This study investigated the influence of first language (L1) phoneme features and phonetic salience on discrimination of second language (L2) American English (AE) vowels. On a perceptual task, L2 adult learners of English with Spanish, Japanese or Russian as an L1 showed poorer discrimination of the spectral-only difference between /æ:/ as the oddball (deviant) among frequent /ɑ:/ stimuli compared to AE controls. The Spanish listeners showed a significant difference from the controls for the spectral-temporal contrast between /ɑ:/ and /ʌ/ for both perception and the neural Mismatch Negativity (MMN), but only for deviant /ɑ:/ versus /ʌ/ (duration decrement). For deviant /ʌ/ versus /ɑ:/, and for deviant /æ:/ versus /ʌ/ or /ɑ:/, all participants showed equivalent MMN amplitude. The asymmetrical pattern for /ɑ:/ and /ʌ/ suggested that L2 phonetic detail was maintained only for the deviant. These findings indicated that discrimination was more strongly influenced by L1 phonology than phonetic salience.

This study examined behavioral and neurophysiological indices of discrimination of an English vowel contrast [ɪ–ɛ] by early and late bilingual Spanish–English speakers, compared to monolingual English speakers. Electrophysiological measures (Mismatched Negativity – MMN) and behavioral measures (AX discrimination and forced-choice identification) were employed to examine perception of a nine-step vowel continuum, re-synthesized from natural tokens. Results revealed that (i) both monolingual and early bilinguals showed similar behavioral perception while late bilinguals performed more poorly on all behavioral tasks; and (ii) monolinguals showed robust evidence of discrimination (MMN) at a pre-attentive level that was significantly larger than found for either early or late bilinguals. These findings suggested that early input of English vowels to bilinguals did not necessarily lead to robust, automatic processing, as measured at a more attention-independent neural level; but earlier experience with a second language allowed for native-like speech perception measured with behavioral tasks.

Survivors of severe traumatic brain injury (TBI) often demonstrate impairments in the cognitive control functions of detecting response conflict and signaling for recruitment of cognitive resources to appropriately adjust performance. These cognitive control functions can be measured using conflict adaptation effects, wherein manifestations of conflict detection and processing are reduced following high- relative to low-conflict trials. Event-related potentials (ERPs) were collected while 18 survivors of severe traumatic brain injury (TBI) and 21 demographically matched control participants performed a modified Stroop task. The incongruent-minus-congruent trial Stroop effect for trials preceded by incongruent (high conflict) and congruent (low conflict) trials were compared for behavioral (response time [RT] and error rate) and ERP reflections of cognitive control. Behavioral data showed a reduction in the Stroop effect for both control and TBI participant RTs when preceded by incongruent trials. The magnitude of these effects did not differentiate control and TBI participants. ERP data revealed a centro-parietal conflict slow potential (conflict SP) that differentiated incongruent from congruent trials. Planned comparisons showed a decreased amplitude conflict SP when ERPs were preceded by incongruent trials in control, but not TBI participants. Results indicate subtle TBI-related impairments in conflict resolution mechanisms in the context of intact RT-related conflict adaptation. (JINS, 2009, 15, 927–937.)

In the present study we evaluated the relationships between the P300 event-related potential and event-related desynchronization (ERD) of electroencephalographic alpha activity by simultaneously analyzing P300 as well as 7–10- and 10–14-Hz alpha ERD responses from auditory passive and active oddball conditions. We compared the effects of task (target vs. nontarget) and electrode (Fz, Cz, Pz) on P300 and ERD, and correlated P300 amplitude/latency with ERD maximal amplitude/latency across individuals. The major findings were that P300 as well as slow and fast alpha ERD manifested similar task and electrode effects. P300 preceded ERD and predicted individual variance of both slow and fast alpha ERD. The relationships of P300 with alpha ERD were different for the slow and fast alpha frequencies. These findings indicate that P300 and ERD are related such that slow and fast alpha ERDs are specifically guided or modified by the internal event(s) indexed by P300.