Pseudoword Condition Research Articles

Neural correlates of semantic matching in indirect priming

Electrophysiological and functional neuroimaging studies have demonstrated the role of a left temporo-parietal brain network in prospective processing during direct priming (“body” – “hand”) using a short stimulus onset asynchrony (SOA). In contrast, indirect priming (“lion” – “stripes” related through “tiger”) has been related to the activation of right hemisphere regions such as the supramarginal and middle frontal gyri and the insula involved in automatic semantic processing. Postlexical retrospective strategies like semantic matching, compound cue or episodic retrieval have been largely neglected even though there is consistent evidence of their contribution to direct and indirect priming. The present study was designed to map the brain regions participating in semantic priming based on postlexical retrospective semantic matching. 16 right-handed Spanish speakers (ages 20–40, 50 % male) were given a visual lexical decision task in a 1.5 T scanner with a TR of 3.5 s to obtain BOLD activations. In order to reduce the effects of automatic spreading activation on priming we used a long SOA (800 ms). To minimize the effects of expectancy, we increased the related-unrelated ratio to 1:2 (20 related, 40 unrelated, 20 pseudowords) and employed an indirect priming paradigm with weakly associated targets to enhance the effects of semantic matching. Each 3500 ms trial consisted on a fixation screen for 1000 ms followed by a 100 ms black screen, then the prime word for 600 ms, another black screen for 200 ms, the target word/pseudoword for 600 ms and finally a response screen for 1000 ms. Response time was longer for pseudowords compared to related and unrelated targets. An increased activity was found in lIFG for related pairs and pseudowords, whereas a large cluster of activation was found in left fusiform gyrus for unrelated pairs. Right insula was also activated for unrelated and pseudoword conditions. Furthermore, all conditions showed a decreased activity in left precuneus/parieto-occipital sulcus. These data addressed the role of frontal, temporal, parietal and insular regions in retrospective semantic matching with a differential pattern according to the lexical retrieval, selection and inhibition processes required to make a lexical decision.

Taxonomically-related Word Pairs Evoke both N400 and LPC at Long SOA in Turkish.

Semantic priming in Turkish was examined in 36 right-handed healthy participants in a delayed lexical decision task via taxonomic relations using EEG. Prime-target relations included related- unrelated- and pseudo-words. Taxonomically related words at long stimulus onset asynchrony (SOA) were shown to modulate N400 and late positive component (LPC) amplitudes. N400 semantic priming effect in the time window of 300-500 ms was the largest for pseudo-words, intermediate for semantically-unrelated targets, and smallest for semantically-related targets as a reflection of lexical-semantic retrieval. This finding contributes to the ERP literature showing how remarkably universal the N400 brain potential is, with similar effects across languages and orthography. The ERP data also revealed different influences of related, unrelated, and pseudo-word conditions on the amplitude of the LPC. Attention scores and mean LPC amplitudes of related words in parietal region showed a moderate correlation, indicating LPC may be related to "relationship-detection process".

Electrophysiological correlates of character transposition in two-character Chinese word identification

The present study investigated brain activity elicited by character transposition processing of two-character Chinese words using event-related potentials (ERPs) with a two-target rapid serial visual presentation (RSVP) task. The behavioral results showed higher accuracy with canonical and transposed words than pseudowords in the short stimulus onset asynchrony (SOA, 249 ms) condition, but not in the long SOA (581 ms) condition. Additionally, relative to the pseudoword condition, the ERP results indicated that the canonical and transposed words elicited statistically less negative N250 and N400 amplitudes. Furthermore, both the canonical and transposed words revealed no significant differences in the early N100, P200, and N250 components, whereas a significant difference was observed in the N400 amplitude regardless of the SOAs between the two constituent characters, indicating less semantic activation. Taken together, our electrophysiological data indicate that early ERP components are not sensitive to Chinese character transposition. In contrast, such morpheme transposition affects the semantic processing of Chinese compound words.

