ERP correlates of unexpected word forms in a picture-word study of infants and adults

We tested 14-month-olds and adults in an event-related potentials (ERPs) study in which pictures of familiar objects generated expectations about upcoming word forms. Expected word forms labelled the picture (word condition), while unexpected word forms mismatched by either a small deviation in word medial vowel height (mispronunciation condition) or a large deviation from the onset of the first speech segment (pseudoword condition).Both infants and adults showed sensitivity to both types of unexpected word form. Adults showed a chain of discrete effects: positivity over the N1 wave, negativity over the P2 wave (PMN effect) and negativity over the N2 wave (N400 effect). Infants showed a similar pattern, including a robust effect similar to the adult P2 effect. These observations were underpinned by a novel visualisation method which shows the dynamics of the ERP within bands of the scalp over time. The results demonstrate shared processing mechanisms across development, as even subtle deviations from expected word forms were indexed in both age groups by a reduction in the amplitude of characteristic waves in the early auditory evoked potential.

Graphical abstract Download full-size imageHighlights* Adults and infants show similar effects generated by unexpected word forms. * 14-Month-olds show an analogue of the adult PMN effect. * Infants detect mispronounced vowels from 225 ms, and larger changes 75 ms earlier. * Adult semantic N400 effects are discrete from expectation-related PMN effects. * Novel data visualisation method integrates spatial and temporal information.