Phonological-Lexical Feedback during Early Abstract Encoding: The Case of Deaf Readers

Do age and language impairment affect speed of recognition for words with high and low closeness centrality within the phonological network?

PURPOSE

Speed and accuracy of lexical access change with healthy ageing and neurodegeneration. While a word's immediate phonological neighbourhood density (i.e. words differing by a single phoneme) influences access, connectivity to all words in the phonological network (i.e. closeness centrality) may influence processing. This study aimed to investigate the effect of closeness centrality on speed and accuracy of lexical processing pre- and post- a single word-training session in healthy younger and older adults, and adults with logopenic primary progressive aphasia (lvPPA), which affects phonological processing.

METHOD

Participants included 29 young and 17 older healthy controls, and 10 adults with lvPPA. Participants received one session of word-training on words with high or low closeness centrality, using a picture-word verification task. Changes in lexical decision reaction times (RT) and accuracy were measured.

RESULT

Baseline RT was unaffected by age and accuracy was at ceiling for controls. Post-training, only young adults' RT were significantly faster. Adults with lvPPA were slower and less accurate than controls at baseline, with no training effect. Closeness centrality did not influence performance.

CONCLUSION

Absence of training effect for older adults suggests higher threshold to induce priming, possibly associated with insufficient dosage or fatigue. Implications for word-finding interventions with older adults are discussed.

Perceptual Contiguity Does Not Modulate Matched-Case Identity-Priming Effects in Lexical Decision

In recent studies with the masked priming lexical decision task, matched-case identity-priming effects occur for nonwords but not for words (e.g., nonwords: ERTAR-ERTAR faster than ertar-ERTAR; words: ALTAR-ALTAR produces similar response times as altar-ALTAR). This dissociation is thought to result from lexical feedback influencing orthographic representations in word processing. As nonwords do not receive this feedback, bottom-up processing of prime-target integration leads to matched-case effects. However, the underlying mechanism of this effect in nonwords remains unclear. In this study, we added a color congruency manipulation across the prime and target in the matched-case identity-priming design. We aimed to determine whether the case effects originate at the early stages of prime-target perceptual integration or due to bottom-up activation of case-specific letter detectors. Results replicated the previous dissociation between words and nonwords regarding the matched-case identity effect. Additionally, we did not find any modulation of these effects by prime-target color congruency. These findings suggest that the locus of the matched-case identity effect is at an orthographic level of representation that encodes case information.

Lexical Competition Without Phonology: Masked Orthographic Neighbor Priming With Deaf Readers

Skilled reading is thought to rely on well-specified lexical representations that compete during visual word recognition. The establishment of these lexical representations is assumed to be driven by phonology. To test the role of phonology, we examined the prime lexicality effect (PLE), the index of lexical competition in signing deaf (N = 28) and hearing (N = 28) adult readers of Hungarian matched in age and education. We found no PLE for deaf readers even when reading skills were controlled for. Surprisingly, the hearing controls also showed reduced PLE; however, the effect was modulated by reading skill. More skilled hearing readers showed PLE, while more skilled deaf readers did not. These results suggest that phonology contributes to lexical competition; however, high-quality lexical representations are not necessarily built through phonology in deaf readers.

Are brand names special words? Letter visual-similarity affects the identification of brand names, but not common words

Brand names are often considered a special type of words of special relevance to examine the role of visual codes during reading: unlike common words, brand names are typically presented with the same letter‐case configuration (e.g., IKEA, adidas). Recently, Pathak et al. (European Journal of Marketing, 2019, 53, 2109) found an effect of visual similarity for misspelled brand names when the participants had to decide whether the brand name was spelled correctly or not (e.g., tacebook [baseword: facebook] was responded more slowly and less accurately than xacebook). This finding is at odds with both orthographically based visual‐word recognition models and prior experiments using misspelled common words (e.g., viotin [baseword: violin] is identified as fast as viocin). To solve this puzzle, we designed two experiments in which the participants had to decide whether the presented item was written correctly. In Experiment 1, following a procedure similar to Pathak et al. (European Journal of Marketing, 2019, 53, 2109), we examined the effect of visual similarity on misspelled brand names with/without graphical information (e.g., anazon vs. atazon [baseword: amazon]). Experiment 2 was parallel to Experiment 1, but we focused on misspelled common words (e.g., anarillo vs. atarillo; baseword: amarillo [yellow in Spanish]). Results showed a sizeable effect of visual similarity on misspelled brand names – regardless of their graphical information, but not on misspelled common words. These findings suggest that visual codes play a greater role when identifying brand names than common words. We examined how models of visual‐word recognition can account for this dissociation.

