The Speed of Orthographic Processing during Lexical Decision: Electrophysiological Evidence for Independent Coding of Letter Identity and Letter Position in Visual Word Recognition

2008 ◽  
Vol 20 (7) ◽  
pp. 1283-1299 ◽  
Author(s):  
Marina Mariol ◽  
Corentin Jacques ◽  
Marie-Anne Schelstraete ◽  
Bruno Rossion
Keyword(s):  
Lexical Decision ◽  
Time Course ◽  
Event Related Potentials ◽  
Letter Position ◽  
Decision Task ◽  
Letter Identity ◽  
Two Factors ◽  
Related Potentials ◽  
Open Question ◽  
Double Letters

Adults can decide rapidly if a string of letters is a word or not. However, the exact time course of this discrimination is still an open question. Here we sought to track the time course of this discrimination and to determine how orthographic information—letter position and letter identity—is computed during reading. We used a go/no-go lexical decision task while recording event-related potentials (ERPs). Subjects were presented with single words (go trials) and pseudowords (no-go trials), which varied in orthographic conformation, presenting either a double consonant frequently doubled (i.e., “ss”) or never doubled (i.e., “zz”) (identity factor); and a position of the double consonant was which either legal or illegal (position factor), in a 2 × 2 factorial design. Words and pseudowords clearly differed as early as 230 msec. At this latency, ERP waveforms were modulated both by the identity and by the position of letters: The fronto-central no-go N2 was the smallest in amplitude and peaked the earliest to pseudowords presenting both an illegal double-letter position and an identity never encountered. At this stage, the two factors showed additive effects, suggesting an independent coding. The factors of identity and position of double letters interacted much later in the process, at the P3 level, around 300–400 msec on frontal and central sites, in line with the lexical decision data obtained in the behavioral study. Overall, these results show that the speed of lexical decision may depend on orthographic information coded independently by the identity and position of letters in a word.

From Orthography to Phonetics: ERP Measures of Grapheme-to-Phoneme Conversion Mechanisms in Reading

2004 ◽  
Vol 16 (2) ◽  
pp. 301-317 ◽  
Author(s):  
Alice Mado Proverbio ◽  
Liza Vecchi ◽  
Alberto Zani
Keyword(s):  
Word Recognition ◽  
Visual Word Recognition ◽  
Time Course ◽  
Event Related Potentials ◽  
Visual Word ◽  
Decision Task ◽  
Lexical Frequency ◽  
Magnetic Source Imaging ◽  
Pure Alexia ◽  
Related Potentials

Neuroimaging has provided evidence that the first stages of visual word recognition activate a visual word-form center localized in the left extrastriate cortex (fusiform gyrus). Accordingly, neurological cases of patients suffering from pure alexia reported the left posterior occipital lobe as the possible locus of orthographic analysis. There is less agreement in the literature about which brain structures are involved in the subsequent stages of word processing and, in particular, their time course of activation. Functional magnetic resonance imaging and magnetic source imaging studies recently reported data that could indicate a dual route model of reading. These findings are particularly relevant to studies on the functional deficits associated with phonological and surface dyslexia. There is evidence for the existence of two different brain mechanisms supporting phonological processing in visual word recognition: one mechanism subserving “assembled phonology” for reading letter strings and another one subserving “addressed phonology” for reading meaningful words. However, available knowledge on the time course and neural locus of grapheme-to-phoneme conversion mechanisms in reading is still inadequate. In this study, we compared processing of meaningful and meaningless Italian words in a task requiring a phonemic/phonetic decision task. Stimuli were 1152 different orthographic stimuli presented in the central visual field. Half the stimuli were Italian words (with a high or low frequency of occurrence), the other half were meaningless strings of letters (legal pseudowords and letter strings). Event-related potentials were recorded from 28 scalp sites in 10 Italian university students. The task consisted of deciding about the presence/absence of a given “phone” in the hypothetical enunciation of word read: for example, “Is there a/k/in cheese?”. Results showed that lexical frequency and orthographical regularity affected linguistic processing within 150 msec poststimulus. Indeed, the amplitude of a centroparietal P150 varied as a function of stimulus type, being larger in response to high-frequency words than to lowfrequency ones and to words and pseudowords than to letter strings. This component might index visual categorization processes and recognition of familiar objects, being highly sensitive to orthographic regularity and “ill-formedness” of words. The amplitude of the P150 was the same in response to well-formed meaningless and to meaningful words, when these latter had a low lexical frequency. This might indicate that highly familiar words are recognized as meaningful unitary visual objects at very early stages of processing, through a visual route to an orthographic input lexicon. Moreover, the amplitude of the negativity recorded between 250 and 350 msec showed an anteroposterior topographic dissociation for access to the phonemic representation of wellor ill-formed strings of characters. Brain responses were larger over the left occipito-temporal regions during reading of words and pseudowords and over the left frontal regions during reading of letter strings.