When one pseudoword elicits larger P600 than another: a study on the role of reprocessing in anomalous sentence comprehension

ABSTRACT Reprocessing has been speculated to be a late higher-level cognitive process in the P600 time window in event-related potential (ERP) studies. However, uncertainties regarding the P600 as an index of reprocessing have obscured the role of reprocessing in sentence comprehension. In this study, we compared meaningless pseudowords with or without a homophonic repairing clue (homophonic pseudoword vs. ordinary pseudoword) and semantically-plus-syntactically violated real words (doubly violated) to investigate the role of reprocessing in language comprehension. All anomalous conditions elicited significant typical central-parietal P600 effects. The homophonic pseudoword condition elicited a significantly larger P600 effect than the other two anomalous conditions. No significant difference was found between the P600 effects in the ordinary pseudoword and the doubly violated real-word conditions. These results demonstrate an association between reprocessing and the observed P600 effects, supporting an active role of reprocessing in sentence comprehension. Possible implications for language processing models are also discussed.

Word Meaning Contributes to Free Recall Performance in Supraspan Verbal List-Learning Tests.

Supraspan verbal list-learning tests, such as the Rey Auditory Verbal Learning Test (RAVLT), are classic neuropsychological tests for assessing verbal memory. In this study, we investigated the impact of the meaning of the words to be learned on three memory stages [short-term recall (STR), learning, and delayed recall (DR)] in a cohort of 447 healthy adults. First, we compared scores obtained from the RAVLT (word condition) to those of an alternative version of this test using phonologically similar but meaningless items (pseudoword condition) and observed how each score varied as a function of age and sex. Then, we collected the participants’ self-reported strategies to retain the word and pseudoword lists and examined if these strategies mediated the age and sex effects on memory scores. The word condition resulted in higher memory scores than pseudoword condition at each memory stage and even canceled out, for the learning stage, the detrimental effect of age that was observed for the short-term and DR. When taking sex into account, the word advantage was observed only in women for STR. The self-reported strategies, which were similar for words and pseudowords, were based on the position of the item on the list (word: 53%, pseudoword: 37%) or the meaning of the item (word: 64%, pseudoword: 58%) and were used alone or in combination. The best memory performance was associated with the meaning strategy in the word condition and with the combination of the meaning and position strategies in the pseudoword condition. Finally, we found that the word advantage observed in women for STR was mediated by the use of the meaning strategy. The RAVLT scores were thus highly dependent on word meaning, notably because it allowed efficient semantic knowledge-based strategies. Within the framework of Tulving’s declarative memory model, these results are at odds with the depiction of the RAVLT as a verbal episodic memory test as it is increasingly referred to in the literature.

Revealing the Dynamic Brain Connectivity from Perception of Speech Sound to Semantic Processing by EEG

Understanding brain processing mechanisms from the perception of speech sounds to high-level semantic processing is vital for effective human–robot communication. In this study, 128-channel electroencephalograph (EEG) signals were recorded when subjects were listening to real and pseudowords in Mandarin. By using an EEG source reconstruction method and a sliding-window Granger causality analysis, we analyzed the dynamic brain connectivity patterns. Results showed that the bilateral temporal cortex (lTC and rTC), the bilateral motor cortex (lMC and rMC), the frontal cortex (FC), and the occipital cortex (OC) were recruited in the process, with complex patterns in the real word condition than in the pseudoword condition. The spatial pattern is basically consistent with previous functional MRI studies on the understanding of spoken Chinese. For the real word condition, speech perception and processing involved different connection patterns in the initial phoneme perception and processing phase, the phonological processing and lexical selection phase, and the semantic integration phase. Specifically, compared with pseudowords, a hub region in the FC and unique patterns of lMC → rMC and lTC → FC connectivity were found during processing real words after 180 ms, while a distributed network of temporal, motor, and frontal brain areas was involved after 300 ms. This may be related to semantic processing and integration. The involvement of both bottom-up input and top-down modulation in real word processing may support the previously proposed TRACE model. In sum, the findings of this study suggest that representations of speech involve dynamic interactions among distributed brain regions that communicate through time-specific functional networks.

