Effects of semantic matching and of semantic category on reaction time and N400 that resist numerous repetitions

Abstract

a b s t r a c tThe N400 event-related potential (ERP) is a brain response to any potentially meaningful stimulus. Like reaction time (RT), the amplitude of this ERP is reduced by the prior presentation of a semantically related stimulus. However, results of a few studies suggest that this semantic matching effect could be reduced when using already presented stimuli, and rapidly disappear with further presentations. On the other hand, the topography of the N400 on the scalp depends on the semantic category of the stimulus. Like the semantic matching effect, this category effect also seems to be smaller for already presented stimuli. Taken together, these facts suggest that the semantic processes indexed by the N400 could be absent for stimuli that have already been presented multiple times. Here, we show that this conclusion would be premature. We used the same semantic categorization task in conditions of massive repetition and in conditions of single presentation. We found that the effects of semantic matching and of semantic category on RTs and N400s were similar in the two conditions. Moreover, the localization of the sources of the independent components accounting for the match effect revealed brain regions that were common to both conditions. These results suggest that N400s and RTs could be used to study the semantic processes triggered by one content word.

From N400 to N300: Variations in the timing of semantic processing with repetition

“…However, more recent results suggest that 400 ms is not indicative of a minimal duration for the semantic processing reflected in N400 activity to occur and that this ERP component can also peak earlier. Using highly repeated words in semantic categorization tasks, Debruille and Renoult (2009) and Renoult and Debruille (2011) reported that the N400 could peak as early as 300 to 330 ms after word onset (see also Simon et al, 2004 for similar findings in a lexical decision task). These early N400s were shown to be sensitive to the same variables as the N400s obtained in non-repeated conditions.…”

“…These early N400s were shown to be sensitive to the same variables as the N400s obtained in non-repeated conditions. Namely, they were modulated by semantic priming (across SOAs), semantic category and concreteness and were not affected by physical matching (Debruille and Renoult, 2009;Renoult and Debruille, 2011;Renoult et al, 2010Renoult et al, , 2012. Despite the observation that these N400s peaked much earlier for highly repeated words than non-repeated words, it could be demonstrated that the onset of the deflections themselves was the same in both conditions (around 230 ms after word onset; Debruille and Renoult, 2009).…”

“…Namely, they were modulated by semantic priming (across SOAs), semantic category and concreteness and were not affected by physical matching (Debruille and Renoult, 2009;Renoult and Debruille, 2011;Renoult et al, 2010Renoult et al, , 2012. Despite the observation that these N400s peaked much earlier for highly repeated words than non-repeated words, it could be demonstrated that the onset of the deflections themselves was the same in both conditions (around 230 ms after word onset; Debruille and Renoult, 2009). This is concordant with numerous observations showing that the onset latency of the N400 does not vary much in the visual modality, starting 200 to 250 ms after word onset in various conditions (Deacon et al, 1995;Hagoort et al, 2004;Helenius et al, 1998;van Berkum et al, 1999).…”

“…Using the N400 as a measure of the duration of semantic processing, and not just as an index showing that this processing has taken place, is thus of special interest. N400 effects evoked by highly repeated words are thus characterized by a shorter duration (i.e., peak latency) but not an earlier onset (Debruille and Renoult, 2009). It might be concluded from these studies that the use of high rates of repetition results in a shortening of the duration of semantic processing.…”

“…First, these studies did not include analyses of individual levels of repetition. In Debruille and Renoult (2009), 30 presentations of the same words were compared to non-repeated conditions. This study thus does not clarify if N400 latency is stable across different repetition levels, or if massive repetition is necessary to shorten the duration of semantic processing.…”