scholarly journals Are Vowels and Consonants Processed Differently? Event-related Potential Evidence with a Delayed Letter Paradigm

2009 ◽  
Vol 21 (2) ◽  
pp. 275-288 ◽  
Author(s):  
Manuel Carreiras ◽  
Margaret Gillon-Dowens ◽  
Marta Vergara ◽  
Manuel Perea
Keyword(s):  
Word Recognition ◽  
Lexical Decision ◽  
Response Times ◽  
Event Related Potentials ◽  
Simultaneous Presentation ◽  
Event Related Potential ◽  
Baseline Condition ◽  
Decision Task ◽  
Related Potentials ◽  
Processing Event

To investigate the neural bases of consonant and vowel processing, event-related potentials (ERPs) were recorded while participants read words and pseudowords in a lexical decision task. The stimuli were displayed in three different conditions: (i) simultaneous presentation of all letters (baseline condition); (ii) presentation of all letters, except that two internal consonants were delayed for 50 msec (consonants-delayed condition); and (iii) presentation of all letters, except that two internal vowels were delayed for 50 msec (vowels-delayed condition). The behavioral results showed that, for words, response times in the consonants-delayed condition were longer than in the vowels-delayed condition, which, in turn, were longer than in the baseline condition. The ERPs showed that, starting as early as 150 msec, words in the consonants-delayed condition produced a larger negativity than words in vowels-delayed condition. In addition, there were peak latency differences and amplitude differences in the P150, N250, P325, and N400 components between the baseline and the two letter-delayed conditions. We examine the implications of these findings for models of visual-word recognition and reading.

An ERP Investigation of Semantic Priming, Repetition Priming, and Negative Priming in Schizophrenic Patients

2006 ◽  
Vol 20 (3) ◽  
pp. 195-211 ◽  
Author(s):  
Michael Wagner ◽  
Lioba Baving ◽  
Patrick Berg ◽  
Rudolf Cohen ◽  
Brigitte Rockstroh
Keyword(s):  
Negative Priming ◽  
Repetition Priming ◽  
Event Related Potentials ◽  
Decision Task ◽  
Positive Priming ◽  
Retrieval Processes ◽  
Schizophrenic Patients ◽  
Related Potentials ◽  
Late Positive Complex ◽  
Automatic Memory

The processing of attended and nonattended stimuli in schizophrenic patients was examined with event-related potentials (ERPs) in a lexical decision task. In positive semantic and repetition priming the N400 amplitude did not differ between a group of 17 medicated schizophrenic patients and a group of 20 matched healthy controls. However, negative priming affected the N400 only in controls. Reaction time effects were dissociated from these ERP effects, with patients showing stronger positive priming than controls but identical negative priming. The semantic processes related to the N400 appear to be intact in schizophrenic patients, but patients seem to incorporate less context information (about the nonattended prime) in their episodic memory traces. A stronger increase of the posterior late positive complex in parallel to the stronger positive priming in schizophrenic patients may reflect relatively stronger automatic memory retrieval processes in patients.

scholarly journals Increased Neural Efficiency in Visual Word Recognition: Evidence from Alterations in Event-Related Potentials and Multiscale Entropy

Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 304
Author(s):  
Kelsey Cnudde ◽  
Sophia van Hees ◽  
Sage Brown ◽  
Gwen van der Wijk ◽  
Penny M. Pexman ◽  
...  
Keyword(s):  
Word Recognition ◽  
Visual Word Recognition ◽  
Response Times ◽  
Event Related Potentials ◽  
Visual Word ◽  
Multiscale Entropy ◽  
Decision Task ◽  
Late Positive Component ◽  
Domain Specific ◽  
Related Potentials

Visual word recognition is a relatively effortless process, but recent research suggests the system involved is malleable, with evidence of increases in behavioural efficiency after prolonged lexical decision task (LDT) performance. However, the extent of neural changes has yet to be characterized in this context. The neural changes that occur could be related to a shift from initially effortful performance that is supported by control-related processing, to efficient task performance that is supported by domain-specific processing. To investigate this, we replicated the British Lexicon Project, and had participants complete 16 h of LDT over several days. We recorded electroencephalography (EEG) at three intervals to track neural change during LDT performance and assessed event-related potentials and brain signal complexity. We found that response times decreased during LDT performance, and there was evidence of neural change through N170, P200, N400, and late positive component (LPC) amplitudes across the EEG sessions, which suggested a shift from control-related to domain-specific processing. We also found widespread complexity decreases alongside localized increases, suggesting that processing became more efficient with specific increases in processing flexibility. Together, these findings suggest that neural processing becomes more efficient and optimized to support prolonged LDT performance.

