On the laws of attraction at cocktail parties: Babble noise influences the production of number agreement

Theoretical accounts of the language production process have claimed that grammatical encoding steps during the formulation stage happen in a largely automatic fashion, unimpeded by other cognitive processes. By eliciting agreement attraction errors, our study tested the effect of external distractor noise on the generation of subject–verb agreement in spoken language. We modelled noisy environments with three different speech-free sounds with spectral, or both spectral and intensity modulation characteristics of speech. In silence and unmodulated noise, we found evidence for a plural mismatch effect, where a plural local noun attracts agreement away from a singular marked head noun. Under modulated noise the error patterns changed, and the number of errors increased in cases where the head noun of the preamble was marked for plural. In addition, background noise led to a reduction of speech rate and a reduction of utterance latency. Our results indicate that unspecific, speech-free noise can create a secondary task load which exerts an influence on the grammatical encoding stage of sentence formulation. We suggest that additional load leads to a slowing down of processing and subsequent difficulty to access the correct number information of the head noun when trying to retrieve an inflected verb form. Subjects overcome this difficulty by resorting to default singular marking on the verb. The results of this study challenge previous claims about the informational encapsulation of the grammatical encoding stage.