Aging, parafoveal preview, and semantic integration in sentence processing: testing the cognitive workload of wrap-up.

The current study investigated the degree to which semantic-integration processes ("wrap-up") during sentence understanding demand attentional resources by examining the effects of clause and sentence wrap-up on the parafoveal preview benefit (PPB) in younger and older adults. The PPB is defined as facilitation in processing word N + 1, based on information extracted while the eyes are fixated on word N, and is known to be reduced by processing difficulty at word N. Participants read passages in which word N occurred in a sentence-internal, clause-final, or sentence-final position, and a gaze-contingent boundary-change paradigm was used to manipulate the information available in parafoveal vision for word N + 1. Wrap-up effects were found on word N for both younger and older adults. Early-pass measures (first-fixation duration and single-fixation duration) of the PPB on word N + 1 were reduced by clause wrap-up and sentence wrap-up on word N, with similar effects for younger and older adults. However, for intermediate (gaze duration) and later-pass measures (regression-path duration, and selective regression-path duration), sentence wrap-up (but not clause wrap-up) on word N differentially reduced the PPB of word N + 1 for older adults. These findings suggest that wrap-up is demanding and may be less efficient with advancing age, resulting in a greater cognitive processing load for older readers.