The impact of visual cues during visual word recognition in deaf readers: An ERP study

Although evidence is still scarce, recent research suggests key differences in how deaf and hearing readers use visual information during visual word recognition. Here we compared the time course of lexical access in deaf and hearing readers of similar reading ability. We also investigated whether one visual property of words, the outline-shape, modulates visual word recognition differently in both groups. We recorded the EEG signal of twenty deaf and twenty hearing readers while they performed a lexical decision task. In addition to the effect of lexicality, we assessed the impact of outline-shape by contrasting responses to pseudowords with an outline-shape that was consistent (e.g., mofor) or inconsistent (e.g., mosor) with their baseword (motor). Despite hearing readers having higher phonological abilities, results showed a remarkably similar time course of the lexicality effect in deaf and hearing readers. We also found that only for deaf readers, inconsistent-shape pseudowords (e.g., mosor) elicited larger amplitude ERPs than consistent-shape pseudowords (e.g., mofor) from 150 ms after stimulus onset and extending into the N400 time window. This latter finding supports the view that deaf readers rely more on visual characteristics than typical hearing readers during visual word recognition. Altogether, our results suggest different mechanisms underlying effective word recognition in deaf and hearing readers.

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.

An ERP investigation of orthographic precision in deaf and hearing readers

Phonology is often assumed to play a role in the tuning of orthographic representations, but it is unknown whether deaf readers' reduced access to spoken phonology reduces orthographic precision. To index how precisely deaf and hearing readers encode orthographic information, we used a masked transposed-letter (TL) priming paradigm. Word targets were preceded by TL primes formed by reversing two letters in the word and substitution primes in which the same two letters were replaced. The two letters that were manipulated were either in adjacent or non-adjacent positions, yielding four prime conditions: adjacent TL (e.g., chikcen-CHICKEN), adjacent substitution (e.g., chidven- CHICKEN), non-adjacent TL (e.g., ckichen-CHICKEN), and non-adjacent substitution (e.g., cticfen-CHICKEN). Replicating the standard TL priming effects, targets preceded by TL primes elicited smaller amplitude negativities and faster responses than those preceded by substitution primes overall. This indicates some degree of flexibility in the associations between letters and their positions within words. More flexible (i.e., less precise) representations are thought to be more susceptible to activation by TL primes, resulting in larger TL priming effects. However, the size of the TL priming effects was virtually identical between groups. Moreover, the ERP effects were shifted in time such that the adjacent TL priming effect arose earlier than the non-adjacent TL priming effect in both groups. These results suggest that phonological tuning is not required to represent orthographic information in a precise manner.

Deaf readers benefit from lexical feedback during orthographic processing

It has been proposed that poor reading abilities in deaf readers might be related to weak connections between the orthographic and lexical-semantic levels of processing. Here we used event related potentials (ERPs), known for their excellent time resolution, to examine whether lexical feedback modulates early orthographic processing. Twenty congenitally deaf readers made lexical decisions to target words and pseudowords. Each of those target stimuli could be preceded by a briefly presented matched-case or mismatched-case identity prime (e.g., ALTAR-ALTAR vs. altar- ALTAR). Results showed an early effect of case overlap at the N/P150 for all targets. Critically, this effect disappeared for words but not for pseudowords, at the N250—an ERP component sensitive to orthographic processing. This dissociation in the effect of case for word and pseudowords targets provides strong evidence of early automatic lexical-semantic feedback modulating orthographic processing in deaf readers. Interestingly, despite the dissociation found in the ERP data, behavioural responses to words still benefited from the physical overlap between prime and target, particularly in less skilled readers and those with less experience with words. Overall, our results support the idea that skilled deaf readers have a stronger connection between the orthographic and the lexical-semantic levels of processing.

