Faces with foreign accents: An event-related potential study of accented sentence comprehension.

Mounting Event-Related Potential (ERP) research testing the neurocognitive processes of foreign- and native-accented speech comprehension shows that listeners process foreign-accented speech in qualitatively and quantitatively different ways from native-accented speech. Previous ERP research has presented listeners with foreign- and native-accented sentences only, devoid of any cues to the speaker's identity. Additional cues about the foreign-accented speaker identity, such as faces, may be useful in aiding listeners' processing, potentially reducing differences between neurocognitive processes associated with foreign-accented and native-accented speech comprehension. This study tested whether providing listeners with extra-linguistic face cues to the speakers' identity affects the ERP correlates of grammatical and semantic processing of foreign-accented and native-accented sentences. Specifically, we presented listeners with face cues to speaker identity followed by native- and foreign-accented sentences that were identical to Grey and Van Hell (2017), who did not provide face cues. To elucidate the effects of face cues, we compared the present study's Face Cue data with the Grey and Van Hell (2017) No Face Cue data. For grammar processing, the results showed a biphasic Nref-P600 for native-accented speech and a P600 for foreign-accented speech in the Face Cue group. In the No Face Cue group, results for grammar processing showed an Nref for native-accented speech and no significant ERP effects for foreign-accented speech. This result indicates that face cues were effective in aiding processing of foreign-accented sentences. For semantic processing, there were robust N400 effects for native-accented speech and delayed N400s for foreign-accented speech in the Face Cue and No Face Cue groups. This pattern indicates that the extra-linguistic face cue to foreign-accented speaker identity did not affect semantic processing. Overall, the results provide neurocognitive evidence that the integration of speaker and face information aids listeners during the processing of foreign-accented speech, particularly for grammatical processing.

How right is left? Handedness modulates neural responses during morphosyntactic processing.

Most neurocognitive models of language processing generally assume population-wide homogeneity in the neural mechanisms used during language comprehension, yet individual differences are known to influence these neural mechanisms. In this study, we focus on handedness as an individual difference hypothesized to affect language comprehension. Left-handers and right-handers with a left-handed blood relative, or familial sinistrals, are hypothesized to process language differently than right-handers with no left-handed relatives (Hancock and Bever, 2013; Ullman, 2004). Yet, left-handers are often excluded from neurocognitive language research, and familial sinistrality in right-handers is often not taken into account. In the current study we used event-related potentials to test morphosyntactic processing in three groups that differed in their handedness profiles: left-handers (LH), right-handers with a left-handed blood relative (RH FS+), and right-handers with no reported left-handed blood relative (RH FS-; both right-handed groups were previously tested by Tanner and Van Hell, 2014). Results indicated that the RH FS- group showed only P600 responses during morphosyntactic processing whereas the LH and RH FS+ groups showed biphasic N400-P600 patterns. N400s in LH and RH FS+ groups are consistent with theories that associate left-handedness (self or familial) with increased reliance on lexical/semantic mechanisms during language processing. Inspection of individual-level results illustrated that variability in RH FS- individuals' morphosyntactic processing was remarkably low: most individuals were P600-dominant. In contrast, LH and RH FS+ individuals showed marked variability in brain responses, which was similar for both groups: half of individuals were N400-dominant and half were P600-dominant. Our findings have implications for neurocognitive models of language that have been largely formulated around data from only right-handers without accounting for familial sinistrality or including left-handers, and moreover highlight that there is systematic - and often ignored - variability in language processing outcomes in neurologically healthy populations.

Dissociating retrieval interference and reanalysis in the P600 during sentence comprehension.

We investigated the relative independence of two key processes in language comprehension, as reflected in the P600 ERP component. Numerous studies have linked the P600 to sentence- or message-level reanalysis; however, much research has shown that skilled, cue-based memory retrieval operations are also important to successful language processing. Our goal was to identify whether these cue-based retrieval operations are part of the reanalysis processes indexed by the P600. To this end, participants read sentences that were either grammatical or ungrammatical via subject-verb agreement violations, and in which there was either no possibility for retrieval interference or there was an attractor noun interfering with the computation of subject-verb agreement (e.g., "The slogan on the political poster(s) was/were …"). A stimulus onset asynchrony manipulation (fast, medium, or slow presentation rate) was designed to modulate participants' ability to engage in reanalysis processes. Results showed a reliable attraction interference effect, indexed by reduced behavioral sensitivity to ungrammaticalities and P600 amplitudes when there was an opportunity for retrieval interference, as well as an effect of presentation rate, with reduced behavioral sensitivity and smaller P600 effects at faster presentation rates. Importantly, there was no interaction between the two, suggesting that retrieval interference and sentence-level reanalysis processes indexed by the P600 can be neurocognitively distinct processes.

Second language processing shows increased native-like neural responses after months of no exposure.

Although learning a second language (L2) as an adult is notoriously difficult, research has shown that adults can indeed attain native language-like brain processing and high proficiency levels. However, it is important to then retain what has been attained, even in the absence of continued exposure to the L2--particularly since periods of minimal or no L2 exposure are common. This event-related potential (ERP) study of an artificial language tested performance and neural processing following a substantial period of no exposure. Adults learned to speak and comprehend the artificial language to high proficiency with either explicit, classroom-like, or implicit, immersion-like training, and then underwent several months of no exposure to the language. Surprisingly, proficiency did not decrease during this delay. Instead, it remained unchanged, and there was an increase in native-like neural processing of syntax, as evidenced by several ERP changes--including earlier, more reliable, and more left-lateralized anterior negativities, and more robust P600s, in response to word-order violations. Moreover, both the explicitly and implicitly trained groups showed increased native-like ERP patterns over the delay, indicating that such changes can hold independently of L2 training type. The results demonstrate that substantial periods with no L2 exposure are not necessarily detrimental. Rather, benefits may ensue from such periods of time even when there is no L2 exposure. Interestingly, both before and after the delay the implicitly trained group showed more native-like processing than the explicitly trained group, indicating that type of training also affects the attainment of native-like processing in the brain. Overall, the findings may be largely explained by a combination of forgetting and consolidation in declarative and procedural memory, on which L2 grammar learning appears to depend. The study has a range of implications, and suggests a research program with potentially important consequences for second language acquisition and related fields.