Neural Biases to Covert and Overt Signals of Fear: Dissociation by Trait Anxiety and Depression

2007 ◽  
Vol 19 (10) ◽  
pp. 1595-1608 ◽  
Author(s):  
Leanne M. Williams ◽  
Andrew H. Kemp ◽  
Kim Felmingham ◽  
Belinda J. Liddell ◽  
Donna M. Palmer ◽  
...  
Keyword(s):  
Trait Anxiety ◽  
Time Course ◽  
Event Related Potentials ◽  
Anxiety And Depression ◽  
Controlled Processing ◽  
Parallel Networks ◽  
Related Potentials ◽  
Conscious Attention ◽  
The Impact ◽  
Emotion Encoding

Although biases toward signals of fear may be an evolutionary adaptation necessary for survival, heightened biases may be maladaptive and associated with anxiety or depression. In this study, event-related potentials (ERPs) were used to examine the time course of neural responses to facial fear stimuli (versus neutral) presented overtly (for 500 msec with conscious attention) and covertly (for 10 msec with immediate masking to preclude conscious awareness) in 257 nonclinical subjects. We also examined the impact of trait anxiety and depression, assessed using psychometric ratings, on the time course of ERPs. In the total subject group, controlled biases to overtly processed fear were reflected in an enhancement of ERPs associated with structural encoding (120–220 msec) and sustained evaluation persisting from 250 msec and beyond, following a temporo-occipital to frontal topography. By contrast, covert fear processing elicited automatic biases, reflected in an enhancement of ERPs prior to structural encoding (80–180 msec) and again in the period associated with automatic orienting and emotion encoding (230–330 msec), which followed the reverse frontal to temporo-occipital topography. Higher levels of trait anxiety (in the clinical range) were distinguished by a heightened bias to covert fear (speeding of early ERPs), compared to higher depression which was associated with an opposing bias to overt fear (slowing of later ERPs). Anxiety also heightened early responses to covert fear, and depression to overt fear, with subsequent deficits in emotion encoding in each case. These findings are consistent with neural biases to signals of fear which operate automatically and during controlled processing, feasibly supported by parallel networks. Heightened automatic biases in anxiety may contribute to a cycle of hypervigilance and anxious thoughts, whereas depression may represent a “burnt out” emotional state in which evaluation of fear stimuli is prolonged only when conscious attention is allocated.

Behavioral and Electrophysiological Study of Phonological Priming between Bisyllabic Spoken Words

2001 ◽  
Vol 13 (1) ◽  
pp. 121-143 ◽  
Author(s):  
Nicolas Dumay ◽  
Abdelrhani Benraïss ◽  
Brian Barriol ◽  
Cécile Colin ◽  
Monique Radeau ◽  
...  
Keyword(s):  
Electrophysiological Study ◽  
Reaction Times ◽  
Event Related Potentials ◽  
Auditory Presentation ◽  
Decision Task ◽  
Phonological Priming ◽  
Priming Effects ◽  
Related Potentials ◽  
N400 Component ◽  
Lexical Processes

Phonological priming between bisyllabic (CV.CVC) spoken items was examined using both behavioral (reaction times, RTs) and electrophysiological (event-related potentials, ERPs) measures. Word and pseudoword targets were preceded by pseudoword primes. Different types of final phonological overlap between prime and target were compared. Critical pairs shared the last syllable, the rime or the coda, while unrelated pairs were used as controls. Participants performed a target shadowing task in Experiment 1 and a delayed lexical decision task in Experiment 2. RTs were measured in the first experiment and ERPs were recorded in the second experiment. The RT experiment was carried out under two presentation conditions. In Condition 1 both primes and targets were presented auditorily, while in Condition 2 the primes were presented visually and the targets auditorily. Priming effects were found in the unimodal condition only. RTs were fastest for syllable overlap, intermediate for rime overlap, and slowest for coda overlap and controls that did not differ from one another. ERPs were recorded under unimodal auditory presentation. ERP results showed that the amplitude of the auditory N400 component was smallest for syllable overlap, intermediate for rime overlap, and largest for coda overlap and controls that did not differ from one another. In both experiments, the priming effects were larger for word than for pseudoword targets. These results are best explained by the combined influences of nonlexical and lexical processes, and a comparison of the reported effects with those found in monosyllables suggests the involvement of rime and syllable representations.

The Interaction of Word Frequency and Stimulus Quality in the Lexical Decision Task: Now you See It, Now you Don't

1988 ◽  
Vol 40 (4) ◽  
pp. 757-770 ◽  
Author(s):  
J. M. Wilding
Keyword(s):  
Word Recognition ◽  
Lexical Decision ◽  
Lexical Decision Task ◽  
Word Frequency ◽  
Decision Task ◽  
Stimulus Quality ◽  
Joint Effects ◽  
Two Factors

Two experiments are reported that examined the joint effects of word frequency and stimulus quality in the context of a lexical decision task. In the first experiment the interval between response to a stimulus and onset of the next stimulus was 0.8 sec, and the effect of the two factors was additive. In the second this interval was 3.3 sec, and the effect of reducing stimulus quality was greater for infrequent words than for frequent words. This is similar to the result of Norris (1984). The inability of current models of word recognition to explain this finding is discussed.

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