ERP effects of masked orthographic neighbour priming in deaf readers

In masked priming studies with hearing readers, neighbouring words (e.g., wine, vine) compete through lateral inhibition. Here, we asked whether lateral inhibition also characterizes visual word recognition in deaf readers and whether the neural signature of this competition is the same as for hearing readers. Only real words have lexical representations that engage in lateral inhibition. Therefore, we compared processing of target words following neighbouring prime words (e.g., wine-VINE) and pseudowords (e.g., bine-VINE). Targets following words elicited larger amplitude N400s and slower lexical decision responses than those following pseudowords, indicating more effortful processing due to lateral inhibition. Although these effects went in the same direction for hearing and deaf readers, the distribution of the N400 effect differed. We associate the more anterior effect in hearing readers with stronger co-activation of, and competition among, phonological representations. Thus, deaf readers use lexical competition to recognize visual words, but it is primarily restricted to orthographic representations.

Early use of phonological codes in deaf readers: An ERP study

Previous studies suggest that deaf readers use phonological information of words when it is explicitly demanded by the task itself. However, whether phonological encoding is automatic remains controversial. The present experiment examined whether adult congenitally deaf readers show evidence of automatic use of phonological information during visual word recognition. In an ERP masked priming lexical decision experiment, deaf participants responded to target words preceded by a pseudohomophone (koral - CORAL) or an orthographic control prime (toral - CORAL). Responses were faster for the pseudohomophone than for the orthographic control condition. The N250 and N400 amplitudes were reduced for the pseudohomophone when compared to the orthographic control condition. Furthermore, the magnitude of both the behavioral and the ERP pseudohomophone effects in deaf readers was similar to that of a group of well-matched hearing controls. These findings reveal that phonological encoding is available to deaf readers from the early stages of visual word recognition. Finally, the pattern of correlations of phonological priming with reading ability suggested that the amount of sub-lexical use of phonological information could be a main contributor to reading ability for hearing but not for deaf readers.

Does Top-Down Feedback Modulate the Encoding of Orthographic Representations During Visual-Word Recognition?

In masked priming lexical decision experiments, there is a matched-case identity advantage for nonwords, but not for words (e.g., ERTAR-ERTAR <  ertar-ERTAR; ALTAR-ALTAR = altar-ALTAR). This dissociation has been interpreted in terms of feedback from higher levels of processing during orthographic encoding. Here, we examined whether a matched-case identity advantage also occurs for words when top-down feedback is minimized. We employed a task that taps prelexical orthographic processes: the masked prime same-different task. For "same" trials, results showed faster response times for targets when preceded by a briefly presented matched-case identity prime than when preceded by a mismatched-case identity prime. Importantly, this advantage was similar in magnitude for nonwords and words. This finding constrains the interplay of bottom-up versus top-down mechanisms in models of visual-word identification.

The role of letter features in visual-word recognition: Evidence from a delayed segment technique

Do all visual features in a word's constituent letters have the same importance during lexical access? Here we examined whether some components of a word's letters (midsegments, junctions, terminals) are more important than others. To that end, we conducted two lexical decision experiments using a delayed segment technique with lowercase stimuli. In this technique a partial preview appears for 50ms and is immediately followed by the target item. In Experiment 1, the partial preview was composed of terminals+junctions, midsegments+junctions, or midsegments+terminals - a whole preview condition was used as a control. Results only revealed an advantage of the whole preview condition over the other three conditions. In Experiment 2, the partial preview was composed of the whole word except for the deletion of midsegments, junctions, or terminals - we again employed a whole preview condition as a control. Results showed the following pattern in the latency data: whole preview=delay of terminals<delay of junctions<delay of midsegments. Thus, some components of a word's constituent letters are more critical for word identification than others. We examine how the present findings help adjust current models of visual word identification or develop new ones.