Marta Vergara-Martínez

The processing of consonants and vowels during letter identity and letter position assignment in visual-word recognition: An ERP study

Recent research suggests that there is a processing distinction between consonants and vowels in visual-word recognition. Here we conjointly examine the time course of consonants and vowels in processes of letter identity and letter position assignment. Event related potentials (ERPs) were recorded while participants read words and pseudowords in a lexical decision task. The stimuli were displayed under different conditions in a masked priming paradigm with a 50-ms SOA: (i) identity/baseline condition e.g., chocolate-CHOCOLATE); (ii) vowels-delayed condition (e.g., choc_l_te-CHOCOLATE); (iii) consonants-delayed condition (cho_o_ate-CHOCOLATE); (iv) consonants-transposed condition (cholocate-CHOCOLATE); (v) vowels-transposed condition (chocalote-CHOCOLATE), and (vi) unrelated condition (editorial-CHOCOLATE). Results showed earlier ERP effects and longer reaction times for the delayed-letter compared to the transposed-letter conditions. Furthermore, at early stages of processing, consonants may play a greater role during letter identity processing. Differences between vowels and consonants regarding letter position assignment are discussed in terms of a later phonological level involved in lexical retrieval.

Orthographic neighborhood effects as a function of word frequency: an event-related potential study.

The present study assessed the mechanisms and time course by which orthographic neighborhood size (ON) influences visual word recognition. ERPs were recorded to words that varied in ON and in word frequency while participants performed a semantic categorization task. ON was measured with the Orthographic Levenshtein Distance (OLD20), a richer metric of orthographic similarity than the traditional Colthearts N metric. The N400 effects of ON (260-500 ms) were larger and showed a different scalp distribution for low than for high frequency words, which is consistent with proposals that suggest lateral inhibitory mechanisms at a lexical level. The ERP ON effects had a shorter duration and different scalp distribution than the effects of word frequency (mainly observed between 380-600 ms) suggesting a transient activation of the subset of orthographically similar words in the lexical network compared to the impact of properties of the single words.

ERP correlates of inhibitory and facilitative effects of constituent frequency in compound word reading.

In the process of reading compound words, those with high-frequency second constituents are recognized faster than the ones with low-frequency second constituents. However, the role of the first constituent still remains unclear. In the present study, the time course of the frequency effects for both constituents was assessed using Basque compound words embedded in sentences while electrophysiological measures (ERPs) were recorded (Basque is a language with a high frequency of compound words, both right and left-headed). Subjects responded to comprehension questions that were not focused on the compound words. The results revealed that high-frequency first constituents elicited larger negativities starting very early (100-300 ms time window), while low-frequency second constituents elicited larger N400 amplitudes than high-frequency second constituents. Following an activation-verification framework, we argue that the early negativity difference reflects candidate triggering, whereas the N400 difference for the second constituent reflects the cost of its selection and integration for the whole-word meaning to be accessed.

Resolving the locus of cAsE aLtErNaTiOn effects in visual word recognition: Evidence from masked priming

Determining the factors that modulate the early access of abstract lexical representations is imperative for the formulation of a comprehensive neural account of visual-word identification. There is a current debate on whether the effects of case alternation (e.g., tRaIn vs. train) have an early or late locus in the word-processing stream. Here we report a lexical decision experiment using a technique that taps the early stages of visual-word recognition (i.e., masked priming). In the design, uppercase targets could be preceded by an identity/unrelated prime that could be in lowercase or alternating case (e.g., table-TABLE vs. crash-TABLE; tAbLe-TABLE vs. cRaSh-TABLE). Results revealed that the lowercase and alternating case primes were equally effective at producing an identity priming effect. This finding demonstrates that case alternation does not hinder the initial access to the abstract lexical representations during visual-word recognition.

ERP correlates of letter identity and letter position are modulated by lexical frequency.

