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Hearing Readers Dufau et al., 2015
Participants:Monolingual native English speakers
(N=15; Mage=29 )
N400 Window
Trackingthetime-courseofvisualwordrecognitionusingdifferenttypesofword-likestimuli:AnERPstudy
Polina Krom, Natasja Massa, Karen Emmorey, Katherine J. Midgley, & Phillip J. HolcombSan Diego State University
SRS 2019.The research presented here was supported by NSF grant BSC-1756403. Contact: [email protected], [email protected].
o The ability to rapidly recognize visually perceived words is fundamental to skilled reading.
o Previous ERP studies have shown that the lateral distribution of the N170 is sensitive to early processing differences between linguistic (i.e., words) and nonlinguistic (i.e., symbol strings) stimuli [1], while later ERP components such as the N400 are sensitive to lexico-semantic processes (i.e., meaningfulness of stimuli) [2].
o In the present study, we sought to investigate the neurocognitive processes involved in visual word recognition and extended the work of Emmorey et al. by incorporating five-letter consonant strings.
o We focused on the N170 and the N400, which are negative peaks in the ERP waveform around 170 ms and 400 ms, respectively.
[1] Emmorey, K., Midgley, K. J., Kohen, C. B., Sehyr, Z. S., & Holcomb, P. J. (2017). The N170 ERP component differs in laterality, distribution, and association with continuous reading measures for deaf and hearing readers. Neuropsychologia, 106, 298-309.
[2] Yum, Y. N., Holcomb, P. J., & Grainger, J. (2011). Words and pictures: An electrophysiological investigation of domain specific processing in native Chinese and English speakers. Neuropsychologia, 49(7), 1910-1922.
N170 Window
o Collect data from deaf readers and see if we find a symmetrical N170 effect for consonant strings as we do for words in Emmorey et al., (see figure 1b).
o Use linear mixed effects regression modeling (LMER) to explore whether our online neural measures of word processing are associated with behavioral reading test scores.
o Consonant strings produced a larger N170 over left compared to right occipital sites similar to what Emmorey et al. reported for word stimuli.
o At this early point of processing (170 ms), consonant strings are treated as linguistic stimuli.
o Symbol strings did not show this asymmetry, therefore suggesting that they are not treated as linguistic units.
o Later (300-500 ms) consonant strings differed from words with words showing large lexical-semantic N400 differences.
Introduction ERP Results
Future Directions
References
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Methods
EEG data was recorded continuously from 39 scalp sites
and averaged off-line to form ERPs time-locked to word onset.
Task:Go/no-go repetition detection
Stimuli:Three types of word-like stimuli: v wordsv consonant stringsv symbol strings
100 trials in each condition
Conclusions
RL
120-240 ms
Deaf ReadersEmmorey et al., 2017
Hearing ReadersEmmorey et al., 2017
Words Symbol Strings Symbol StringsWords
Fig. 1 a Fig. 1 b
Pz
Time (ms)
300-500 ms
Symbol StringsConsonant Strings
O9/O10 O9/O10WordsConsonant Strings
In the N170 time window (120-240 ms) hearing readers produced greater negativity for consonants than symbols at left hemisphere (LH) occipital sites.
In the N400 time window (300-500 ms) hearing readers produced greater negativity for words than consonants strings at centro-parietal sites.
Pz
-3.0µv
3.0µv
Left HemisphereRight Hemisphere
RL
2µv2µv
--
200200
400 600
The N400 voltage map shows the difference in negativity between words and consonant strings.
RL
-4.0µv
4.0µv
The N170 voltage maps show an asymmetry for consonants strings and a bilateral distribution for symbol strings.
