Interpreting dissociations between regular and irregular past-tense morphology: Evidence from event-related potentials

Abstract

Neuropsychological dissociations between regular and irregular English past-tense morphology have been reported using a lexical-decision task in which past-tense primes immediately precede present-tense targets. We present N400 event-related potential data from healthy participants using the same design. Both regular and irregular past-tense forms primed corresponding present-tense forms, but with a longer duration for irregular verbs. Phonological control conditions suggested that differences in formal overlap between prime and target contributes to, but does not account for this difference, suggesting a link between irregular morphology and semantics. Further analysis, dividing the irregular verbs into two categories (weak irregular and strong) revealed that priming for strong verbs was reliably stronger than that for weak irregular and regular verbs, which were statistically indistinguishable from one another. We argue that although we observe a regular-irregular dissociation, the nature of this dissociation is more consistent with single-than with dual-system models of inflectional morphology.

Graded Effects of Regularity in Language Revealed by N400 Indices of Morphological Priming

“…The results are similar to previous ERP studies in that we did find significant N400 priming effects for regular verbs (Rodriguez-Fornells et al, 2002;Münte et al, 1999;Weyerts et al, 1996). Likewise, consistent with a recent study by Justus et al (2008), we also found significant ERP priming for irregular verbs. Thus, the results illustrate the presence of morphological priming effects that are not uniquely related to rule-like forms.…”

“…This pattern of effects is compatible with the results of the auditory immediate priming study reported by Justus et al (2008). Their results showed stronger and more prolonged priming effects for strong (vowel-change) irregular verbs compared to weak irregulars and regulars.…”

“…The results suggested that the differences among forms can be attributed to the orthographic similarity of prime and target. Similarly, Justus et al (2008) found similar N400 priming effects for regulars and weak irregulars using auditory lexical decision and auditory primes. That said, the strongest priming was found for strong irregulars, compared to regulars and weak irregulars, which is the opposite of what we might have predicted given prior findings in visual lexical decision.…”

“…They are formally irregular because they do involve a somewhat unpredictable change to the stem; however, they also involve adding a regular-like suffix. The results of previous studies indicate that the brain responses for these verbs are more similar to regular than vowel-change irregular verbs ( Justus et al, 2008;Joanisse & Seidenberg, 2005). These forms are contrasted with "vowel-change" irregulars such as take-took, which do not take a regularlike ending, and are highly inconsistent.…”

An event-related potential study of cross-modal morphological and phonological priming

“…Event-related potentials were recorded from sixteen healthy participants who performed a lexical-decision task in which past-tense primes immediately preceded present-tense targets. To minimize intra-modal phonological priming effects, cross-modal presentation between auditory primes and visual targets was employed, and results were compared to a companion intra-modal auditory study (Justus, Larsen, de Mornay Davies, & Swick, 2008). For both regular and irregular verbs, faster response times and reduced N400 components were observed for present-tense forms when primed by the corresponding past-tense forms.…”