Frequency effects in the auditory grammatical decision task

We investigated effects of phrase-frequency and the frequency of content words in two auditory grammatical decision experiments testing grammatically correct 4-word phrases intermixed with ungrammatical 4-word sequences. A significant phrase-frequency effect was found in Experiment 1 while controlling for syntactic structure (the sequence of parts-of-speech) and word-frequency. No effect of word-frequency was found in Experiment 2 when controlling for phrase-frequency and syntactic structure. A third experiment measured the cloze probability of the final words of the grammatically correct phrases tested in Experiments 1 and 2. Although entering cloze probability as a covariate rendered the effect of phrase-frequency non-significant, a re-analysis of a subset of phrases matched for cloze probability revealed a significant effect of phrase-frequency, while the effect of word-frequency remained non-significant.