Measuring processing load during sentence comprehension: Visuomotor tracking

This investigation examined processing load during aspects of sentence comprehension in non-brain-damaged subjects. Our goals were to begin the process of quantifying the loads associated with on-line and off-line aspects of sentence processing and to evaluate the utility of visuomotor tracking as an index of the resource demand associated with elements of sentence comprehension. Subjects were required to track an unpredictable visual target with their forefinger while listening to sentences and answering Yes-No comprehension questions. In general, tracking performance declined during the off-line task of responding to questions compared to the on-line task of listening to sentences and questions. Performance was also poorer during the beginning and end of the sentence compared to the middle of the sentence. Results are discussed in relation to resource theories of normal and aphasic sentence comprehension.