The encoding of letter position is a key aspect in all recently proposed models of visual-word recognition. We analyzed the impact of lexical frequency on letter position assignment by examining the temporal dynamics of lexical activation induced by pseudowords extracted from words of different frequencies. For each word (e.g., BRIDGE), we created two pseudowords: A transposed-letter (TL: BRIGDE) and a replaced-letter pseudoword (RL: BRITGE). ERPs were recorded while participants read words and pseudowords in two tasks: Semantic categorization (experiment 1) and lexical decision (experiment 2). For high-frequency stimuli, similar ERPs were obtained for words and TL-pseudowords, but the N400 component to words was reduced relative to RL-pseudowords, indicating less lexical/semantic activation. In contrast, TL- and RL-pseudowords created from low-frequency stimuli elicited similar ERPs. Behavioral responses in the lexical decision task paralleled this asymmetry. The present findings impose constraints on computational and neural models of visual-word recognition.

The ERP signature of the contextual diversity effect in visual word recognition

Behavioral experiments have revealed that words appearing in many different contexts are responded to faster than words that appear in few contexts. Although this contextual diversity (CD) effect has been found to be stronger than the word-frequency (WF) effect, it is a matter of debate whether the facilitative effects of CD and WF reflect the same underlying mechanisms. The analysis of the electrophysiological correlates of CD may shed some light on this issue. This experiment is the first to examine the ERPs to high- and low-CD words when WF is controlled for. Results revealed that while high-CD words produced faster responses than low-CD words, their ERPs showed larger negativities (225–325 ms) than low-CD words. This result goes in the opposite direction of the ERP WF effect (high-frequency words elicit smaller N400 amplitudes than low-frequency words). The direction and scalp distribution of the CD effect resembled the ERP effects associated with “semantic richness.” Thus, while apparently related, CD and WF originate from different sources during the access of lexical-semantic representations.

Eye movements when reading sentences with handwritten words

The examination of how we read handwritten words (i.e., the original form of writing) has typically been disregarded in the literature on reading. Previous research using word recognition tasks has shown that lexical effects (e.g., the word-frequency effect) are magnified when reading difficult handwritten words. To examine this issue in a more ecological scenario, we registered the participants’ eye movements when reading handwritten sentences that varied in the degree of legibility (i.e., sentences composed of words in easy vs. difficult handwritten style). For comparison purposes, we included a condition with printed sentences. Results showed a larger reading cost for sentences with difficult handwritten words than for sentences with easy handwritten words, which in turn showed a reading cost relative to the sentences with printed words. Critically, the effect of word frequency was greater for difficult handwritten words than for easy handwritten words or printed words in the total times on a target word, but not on first-fixation durations or gaze durations. We examine the implications of these findings for models of eye movement control in reading.

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

In the masked priming technique, physical identity between prime and target enjoys an advantage over nominal identity in nonwords (GEDA-GEDA faster than geda-GEDA). However, nominal identity overrides physical identity in words (e.g., REAL-REAL similar to real-REAL). Here we tested whether the lack of an advantage of the physical identity condition for words was due to top-down feedback from phonological-lexical information. We examined this issue with deaf readers, as their phonological representations are not as fully developed as in hearing readers. Results revealed that physical identity enjoyed a processing advantage over nominal identity not only in nonwords but also in words (GEDA-GEDA faster than geda-GEDA; REAL-REAL faster than real-REAL). This suggests the existence of fundamental differences in the early stages of visual word recognition of hearing and deaf readers, possibly related to the amount of feedback from higher levels of information.

Are You Taking the Fastest Route to the RESTAURANT

Most words in books and digital media are written in lowercase. The primacy of this format has been brought out by different experiments showing that common words are identified faster in lowercase (e.g., molecule) than in uppercase (MOLECULE). However, there are common words that are usually written in uppercase (street signs, billboards; e.g., STOP, PHARMACY). We conducted a lexical decision experiment to examine whether the usual letter-case configuration (uppercase vs. lowercase) of common words modulates word identification times. To this aim, we selected 78 molecule-type words and 78 PHARMACY-type words that were presented in lowercase or uppercase. For molecule-type words, the lowercase format elicited faster responses than the uppercase format, whereas this effect was absent for PHARMACY-type words. This pattern of results suggests that the usual letter configuration of common words plays an important role during visual word processing.

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

Abstract 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. HighlightsA debated issue is whether deaf readers use phonological codes during reading.We conducted a masked priming experiment with pseudohomophone primes.The phonological priming effect was similar for deaf and hearing controls.Deaf and hearing readers had similar phonological priming on the N250 and N400.In deaf readers, a higher reading ability was correlated with late ERP effects.