The Effect of Semantic Similarity is a Function of Contextual Constraint

We investigate how the degree to which a context constrains the words that could occur in a sentence affects the processing of the word that does occur. Roland et al. (2012) found that processing was facilitated when target words were more semantically similar to word alternatives that could have appeared. Because this effect is independent of word predictability, it suggests that comprehenders may have separate expectations for words and more general semantic features. We show that the semantic similarity effect is modulated by the degree of contextual constraint. We found that facilitation due to semantic similarity was greater when contexts were less constraining, and lower when contexts were more constraining, independent of word predictability. We interpret these results as suggesting that in highly constraining contexts, comprehenders may expect specific words, and face difficulties when these expectations are violated, while in less constraining contexts, they may have more general expectations for semantic properties shared between the words that could occur.