Conversational understanding (CU) refers to the ability to accurately interpret the meaning of discourse-embedded language. Siegal and Surian (2007) have suggested that the developmental expression of CU often reflects the unmasking of a cognitive competence obscured by processing biases associated with a shortage of computational resources. This thesis sought to investigate the relationship between developing computational resources (conceptualized in terms of executive functioning (EF)) and CU in 3- to 6-year-old children. According to Miyake et al. (2000), EF can be considered to reflect three main skills - inhibition and updating of mental representations, and mental set shifting. This thesis investigated the independent contribution of these three aspects of EF to CU.
Experiments 1 and 2 investigated whether a relationship exists between the three components of EF and a narrow, scalar implicature (SI) measure of CU. Updating ability was found to demonstrate significant relations with SI scores. Experiment 3 revealed that shifting ability is significantly related to a broad, conversational violations task (CVT) measure of CU. Experiment 4 used training to significantly enhance children's shifting ability. However, this did not lead to a corresponding improvement in CVT performance.
Experiment 5 investigated the relationship between EF and CU in bilingual children. Bilinguals demonstrated a non-significant shifting advantage relative to monolingual controls, but did not demonstrate a CO superiority. Experiment 6 provided a more detailed analysis of the relationship between EF and CO by presenting monolingual children with both the narrow and broad CO measures previously presented, along with the updating, inhibitory and shifting EF measures used in Experiments 2-5 and three new measures of these EF components. All three EF components were found to demonstrate relations with CVT performance after the effects of age and verbal intelligence had been controlled for.
The consistent demonstration of significant relationships between EF components and CU revealed in this thesis provides partial support for Siegal and Surian's masked competence model of the developmental expression of CU.