Acquisition of Finnish derivational morphology: School-age children and young adults

The current study examined how morpho-semantic processing of derivational morphology develops from later childhood through adolescence to adulthood in Finnish. Finnish is a synthetic language rich both in derivation and inflection. It has been suggested that children gradually acquire the ability to process morphologically complex word structures. However, this development could be delayed because of the complex derivational morphology in Finnish. To assess this, three age groups of Finnish native speakers participated in a priming study, in which they made a visual lexical decision for the target words. There were three types of primes: morphologically related words, pseudowords, and unrelated words. The reaction times results showed a significant difference between all the groups, which implies that the word processing is still developing in adolescence. The error rates unveiled a similar pattern to reaction times. The prime type affected the recognition: words with morphological primes were processed faster than words with pseudoword primes, which in turn were processed faster than words with unrelated primes. Moreover, males made significantly more errors than females with morphological and pseudoword prime conditions.

The neural realm of taxonomic and thematic relation: an fMRI study

ABSTRACTTaxonomic and thematic relations are part of an integrated memory system grounded in the sensory, perceptual and motor systems and distributed across important brain regions. Although essential for human communication and cognition, their neural basis is still a point of controversy. This study used neuroimaging to demonstrate the involvement of the frontal, parietal, occipital and temporal regions in comparison to the control (pseudo-word condition). Subjects underwent functional magnetic resonance imaging (fMRI) during an auditory semantic priming task involving decision-making about similarities of the presented word pairs based on taxonomic and thematic relations. The precise common region was identified as the ventral occipito-temporal cortex. Direct comparison across semantic conditions indicated that the inferior frontal, supramarginal gyrus, medial and anterior temporal poles were involved as key regions for taxonomic relations. Additional regions for thematic relations were not identified, thus implying the possibility of highly variable nature of taxonomic and thematic relation.

Delta, theta, beta, and gamma brain oscillations index levels of auditory sentence processing

A growing number of studies indicate that multiple ranges of brain oscillations, especially the delta (δ, <4Hz), theta (θ, 4–8Hz), beta (β, 13–30Hz), and gamma (γ, 30–50Hz) bands, are engaged in speech and language processing. It is not clear, however, how these oscillations relate to functional processing at different linguistic hierarchical levels. Using scalp electroencephalography (EEG), the current study tested the hypothesis that phonological and the higher-level linguistic (semantic/syntactic) organizations during auditory sentence processing are indexed by distinct EEG signatures derived from the δ, θ, β, and γ oscillations. We analyzed specific EEG signatures while subjects listened to Mandarin speech stimuli in three different conditions in order to dissociate phonological and semantic/syntactic processing: (1) sentences comprising valid disyllabic words assembled in a valid syntactic structure (real-word condition); (2) utterances with morphologically valid syllables, but not constituting valid disyllabic words (pseudo-word condition); and (3) backward versions of the real-word and pseudo-word conditions. We tested four signatures: band power, EEG–acoustic entrainment (EAE), cross-frequency coupling (CFC), and inter-electrode renormalized partial directed coherence (rPDC). The results show significant effects of band power and EAE of δ and θ oscillations for phonological, rather than semantic/syntactic processing, indicating the importance of tracking δ- and θ-rate phonetic patterns during phonological analysis. We also found significant β-related effects, suggesting tracking of EEG to the acoustic stimulus (high-β EAE), memory processing (θ–low-β CFC), and auditory-motor interactions (20-Hz rPDC) during phonological analysis. For semantic/syntactic processing, we obtained a significant effect of γ power, suggesting lexical memory retrieval or processing grammatical word categories. Based on these findings, we confirm that scalp EEG signatures relevant to δ, θ, β, and γ oscillations can index phonological and semantic/syntactic organizations separately in auditory sentence processing, compatible with the view that phonological and higher-level linguistic processing engage distinct neural networks.

