Unrelated Prime Words Research Articles

Age-related dissociation of N400 effect and lexical priming

The use of contextual information is an important capability to facilitate language comprehension. This can be shown by studying behavioral and neurophysiological measures of accelerated word recognition when semantically or phonemically related information is provided in advance, resulting in accompanying attenuation of the respective event-related potential, i.e. the N400 effect. Against the background of age-dependent changes in a broad variety of lexical capacities, we aimed to study whether word priming is accomplished differently in elderly compared to young persons. 19 young (29.9 ± 5.6 years) and 15 older (69.0 ± 7.2 years) healthy adults participated in a primed lexical decision task that required the classification of target stimuli (words or pseudo-words) following related or unrelated prime words. We assessed reaction time, task accuracy and N400 responses. Acceleration of word recognition by semantic and phonemic priming was significant in both groups, but resulted in overall larger priming effects in the older participants. Compared with young adults, the older participants were slower and less accurate in responding to unrelated word-pairs. The expected N400 effect was smaller in older than young adults, particularly during phonemic word and pseudo-word priming, with a rather similar N400 amplitude reduction by semantic relatedness. The observed pattern of results is consistent with preserved or even enhanced lexical context sensitivity in older compared to young adults. This, however, appears to involve compensatory cognitive strategies with higher lexical processing costs during phonological processing in particular, suggested by a reduced N400 effect in the elderly.

Priming production: Neural evidence for enhanced automatic semantic activity preceding language production in schizophrenia.

IntroductionLexico-semantic disturbances are considered central to schizophrenia. Clinically, their clearest manifestation is in language production. However, most studies probing their underlying mechanisms have used comprehension or categorization tasks. Here, we probed automatic semantic activity prior to language production in schizophrenia using event-related potentials (ERPs).Methods19 people with schizophrenia and 16 demographically-matched healthy controls named target pictures that were very quickly preceded by masked prime words. To probe automatic semantic activity prior to production, we measured the N400 ERP component evoked by these targets. To determine the origin of any automatic semantic abnormalities, we manipulated the type of relationship between prime and target such that they overlapped in (a) their semantic features (semantically related, e.g. “cake” preceding a < picture of a pie >, (b) their initial phonemes (phonemically related, e.g. “stomach” preceding a < picture of a starfish >), or (c) both their semantic features and their orthographic/phonological word form (identity related, e.g. “socks” preceding a < picture of socks >). For each of these three types of relationship, the same targets were paired with unrelated prime words (counterbalanced across lists). We contrasted ERPs and naming times to each type of related target with its corresponding unrelated target.ResultsPeople with schizophrenia showed abnormal N400 modulation prior to naming identity related (versus unrelated) targets: whereas healthy control participants produced a smaller amplitude N400 to identity related than unrelated targets, patients showed the opposite pattern, producing a larger N400 to identity related than unrelated targets. This abnormality was specific to the identity related targets. Just like healthy control participants, people with schizophrenia produced a smaller N400 to semantically related than to unrelated targets, and showed no difference in the N400 evoked by phonemically related and unrelated targets. There were no differences between the two groups in the pattern of naming times across conditions.ConclusionPeople with schizophrenia can show abnormal neural activity associated with automatic semantic processing prior to language production. The specificity of this abnormality to the identity related targets suggests that that, rather than arising from abnormalities of either semantic features or lexical form alone, it may stem from disruptions of mappings (connections) between the meaning of words and their form.

Lexical–semantic priming effects during infancy

When and how do infants develop a semantic system of words that are related to each other? We investigated word-word associations in early lexical development using an adaptation of the inter-modal preferential looking task where word pairs (as opposed to single target words) were used to direct infants' attention towards a target picture. Two words (prime and target) were presented in quick succession after which infants were presented with a picture pair (target and distracter). Prime-target word pairs were either semantically and associatively related or unrelated; the targets were either named or unnamed. Experiment 1 demonstrated a lexical-semantic priming effect for 21-month olds but not for 18-month olds: unrelated prime words interfered with linguistic target identification for 21-month olds. Follow-up experiments confirmed the interfering effects of unrelated prime words and identified the existence of repetition priming effects as young as 18 months of age. The results of these experiments indicate that infants have begun to develop semantic-associative links between lexical items as early as 21 months of age.

