Repetition-attenuation of auditory N1 is modulated by the phonological representations of spoken word-forms

Repeated auditory stimuli are usually found to elicit attenuated peak amplitude of the N1 component of the event related brain potential (ERP). While the repetition-attenuation of the auditory N1 has been found sensitive to some cognitive factors, less is known whether and how the representational properties of stimuli influence this physiological phenomenon. To further address this issue, we focus on the phonological representations of spoken word-forms, and hypothesise modulatory roles of two phonological features: the lexicality and its usage frequency of a word-form. To test this, we used a short-term habituation design with a factorial combination of the two features at two levels each (i.e., lexicality (real versus pseudo word-form) x frequency (high versus low frequency)). EEG was recorded from 30 native Mandarin-speaking participants while they were passively delivered with stimulations trains. Each train consisted of five presentation positions (S1 [~] S5), on which one word-form is presented repeatedly, separated by a brief, constant interstimulus interval. At the fourth presentation position (S4), we found greater N1 attenuation in low-frequency pseudo word-forms than in low-frequency real and high-frequency pseudo word-forms, respectively. The results support our representational modulation hypothesis, and provides the first evidence that representations of different phonological features interactively modulate the N1 repetition-attenuation. The brain function that underlies the phonological effects of the representational modulation on N1 repetition-attenuation might be sensory filtering.