Executive control is shared between sentence processing and digit maintenance: Evidence from a strictly timed dual-task paradigm

Abstract

We investigated whether the comprehension of syntactically difficult sentences taxes the executive control component of working memory more than the comprehension of their easier counterparts. To that end, we tested the effect of sharing executive control between sentence comprehension and the maintenance of a digit load in two dual-task experiments with strictly controlled timing (Barrouillet, Bernardin, & Camos, 2004). Recall was worse after participants had processed one (Experiment 2) or two (Experiment 1) difficult sentences than after they had processed one or two easy sentences, respectively. This finding suggests that sentence processing and the maintenance of a digit load share executive control. Processing syntactically difficult sentences seems to occupy executive control for a longer time than processing their easy counterparts, thereby blocking refreshments of the memory traces of the digits so that these traces decay more and recall is worse. There was no effect of the size of the digit load on sentence-processing performance (Experiment 2), suggesting that sentence processing completely occupied executive control until processing was complete.

Keywords:

• Dual-task paradigm
• Executive control
• Sentence processing
• Time-based resource-sharing model
• Working memory

Acknowledgements

This research was made possible by Grant G.0052.08 of the Research Foundation-Flanders to AV, TD, and RJH.

Notes

¹ Answers to comprehension questions on (un)ambiguous pronoun sentences were left out of the analyses of the accuracy data. Questions on this type of sentence checked whether participants had correctly interpreted the pronoun and knew to which of the two persons in the head clause it referred. As the pronoun in sentences with an ambiguous pronoun could refer to either person in the head clause, it could never be misinterpreted and answers to comprehension questions were always correct. On the other hand, the pronoun in sentences with an unambiguous pronoun could only refer to one of the two persons in the head clause and could consequently be misinterpreted. An analysis on the accuracy data for these sentences would thus not be a fair test of performance differences.