The impact of task demand on visual word recognition

The left occipitotemporal cortex has been found sensitive to the hierarchy of increasingly complex features in visually presented words, from individual letters to bigrams and morphemes. However, whether this sensitivity is a stable property of the brain regions engaged by word recognition is still unclear. To address the issue, the current study investigated whether different task demands modify this sensitivity. Participants viewed real English words and stimuli with hierarchical word-likeness while performing a lexical decision task (i.e., to decide whether each presented stimulus is a real word) and a symbol detection task. General linear model and independent component analysis indicated strong activation in the fronto-parietal and temporal regions during the two tasks. Furthermore, the bilateral inferior frontal gyrus and insula showed significant interaction effects between task demand and stimulus type in the pseudoword condition. The occipitotemporal cortex showed strong main effects for task demand and stimulus type, but no sensitivity to the hierarchical word-likeness was found. These results suggest that different task demands on semantic, phonological and orthographic processes can influence the involvement of the relevant regions during visual word recognition.

An fMRI study of concreteness effects in spoken word recognition

BackgroundEvidence for the brain mechanisms recruited when processing concrete versus abstract concepts has been largely derived from studies employing visual stimuli. The tasks and baseline contrasts used have also involved varying degrees of lexical processing. This study investigated the neural basis of the concreteness effect during spoken word recognition and employed a lexical decision task with a novel pseudoword condition.MethodsThe participants were seventeen healthy young adults (9 females). The stimuli consisted of (a) concrete, high imageability nouns, (b) abstract, low imageability nouns and (c) opaque legal pseudowords presented in a pseudorandomised, event-related design. Activation for the concrete, abstract and pseudoword conditions was analysed using anatomical regions of interest derived from previous findings of concrete and abstract word processing.ResultsBehaviourally, lexical decision reaction times for the concrete condition were significantly faster than both abstract and pseudoword conditions and the abstract condition was significantly faster than the pseudoword condition (p < 0.05). The region of interest analysis showed significantly greater activity for concrete versus abstract conditions in the left dorsolateral prefrontal cortex, posterior cingulate and bilaterally in the angular gyrus. There were no significant differences between abstract and concrete conditions in the left superior temporal gyrus or inferior frontal gyrus.ConclusionsThese findings confirm the involvement of the bilateral angular gyrus, left posterior cingulate and left dorsolateral prefrontal cortex in retrieving concrete versus abstract concepts during spoken word recognition. Significant activity was also elicited by concrete words relative to pseudowords in the left fusiform and left anterior middle temporal gyrus. These findings confirm the involvement of a widely distributed network of brain regions that are activated in response to the spoken recognition of concrete but not abstract words. Our findings are consistent with the proposal that distinct brain regions are engaged as convergence zones and enable the binding of supramodal input.

Comprehension of derivational morphemes in words and pseudo-words in semantic variant primary progressive aphasia

Comprehension of derivational morphemes in words and pseudo-words in semantic variant primary progressive aphasia

A Functional Near-Infrared Spectroscopy Study of Lexical Decision Task Supports the Dual Route Model and the Phonological Deficit Theory of Dyslexia

The dual route model (DRM) of reading suggests two routes of reading development: the phonological and the orthographic routes. It was proposed that although the two routes are active in the process of reading; the first is more involved at the initial stages of reading acquisition, whereas the latter needs more reading training to mature. A number of studies have shown that deficient phonological processing is a core deficit in developmental dyslexia. According to the DRM, when the Lexical Decision Task (LDT) is performed, the orthographic route should also be involved when decoding words, whereas it is clear that when decoding pseudowords the phonological route should be activated. Previous functional near-infrared spectroscopy (fNIR) studies have suggested that the upper left frontal lobe is involved in decision making in the LDT. The current study used fNIR to compare left frontal lobe activity during LDT performance among three reading-level groups: 12-year-old children, young adult dyslexic readers, and young adult typical readers. Compared to typical readers, the children demonstrated lower activity under the word condition only, whereas the dyslexic readers showed lower activity under the pseudoword condition only. The results provide evidence for upper left frontal lobe involvement in LDT and support the DRM and the phonological deficit theory of dyslexia.

