Depth of lexical-semantic processing and sentential load

The text-change detection task has been used to show that changes are more readily detected for words that fall under narrow focus than broad focus (Sturt, Sanford, Stewart, & Dawydiak, 2004), and that narrow focus appears to lead to finer semantic distinctions being held in the representation of the word. The present experiments apply the same paradigm to investigate whether sentence processing load also influenced the detection of changes, and whether under a high load, semantic distinctions are held at a more crude (rougher grain) level than under low load. Load comparisons were made through subject- and object-extracted relative clauses (Experiment 1), and through referential load (Experiments 2 and 3). Higher loads resulted in poorer change detection, but the pattern of data differed from that obtained in focus manipulations. Experiment 4 explored the effects of referential load upon comprehension, confirming that comprehension did not break down under high-load conditions. In Experiment 5, the load effect was localized to the embedded verb. These results suggest that the effect of load differs from the effect of focus on lexical processing.