Morphological priming in overt language production: Electrophysiological evidence from Dutch

The present study investigated morphological priming in Dutch and its time course in overt speech production using a long-lag priming paradigm. Prime words were compounds that were morphologically related to a picture name (e.g. the word jaszak, ‘coat pocket’ was used for a picture of a coat; Dutch jas) or form-related monomorphemic words (e.g. jasmijn, ‘jasmine’). The morphologically related compounds could be semantically transparent (e.g. eksternest, ‘magpie nest’) or opaque (e.g. eksteroog, lit. ‘magpie eye’, ‘corn’, for a picture of a magpie, Dutch ekster). Behavioral and event-related potential (ERP) data were collected in two sessions. The production of morphologically related and complex words facilitated subsequent picture naming and elicited a reduced N400 compared with unrelated prime words. The effects did not differ for transparent and opaque relations. Mere form overlap between a prime word and a target picture name did not affect picture naming. These results extend previous findings from German to another language and demonstrate the feasibility of measuring cognitive ERP components during overt speech. Furthermore, the results suggest that morphological priming in language production cannot be reduced to semantic and phonological processing. The time course of these priming effects as reflected in the ERP measure is in accordance with a meta-analytic temporal estimate of morphological encoding in speaking [Indefrey, P., & Levelt, W.J.M. (2004). The spatial and temporal signatures of word production components. Cognition, 92, 101–144.] suggesting that morphological relations are encoded at the word form level.

Cortical activation during a semantic priming lexical decision task as revealed by event-related fMRI

Previous studies using event-related brain potentials (ERPs) have shown an increase in the amplitude of the N400 component m response to words or pseudowords preceded by unrelated prime words than to words preceded by semantically related prime words (e.g., Holcomb, 1988). We report here an fMRI study aimed at identifying the cortical regions underlying this effect. More generally, the goal of this study was to localize the neuroanatomical substrates of semantic information processing.

Picture naming: identical priming and word frequency interact

In picture naming, the effects of identical or repetition priming and language frequency are most probably localized at the same processing level: the retrieval of the phonological word form of the picture's name. This conclusion is supported by the observation that repetition priming is larger for pictures with low-frequency names than for pictures with high-frequency names. However, in two recent studies in which the prime word was masked, identical priming and word frequency combined additively. The cause of this unexpected finding was investigated in four experiments. Experiments 1 and 2 showed that the use of the masked-priming technique is not the underlying factor. Instead, Experiments 3 and 4 revealed that the discrepancy most probably resulted from the use of unrelated prime words as the baseline from which identical priming was measured. When neutral (non word) primes were used as the baseline, word frequency and identical priming showed the expected interaction.

Development of semantic and phonological priming in a shallow orthography.

These studies examined whether the unusual accessibility of phonological information from written Korean affects the word recognition processes of children learning to read it. In Experiment 1, 2nd- and 6th-grade Korean children named target words that were preceded by related or unrelated prime words. Priming was found for 6th but not 2nd graders-the opposite of the pattern seen in children reading English. Experiment 2 examined phonological priming in 3rd and 6th graders. Related primes were pseudohomophones of the targets. Younger children tended to show greater priming than did older ones. The results suggest strong reliance on phonological information by children learning to read a script from which such information is easily accessed.

The Processing Nature of the N400: Evidence from Masked Priming

Abstract The N400 is an endogenous event-related brain potential (ERP) that is sensitive to semantic processes during language comprehension. The general question we address in this paper is which aspects of the comprehension process are manifest in the N400. The focus is on the sensitivity of the N400 to the automatic process of lexical access, or to the controlled process of lexical integration. The former process is the reflex-like and effortless behavior of computing a form representation of the linguistic signal, and of mapping this representation onto corresponding entries in the mental lexicon. The latter process concerns the integration of a spoken or written word into a higher-order meaning representation of the context within which it occurs. ERPs and reaction times (RTs) were acquired to target words preceded by semantically related and unrelated prime words. The semantic relationship between a prime and its target has been shown to modulate the amplitude of the N400 to the target. This modulation can arise from lexical access processes, reflecting the automatic spread of activation between words related in meaning in the mental lexicon. Alternatively, the N400 effect can arise from lexical integration processes, reflecting the relative ease of meaning integration between the prime and the target. To assess the impact of automatic lexical access processes on the N400, we compared the effect of masked and unmasked presentations of a prime on the N400 to a following target. Masking prevents perceptual identification, and as such it is claimed to rule out effects from controlled processes. It therefore enables a stringent test of the possible impact of automatic lexical access processes on the N400. The RT study showed a significant semantic priming effect under both unmasked and masked presentations of the prime. The result for masked priming reflects the effect of automatic spreading of activation during the lexical access process. The ERP study showed a significant N400 effect for the unmasked presentation condition, but no such effect for the masked presentation condition. This indicates that the N400 is not a manifestation of lexical access processes, but reflects aspects of semantic integration processes.

Priming word recognition with orthographic neighbors: Effects of relative prime-target frequency.

Four lexical decision experiments were performed with an orthographic priming paradigm in which test words were preceded by orthographically related or unrelated prime words. When prime words were presented for 350 ms without a mask, it was observed that primes that are lower frequency orthographic neighbors of the target interfered with target processing relative to an unrelated condition. When primes were higher frequency neighbors of the target, no interference or facilitation was observed. On the other hand, with briefly presented masked primes, interference was observed with higher frequency prime words. Finally, facilitatory effects in masked repetition priming were obtained with both high- and low-frequency prime-target pairs. The results are interpreted in terms of activation and selection processes operating in visual word recognition.