Investigating Unique Environmental Contributions to the Neural Representation of Written Words: A Monozygotic Twin Study

The visual word form area (VWFA) is a region of left inferior occipitotemporal cortex that is critically involved in visual word recognition. Previous studies have investigated whether and how experience shapes the functional characteristics of VWFA by comparing neural response magnitude in response to words and nonwords. Conflicting results have been obtained, however, perhaps because response magnitude can be influenced by other factors such as attention. In this study, we measured neural activity in monozygotic twins, using functional magnetic resonance imaging. This allowed us to quantify differences in unique environmental contributions to neural activation evoked by words, pseudowords, consonant strings, and false fonts in the VWFA and striate cortex. The results demonstrate significantly greater effects of unique environment in the word and pseudoword conditions compared to the consonant string and false font conditions both in VWFA and in left striate cortex. These findings provide direct evidence for environmental contributions to the neural architecture for reading, and suggest that learning phonology and/or orthographic patterns plays the biggest role in shaping that architecture.

ERP correlates of unexpected word forms in a picture–word study of infants and adults

We tested 14-month-olds and adults in an event-related potentials (ERPs) study in which pictures of familiar objects generated expectations about upcoming word forms. Expected word forms labelled the picture (word condition), while unexpected word forms mismatched by either a small deviation in word medial vowel height (mispronunciation condition) or a large deviation from the onset of the first speech segment (pseudoword condition).Both infants and adults showed sensitivity to both types of unexpected word form. Adults showed a chain of discrete effects: positivity over the N1 wave, negativity over the P2 wave (PMN effect) and negativity over the N2 wave (N400 effect). Infants showed a similar pattern, including a robust effect similar to the adult P2 effect. These observations were underpinned by a novel visualisation method which shows the dynamics of the ERP within bands of the scalp over time. The results demonstrate shared processing mechanisms across development, as even subtle deviations from expected word forms were indexed in both age groups by a reduction in the amplitude of characteristic waves in the early auditory evoked potential.

Memory Traces for Spoken Words in the Brain as Revealed by the Hemodynamic Correlate of the Mismatch Negativity

The mismatch negativity response, considered a brain correlate of automatic preattentive auditory processing, is enhanced for word stimuli as compared with acoustically matched pseudowords. This lexical enhancement, taken as a signature of activation of language-specific long-term memory traces, was investigated here using functional magnetic resonance imaging to complement the previous electrophysiological studies. In passive oddball paradigm, word stimuli were randomly presented as rare deviants among frequent pseudowords; the reverse conditions employed infrequent pseudowords among word stimuli. Random-effect analysis indicated clearly distinct patterns for the different lexical types. Whereas the hemodynamic mismatch response was significant for the word deviants, it did not reach significance for the pseudoword conditions. This difference, more pronounced in the left than right hemisphere, was also assessed by analyzing average parameter estimates in regions of interests within both temporal lobes. A significant hemisphere-by-lexicality interaction confirmed stronger blood oxygenation level-dependent mismatch responses to words than pseudowords in the left but not in the right superior temporal cortex. The increased left superior temporal activation and the laterality of cortical sources elicited by spoken words compared with pseudowords may indicate the activation of cortical circuits for lexical material even in passive oddball conditions and suggest involvement of the left superior temporal areas in housing such word-processing neuronal circuits.

