From sublexical facilitation to lexical competition: ERP effects of masked neighbor priming

Interactive-activation models posit that visual word recognition involves co-activation of orthographic neighbors (e.g., note, node) and competition among them via lateral inhibitory connections. Behavioral evidence of this lexical competition comes from masked priming paradigms, in which target words elicit slower responses when preceded by a neighbor (e.g., note-NODE) than when preceded by an unrelated word (e.g., kiss-NODE). In the present study, we used ERPs to investigate how masked high frequency word primes influence processing of low frequency word and pseudoword targets. Word targets preceded by a neighbor prime elicited larger negativities within the N400 window than those preceded by an unrelated prime across bilateral anterior sites, which we call a reversed N400 priming effect. Consistent with the behavioral literature, the size of the reversed N400 priming effect was larger for targets from high-density orthographic neighborhoods and for participants who scored higher on a behavioral measure of spelling recognition. Indeed, the opposite effect (i.e., smaller negativities within the N400 window for word targets preceded by a neighbor) was observed for words from low-density orthographic neighborhoods and for less-skilled spellers. Traditional priming was also observed within the N250 window for word targets and within both the N250 or N400 windows for pseudoword targets. The specificity of the reversed N400 priming effect to situations in which both words have precise lexical representations suggests that it, like the behavioral interference effect, indexes lexical competition during visual word recognition.

Interactions in the neighborhood: Effects of orthographic and phonological neighbors on N400 amplitude

The present study investigated effects of phonological and orthographic neighborhood density on event-related potentials, with an aim to better specify the factors that determine N400 amplitude in single word reading paradigms. We orthogonally manipulated the number of orthographic and phonological neighbors of words using the Levenshtein Distance metric (OLD20 and PLD20, respectively). The results showed opposite effects of phonological neighborhood density (PND) as a function of orthographic neighborhood density (OND). Larger N400 amplitudes were elicited by words with high PND compared with low PND when OND was high, and smaller N400 amplitudes were observed with high PND compared with low PND words when OND was low. We interpret these findings using the notion of cross-code consistency, according to which the compatibility of orthographic and phonological representations activated by a given word influences the process of recognizing that word. Words with similar numbers of orthographic and phonological neighbors have more consistent spellings and pronunciations across the neighborhood, and generate larger N400 amplitudes.

Early MEG markers for reading Chinese phonograms: evidence from radical combinability and consistency effects

Studies using functional magnetic resonance imaging have indicated that activities in the left inferior frontal cortex and left temporoparietal regions are associated with orthographic neighborhood size. To elucidate the temporal dynamics of reading-related cortical activities, we manipulated two types of neighborhood properties for Chinese phonograms, phonetic combinability and consistency. By using source analysis techniques in combination with magnetoencephalography, the results demonstrated a combinability effect in the right fusiform gyrus at ∼ 170 ms, which may reflect perceptual expertise in processing Chinese orthography. During 200 ms to 250 ms, the left anterior insula showed larger activity in reading small combinability characters than in reading large combinability characters, and the left inferior parietal cortex showed greater activity in reading low consistency characters than in reading high consistency characters. These results indicate that the left anterior insula cortex and left inferior parietal cortex may play important roles in the early stages of reading Chinese phonograms.