the more complex model including the contrast (over the model reported in Table 6) was 1.4, and the interaction term was only marginally significant (p = .06).

Additional information

Funding

This work was part of the research program The Conversation Frame: Linguistic Forms and Communicative Functions in Discourse, awarded to Dr. Pascual, and financed by the Netherlands Organisation for Scientific Research (NWO) [grant number 276.70.019]. Lyndsey Nickels was funded by an Australian Research Council Future Fellowship [grant number FT120100102].