Reinstatement of memory-related neural activity measured with high temporal precision potentially provides a useful index for real-time monitoring of the timing of activation of memory content during cognitive processing. The utility of such an index extends to any situation where one is interested in the (relative) timing of activation of different sources of information in memory, a paradigm case of which is tracking lexical activation during language processing. Essential for this approach is that memory reinstatement effects are robust, so that their absence (in the average) definitively indicates that no lexical activation is present. We used electroencephalography to test the robustness of a reported subsequent memory finding involving reinstatement of frequency-specific entrained oscillatory brain activity during subsequent recognition. Participants learned lists of words presented on a background flickering at either 6 or 15 Hz to entrain a steady-state brain response. Target words subsequently presented on a non-flickering background that were correctly identified as previously seen exhibited reinstatement effects at both entrainment frequencies. Reliability of these statistical inferences was however critically dependent on the approach used for multiple comparisons correction. We conclude that effects are not robust enough to be used as a reliable index of lexical activation during language processing.
MULTIFILE
Gamma-band neuronal synchronization during sentence-level language comprehension has previously been linked with semantic unification. Here, we attempt to further narrow down the functional significance of gamma during language comprehension, by distinguishing between two aspects of semantic unification: successful integration of word meaning into the sentence context, and prediction of upcoming words. We computed eventrelated potentials (ERPs) and frequency band-specific electroencephalographic (EEG) power changes while participants read sentences that contained a critical word (CW) that was (1) both semantically congruent and predictable (high cloze, HC), (2) semantically congruent but unpredictable (low cloze, LC), or (3) semantically incongruent (and therefore also unpredictable; semantic violation, SV). The ERP analysis showed the expected parametric N400 modulation (HC < LC < SV). The time-frequency analysis showed qualitatively different results. In the gamma-frequency range, we observed a power increase in response to the CW in the HC condition, but not in the LC and the SV conditions. Additionally, in the theta frequency range we observed a power increase in the SV condition only. Our data provide evidence that gamma power increases are related to the predictability of an upcoming word based on the preceding sentence context, rather than to the integration of the incoming word's semantics into the preceding context. Further, our theta band data are compatible with the notion that theta band synchronization in sentence comprehension might be related to the detection of an error in the language input.
MULTIFILE
Posterpresentatie op conferentie Introductie: De afgelopen twee decennia is er geen communis opinio over de vraag of er sprake is van regionale factoren bij de constituentvolgorde in de Nederlandse Gebarentaal (NGT) (Coerts, 1994; Crasborn & De Wit, 2005; Vermeerbergen, Nijen Twilhaar & Van Herreweghe, 2013). Dit onderzoek levert een bijdrage aan de discussie over constituent-volgorde in het algemeen, doordat werd onderzocht of constituentvolgorde in NGT verschillend is voor eerste- en tweedetaalverwervers van de NGT. Methode: Er namen tien participanten (studenten NGT aan de Hogeschool Utrecht) deel: vijf dove moedertaalgebruikers en vijf horende studenten (leeftijd 19-30 jaar). Productie werd uitgelokt van drie verschillende typen enkelvoudige zinnen aan de hand van plaatjes (Volterra et al., 1984): 6 zinnen met omkeerbare constituenten, 6 zinnen met niet-omkeerbare constituenten en 6 locatieve zinnen. Alle 180 geproduceerde zinnen werden getranscribeerd en syntactisch (Subject, Object, Verbum) geanalyseerd. Resultaten: De moedertaalgebruikers gaven duidelijk de voorkeur aan de volgorde SVO of SVOV bij omkeerbare zinnen en SOV voor niet-omkeerbare zinnen. Voor de locatieve zinnen werd veel variatie gevonden, met een lichte voorkeur voor OSV. De T2-verwervers vertoonden veel variatie in de productie van omkeerbare zinnen zonder duidelijk patroon. Voor de niet-omkeerbare zinnen werd een lichte voorkeur voor SOV gevonden en wederom variatie. De loca-tieve zinnen werden voornamelijk uitgedrukt in de volgorde OSV. Conclusie: Deze studie toont aan dat de constituentvolgorde van moedertaalgebruikers en T2-verwervers verschillen. Opvallend is dat de T2-verwervers de neiging hebben de regel voor locatieve zinnen ‘Het grootste element voorop in de zin’ te overgeneraliseren naar het type niet-omkeerbare zin.
MULTIFILE