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.

N/P150.There was a significant interaction between A-P distribution and group, F(1,34) = 7.03, p = .012,: the effect of case was larger for deaf than hearing participants at posterior electrodes (F = 6.93, p = .013) but not at anterior electrodes (F <1).
There was a significant interaction between lexicality and group, F(1,34) = 4.16, p = .049,: the effect of case was larger for deaf than hearing participants for pseudowords (F = 9.13, p = .005) but not words (F < 1).

N250.
There was a significant interaction between A-P distribution and group, F(1,34) = 6.8, p = .013,: the effect of case was larger for deaf than hearing participants at posterior (F = 5.6, p = .024) but not at anterior electrodes (F <1).
There was a significant interaction between hemisphere, lexicality and group, F(1,34) = 4.43, p = .043,: the effect of case was larger for deaf than hearing participants for pseudowords at the left hemisphere electrode sites (F = 8.64, p = .006; remaining ps >.1).

N400.
There was a significant interaction between hemisphere and group, F(1,34) = 6.34, p = .017,: the effect of case was larger for deaf than hearing participants at right sites (F = 6.25, p = .017) but not left hemisphere sites (F < 1).
Supplementary [17] for the same approach). We contrasted word and pseudoword targets preceded by an identity prime (mismatched case) or an unrelated prime (half of the unrelated items in lowercase and half in uppercase).

Behavioural results:
Separate ANOVAs with the within subjects factors Lexicality (Words vs. Pseudowords) and Repetition (Identity vs. Unrelated) were run for the latency and accuracy data. List was included in the analysis as a dummy factor. Incorrect responses (8.7 %) and lexical decision times above and below the 2.5 SDs of the average per participant and condition (1.1 %).
The ANOVA on the latency data showed that response times to words were faster than to

ERP results
Figure 5 (panel b) shows the ERP waves for words and pseudowords preceded by mismatched case identity primes and unrelated primes. After a brief negative going potential peaking around 50 ms, there is a large positive potential peaking around 200 ms. Following this peak, for words only, the repetition condition shows larger positive amplitude values than the unrelated condition. No differences are apparent for pseudowords.
Words and pseudowords were submitted to separate mass univariate analysis analogous to those of the main comparison in this study (repeated measures, two-tailed t-tests at each sampling point between 50 and 550 ms at 15 scalp electrodes, using an FDR level of 5%).
Results for word targets showed significant repetition priming effects sporadically between 160 and 168 ms at anterior left electrodes. Widely distributed differences were found between 200 and 304 ms and finally, differences in posterior electrodes were found between 380 and 488 ms. No differences were found for pseudoword targets. That is, we found a repetition priming effect on the N250 and N400 components for word but not for pseudoword targets.