Unique N170 signatures to words and faces in deaf ASL signers reflect experience-specific adaptations during early visual processing

Asymetric Event-Related Potential Priming Effects Between English Letters and American Sign Language Fingerspelling Fonts

Letter recognition plays an important role in reading and follows different phases of processing, from early visual feature detection to the access of abstract letter representations. Deaf ASL-English bilinguals experience orthography in two forms: English letters and fingerspelling. However, the neurobiological nature of fingerspelling representations, and the relationship between the two orthographies, remains unexplored. We examined the temporal dynamics of single English letter and ASL fingerspelling font processing in an unmasked priming paradigm with centrally presented targets for 200 ms preceded by 100 ms primes. Event-related brain potentials were recorded while participants performed a probe detection task. Experiment 1 examined English letter-to-letter priming in deaf signers and hearing non-signers. We found that English letter recognition is similar for deaf and hearing readers, extending previous findings with hearing readers to unmasked presentations. Experiment 2 examined priming effects between English letters and ASL fingerspelling fonts in deaf signers only. We found that fingerspelling fonts primed both fingerspelling fonts and English letters, but English letters did not prime fingerspelling fonts, indicating a priming asymmetry between letters and fingerspelling fonts. We also found an N400-like priming effect when the primes were fingerspelling fonts which might reflect strategic access to the lexical names of letters. The studies suggest that deaf ASL-English bilinguals process English letters and ASL fingerspelling differently and that the two systems may have distinct neural representations. However, the fact that fingerspelling fonts can prime English letters suggests that the two orthographies may share abstract representations to some extent.

Fingerspelling and Its Role in Translanguaging

Fingerspelling is a critical component of many sign languages. This manual representation of orthographic code is one key way in which signers engage in translanguaging, drawing from all of their linguistic and semiotic resources to support communication. Translanguaging in bimodal bilinguals is unique because it involves drawing from languages in different modalities, namely a signed language like American Sign Language and a spoken language like English (or its written form). Fingerspelling can be seen as a unique product of the unified linguistic system that translanguaging theories purport, as it blends features of both sign and print. The goals of this paper are twofold: to integrate existing research on fingerspelling in order to characterize it as a cognitive-linguistic phenomenon and to discuss the role of fingerspelling in translanguaging and communication. We will first review and synthesize research from linguistics and cognitive neuroscience to summarize our current understanding of fingerspelling, its production, comprehension, and acquisition. We will then discuss how fingerspelling relates to translanguaging theories and how it can be incorporated into translanguaging practices to support literacy and other communication goals.

Ongoing Sign Processing Facilitates Written Word Recognition in Deaf Native Signing Children

Signed and written languages are intimately related in proficient signing readers. Here, we tested whether deaf native signing beginning readers are able to make rapid use of ongoing sign language to facilitate recognition of written words. Deaf native signing children (mean 10 years, 7 months) received prime target pairs with sign word onsets as primes and written words as targets. In a control group of hearing children (matched in their reading abilities to the deaf children, mean 8 years, 8 months), spoken word onsets were instead used as primes. Targets (written German words) either were completions of the German signs or of the spoken word onsets. Task of the participants was to decide whether the target word was a possible German word. Sign onsets facilitated processing of written targets in deaf children similarly to spoken word onsets facilitating processing of written targets in hearing children. In both groups, priming elicited similar effects in the simultaneously recorded event related potentials (ERPs), starting as early as 200 ms after the onset of the written target. These results suggest that beginning readers can use ongoing lexical processing in their native language - be it signed or spoken - to facilitate written word recognition. We conclude that intimate interactions between sign and written language might in turn facilitate reading acquisition in deaf beginning readers.

Working Memory for Faces among Individuals with Congenital Deafness

BACKGROUND

 Studies examining face processing among individuals with congenital deafness show inconsistent results that are often accounted for by sign language skill. However, working memory for faces as an aspect of face processing has not yet been examined in congenital deafness.

PURPOSE

 To explore working memory for faces among individuals with congenital deafness who are skilled in sign language.

RESEARCH DESIGN

 A quasi-experimental study of individuals with congenital deafness and a control group.

STUDY SAMPLE

 Sixteen individuals with congenital deafness who are skilled in sign language and 18 participants with intact hearing, matched for age, and education.

INTERVENTION

 The participants performed two conditions of the N-back test in ascending difficulty (i.e., 1-back and 2-back).

DATA COLLECTION AND ANALYSIS

 Levene's and Shapiro-Wilk tests were used to assess group homoscedasticity and normality, respectively. A two-way repeated measures analysis of variance was applied to compare the groups in response time and accuracy of the N-back test, as well as Pearson correlation between response time and accuracy, and sign language skill duration.

RESULTS

 The congenital deafness group performed better than controls, as was found in the response time but not in the accuracy variables. However, an interaction effect showed that this pattern was significant for the 1-back but not for the 2-back condition in the response time but not the accuracy. Further, there was a marginal effect in response time but a significant one in accuracy showing the 2-back was performed worse than the 1-back. No significant correlation was found between response time and accuracy, and sign language skill duration.

CONCLUSION

 Face processing advantage associated with congenital deafness is dependent on cognitive load, but sign language duration does not affect this trend. In addition, response time and accuracy are not equally sensitive to performance differences in the N-back test.

Masked ERP repetition priming in deaf and hearing readers

Deaf readers provide unique insights into how the reading circuit is modified by altered linguistic and sensory input. We investigated whether reading-matched deaf and hearing readers (n = 62) exhibit different ERP effects associated with orthographic to phonological mapping (N250) or lexico-semantic processes (N400). In a visual masked priming paradigm, participants performed a go/no-go categorization task; target words were preceded by repeated or unrelated primes. Prime duration and word frequency were manipulated. Hearing readers exhibited typical N250 and N400 priming effects with 50 ms primes (greater negativity for unrelated primes) and smaller effects with 100 ms primes. Deaf readers showed a surprising reversed priming effect with 50 ms primes (greater negativity for related primes), and more typical N250 and N400 effects with 100 ms primes. Correlation results suggested deaf readers with poorer phonological skills drove this effect. We suggest that weak phonological activation may create orthographic "repetition enhancement" or form/lexical competition in deaf readers.

The neurocognitive basis of skilled reading in prelingually and profoundly deaf adults

Deaf individuals have unique sensory and linguistic experiences that influence how they read and become skilled readers. This review presents our current understanding of the neurocognitive underpinnings of reading skill in deaf adults. Key behavioural and neuroimaging studies are integrated to build a profile of skilled adult deaf readers and to examine how changes in visual attention and reduced access to auditory input and phonology shape how they read both words and sentences. Crucially, the behaviours, processes, and neural circuity of deaf readers are compared to those of hearing readers with similar reading ability to help identify alternative pathways to reading success. Overall, sensitivity to orthographic and semantic information is comparable for skilled deaf and hearing readers, but deaf readers rely less on phonology and show greater engagement of the right hemisphere in visual word processing. During sentence reading, deaf readers process visual word forms more efficiently and may have a greater reliance on and altered connectivity to semantic information compared to their hearing peers. These findings highlight the plasticity of the reading system and point to alternative pathways to reading success.