Not all processing difficulties are created equal

A slowdown in reaction time in self-paced reading is typically interpreted as a sign of processing difficulty. Similarly, a low acceptability rating can, among other things, be caused by processing difficulty. The question examined in this article is whether a slowdown in reaction time always affects acceptability negatively. To investigate this, an acceptability study was performed, comparing sentences that only differ regarding the main verb (Mia noticed/presumed the pig in the pen needed water) and where the word-for-word reaction time data in reading is known from previous research. The reaction time data show that both types involve a slowdown, but at different locations in the sentence (at the embedded subject vs. at the embedded verb) and for different reasons (missing complementizer vs. reanalysis). The acceptability ratings show that the two types of slowdowns are not equally costly: The slowdown due to reanalysis causes a significantly lower rating than the slowdown due to a missing complementizer. The result illustrates that not all processing difficulties (measured as a slowdown in self-paced reading) have the same adverse impact on acceptability judgments.