Lexical access enhances the activation of predominant stress templates in infants

Infants develop different kinds of long-term linguistic representation as early as in their first year of life. We examined the interaction of early lexical access and prosodic processing. It is proposed that familiar word forms are stored in a protolexicon before linking any concepts to them, enabling early (proto)lexical segmentation from fluent speech. Additionally, previous results strengthened the fundamental contribution of speech prosody to segmentation in infants. Electrophysiological data show that the discrimination of illegal stress pattern elicits mismatch responses in infants, while stimulus with a legal stress pattern does not. We assessed event related brain potentials reflecting assumed interaction between prosodic processing and lexical access. We hypothesised that significant neural responses might appear for the predominant stress pattern, when familiar words are presented. We investigated 10 (35) and 6 (17) months old infants presenting two stress variations of a frequent word in an acoustic passive oddball paradigm (400 items, deviant: p=25%). We compared results to earlier data using pseudoword: ERPs to the familiar word with predominant stress pattern showed enhanced brain responses compared to the pseudo-word. We interpret this finding as elaborated and more flexible processing of words stress when lexical cues are available in this stage of development.