Visual mismatch negativity elicited by semantic violations in visual words

Automatic Change Detection in Interwoven Sequences: A Visual Mismatch Negativity Study

In this study, we investigated whether the cognitive system, known to be able to register regular visual event sequences and the violation of these sequences automatically, had the capacity of processing two sequences simultaneously. To this end, we measured the visual mismatch negativity (vMMN) component of ERPs as interwoven event sequences simultaneously presented to the left and right side of the screen. One of the sequences consisted of geometric patterns (diamonds); the other, photographs of human faces. In successive cycles, parts of the stimuli vanished and then re-appeared (the OFF/ON method). The vanishing parts served as either standard (frequently vanishing parts) or infrequent (deviant) events, but these events were task-irrelevant. The 20 adult participants (age 21.40 ± 2.72 years) performed a visual tracking task, with the OFF/ON task being a passive oddball paradigm. According to the results, both OFF and ON events, and both diamond and face stimuli elicited the vMMN component, showing that the system underlying this activity is capable of processing two event sequences if the sequences consist of fairly different kind of objects as stimuli. The sLORETA analysis showed that the source of vMMN was more frequent contralaterally to the deviant event, and the sources comprised loci from ventral and dorsal structures, as well as some anterior loci.

Seeking the neural representation of statistical properties in print during implicit processing of visual words

Statistical learning (SL) plays a key role in literacy acquisition. Studies have increasingly revealed the influence of distributional statistical properties of words on visual word processing, including the effects of word frequency (lexical level) and mappings between orthography, phonology, and semantics (sub-lexical level). However, there has been scant evidence to directly confirm that the statistical properties contained in print can be directly characterized by neural activities. Using time-resolved representational similarity analysis (RSA), the present study examined neural representations of different types of statistical properties in visual word processing. From the perspective of predictive coding, an equal probability sequence with low built-in prediction precision and three oddball sequences with high built-in prediction precision were designed with consistent and three types of inconsistent (orthographically inconsistent, orthography-to-phonology inconsistent, and orthography-to-semantics inconsistent) Chinese characters as visual stimuli. In the three oddball sequences, consistent characters were set as the standard stimuli (probability of occurrence p = 0.75) and three types of inconsistent characters were set as deviant stimuli (p = 0.25), respectively. In the equal probability sequence, the same consistent and inconsistent characters were presented randomly with identical occurrence probability (p = 0.25). Significant neural representation activities of word frequency were observed in the equal probability sequence. By contrast, neural representations of sub-lexical statistics only emerged in oddball sequences where short-term predictions were shaped. These findings reveal that the statistical properties learned from long-term print environment continues to play a role in current word processing mechanisms and these mechanisms can be modulated by short-term predictions.

Neural Mechanisms of Subliminal Mentor-Student Relationship Stimuli Processing: An ERP Study

In educational contexts, mentorship roles often complicate the mentor-student relationship because mentors act not only as the closest academic ally of graduate students but also their program supervisors who can affect their timely graduation. This study examines how graduate students react to their mentors’ names when subliminally presented. A total of 63 graduate students (31 male; Mean Age = 23.450) were asked to perform an irrelevant color judgment task of valenced words (positive vs. negative relationship words) after a subliminal presentation of three different types of names (i.e., mentors, authorities, and friends). Results show that mentor and friend names elicit a greater P2 peak than authority names, whereas mentor names evoke a reduced N2 and P3 amplitude than friend and authority names. In addition, participants with a history of abusive supervision tend to have an overall decline in P2 amplitude. These event-related potential (ERP) findings suggest that mentors are perceived by students as familiar while attention-inducing figures.

Unified Coding of Spectral and Temporal Phonetic Cues: Electrophysiological Evidence for Abstract Phonological Features

Spoken word recognition models and phonological theory propose that abstract features play a central role in speech processing. It remains unknown, however, whether auditory cortex encodes linguistic features in a manner beyond the phonetic properties of the speech sounds themselves. We took advantage of the fact that English phonology functionally codes stops and fricatives as voiced or voiceless with two distinct phonetic cues: Fricatives use a spectral cue, whereas stops use a temporal cue. Evidence that these cues can be grouped together would indicate the disjunctive coding of distinct phonetic cues into a functionally defined abstract phonological feature. In English, the voicing feature, which distinguishes the consonants [s] and [t] from [z] and [d], respectively, is hypothesized to be specified only for voiceless consonants (e.g., [s t]). Here, participants listened to syllables in a many-to-one oddball design, while their EEG was recorded. In one block, both voiceless stops and fricatives were the standards. In the other block, both voiced stops and fricatives were the standards. A critical design element was the presence of intercategory variation within the standards. Therefore, a many-to-one relationship, which is necessary to elicit an MMN, existed only if the stop and fricative standards were grouped together. In addition to the ERPs, event-related spectral power was also analyzed. Results showed an MMN effect in the voiceless standards block—an asymmetric MMN—in a time window consistent with processing in auditory cortex, as well as increased prestimulus beta-band oscillatory power to voiceless standards. These findings suggest that (i) there is an auditory memory trace of the standards based on the shared (voiceless) feature, which is only functionally defined; (ii) voiced consonants are underspecified; and (iii) features can serve as a basis for predictive processing. Taken together, these results point toward auditory cortex's ability to functionally code distinct phonetic cues together and suggest that abstract features can be used to parse the continuous acoustic signal.

Lexical processing in sign language: A visual mismatch negativity study

Event-related potential studies of spoken and written language show the automatic access of auditory and visual words, as indexed by mismatch negativity (MMN) or visual MMN (vMMN). The present study examined whether the same automatic lexical processing occurs in a visual-gestural language, i.e., Hong Kong Sign Language (HKSL). Using a classic visual oddball paradigm, deaf signers and hearing non-signers were presented with a sequence of static images representing HKSL lexical signs and non-signs. When compared with hearing non-signers, deaf signers exhibited an enhanced vMMN elicited by the lexical signs at around 230 ms, and a larger P1-N170 complex evoked by both lexical sign and non-sign standards at the parieto-occipital area in the early time window between 65 ms and 170 ms. These findings indicate that deaf signers implicitly process the lexical sign and that neural response differences between deaf signers and hearing non-signers occur at the early stage of sign processing.