Semantic interference on a phonological task in illiterate subjects

Previous research suggests that learning an alphabetic written language influences aspects of the auditory-verbal language system. In this study, we examined whether literacy influences the notion of words as phonological units independent of lexical semantics in literate and illiterate subjects. Subjects had to decide which item in a word- or pseudoword pair was phonologically longest. By manipulating the relationship between referent size and phonological length in three word conditions (congruent, neutral, and incongruent) we could examine to what extent subjects focused on form rather than meaning of the stimulus material. Moreover, the pseudoword condition allowed us to examine global phonological awareness independent of lexical semantics. The results showed that literate performed significantly better than illiterate subjects in the neutral and incongruent word conditions as well as in the pseudoword condition. The illiterate group performed least well in the incongruent condition and significantly better in the pseudoword condition compared to the neutral and incongruent word conditions and suggest that performance on phonological word length comparisons is dependent on literacy. In addition, the results show that the illiterate participants are able to perceive and process phonological length, albeit less well than the literate subjects, when no semantic interference is present. In conclusion, the present results confirm and extend the finding that illiterate subjects are biased towards semantic-conceptual-pragmatic types of cognitive processing.

Reading disability and hemispheric interaction on a lexical decision task

The assumptions tested were that the relative contribution of each hemisphere to reading alters with experience and that experience increases suppression of the simultaneous use of identical strategies by the non-dominant hemisphere. Males that were reading disabled and phonologically impaired, reading disabled and phonologically normal, or with no reading disability were presented familiar words, orthographically correct pseudowords, and orthographically incorrect non-words for lexical decision. Accuracy and response times in all groups showed a shift from no asymmetry in processing non-words to a stable left hemisphere advantage and clear suppression of the right hemisphere in processing words. In the pseudoword condition, accuracy scores were higher when both hemispheres were free to engage, especially in those with a reading disability and responses slowed in the phonologically impaired group but not the phonologically normal groups when the right hemisphere was disengaged. As familiar words typically invoke lexical processing by both hemispheres while pseudowords invoke lexical processing by the right and non-lexical processing by the left hemisphere, and as non-lexical processing is weak in the phonologically impaired, the results support the assumptions that were tested.

Conflicting strategies and hemispheric suppression in a lexical decision task

The research tests the prediction of the inhibitory-interaction hypothesis ( Wey, Cook, Landis, Regard, & Graves, 1993) that experience with a task accentuates the functional imbalance between the hemispheres. Right-handed males who were experienced readers were presented a letter string to the centre visual field for lexical decision. The string was or was not accompanied by a blinking light to the left or right visual field. It was predicted that asymmetry would be greatest for strings that spelled words, less for strings that were orthographically correct (pseudowords) and least for strings that were orthographically incorrect (nonwords) because efficient adult readers have more experience with letter strings that do than do not spell a word, and have more experience with orthographically correct than incorrect letter strings. The analysis of response times supported the prediction. Moreover, in the nonword and in early trials of the pseudoword conditions, response times were faster when one or other hemisphere was distracted than when both were engaged suggesting the hemispheres use strategies that conflict when suppression has not been accentuated by practice. As well, as the trials progressed in the pseudoword condition, asymmetry reversed before increasing suggesting that the hemispheres reduce conflict by competing for and then strengthening suppression.

Lexical decision of nonwords and pseudowords in humans: a positron emission tomography study

In this functional positron emission tomography study brain activations during an auditory lexical decision task with two experimental conditions were investigated. First, the subjects had to discriminate between real words and nonwords; second, real words varied with pseudowords. Comparing each of these tasks to an auditory control condition we found bilateral activation of the superior temporal and inferior frontal gyrus, lateralized to the left in the pseudoword condition. The comparison of the lexical decision tasks revealed higher rCBF during the pseudo-/real word decisions within BA 47, adjacent to Broca's area, and the anterior cingulate. The data support the notion that the lexical decision during a nonword task is mainly based on a phonological discrimination process, whereas a pseudoword task more strongly requires lexical access resulting in activation of BA 47.