How do individual cognitive differences relate to acceptability judgments ?

Sprouse, Wagers, and Phillips (2012) carried out two experiments in which they measured individual differences in memory to test processing accounts of island effects. They found that these individual differences failed to predict the magnitude of island effects, and they construe these findings as counterevidence to processing-based accounts of island effects. Here, we take up several problems with their methods, their findings, and their conclusions. First, the arguments against processing accounts are based on null results using tasks that may be ineffective or inappropriate measures of working memory (the n-back and serial-recall tasks). The authors provide no evidence that these two measures predict judgments for other constructions that are difficult to process and yet are clearly grammatical. They assume that other measures of working memory would have yielded the same result, but provide no justification that they should. We further show that whether a working-memory measure relates to judgments of grammatical, hard-to-process sentences depends on how difficult the sentences are. In this light, the stimuli used by the authors present processing difficulties other than the island violations under investigation and may have been particularly hard to process. Second, the Sprouse et al. results are statistically in line with the hypothesis that island sensitivity varies with working memory. Three out of the four island types in their experiment 1 show a significant relation between memory scores and island sensitivity, but the authors discount these findings on the grounds that the variance accounted for is too small to have much import. This interpretation, however, runs counter to standard practices in linguistics, psycholinguistics, and psychology.*