Event-related potential indices of semantic priming following an unrelated intervening item

Interposing an unrelated word between related primes and targets often disrupts priming. This finding has been used to support the view that semantic information is represented in a distributed fashion, rather than locally. In some studies where unrelated items intervened between the prime and target, however, significant priming was nevertheless obtained. The discrepant results of these studies has been attributed to differences in speed-accuracy tradeoff, post-lexical checking, conscious rehearsal of the prime and differences in the depth to which the prime and target were processed. The present study was designed in such a way as to minimize variability associated with post-lexical influences. The N400 component of the human event-related potential was used as a physiological index of the extent to which priming occurred with and without the interposition of an unrelated item. Priming effects on both the amplitude and latency of the N400 were rendered non-significant by the presence of an intervening unrelated word. The results are interpreted as tentative evidence that semantic representations are distributed.