Semantic priming with abstract and concrete words: differential asymmetry may be postlexical

We investigated whether abstract and concrete words would be differentially effective in priming lexical decisions to words presented to the right and left visual fields. Under low probability prime conditions, where priming is presumed to reflect a spreading activation process within the lexicon, equivalent priming was obtained in each VF for both abstract and concrete primes. However, when the same words were used in a high probability prime paradigm, abstract primes were much less effective in the LVF than in the RVF, while priming with concrete words did not differ across the visual fields. Since such priming may reflect a postlexical semantic integration stage, the results imply that hemisphere differences for processing abstract and concrete words may arise only after lexical access has occurred, when semantic information retrieved from the lexicon becomes available for subsequent processing.     

Semantic additivity and semantic inhibition: dissociable processes in the cerebral hemispheres?

We report the results of two visual half-field semantic priming experiments using a high proportion of related trials to examine hemisphere asymmetries for semantic processes beyond those attributable to automatic meaning activation. Contrary to previous investigations, we obtained inhibition for unrelated trials in both visual fields. However, priming was additive (being greater for words related via category membership and association than for either single dimension) only when words were presented to the RVF/left hemisphere. A third experiment, using centrally presented stimuli, implied that semantic additivity should be attributed to post-access meaning comparisons and inhibition to the generation of semantic expectancies. These results suggest (1) that inhibition and additivity are potentially dissociable "controlled" semantic processes and (2) that the left hemisphere predominates for meaning integration across successively presented words. The availability of finely tuned meaning integration processes in the left hemisphere may contribute to its superiority in language processing, despite right hemisphere competence for some semantic operations.     

Hemisphere dynamics in lexical access: automatic and controlled priming

Hemisphere differences in lexical processing may be due to asymmetry in the organization of lexical information, in procedures used to access the lexicon, or both. Six lateralized lexical decision experiments employed various types of priming to distinguish among these possibilities. In three controlled (high probability) priming experiments, prime words could be used as lexical access clues. Larger priming was obtained for orthographically similar stimuli (BEAK-BEAR) when presented to the left visual field (LVF). Controlled priming based on phonological relatedness (JUICE-MOOSE) was equally effective in either visual field (VF). Semantic similarity (INCH-YARD) produced larger priming for right visual field (RVF) stimuli. These results suggest that the hemispheres may utilize different information to achieve lexical access. Spread of activation through the lexicon was measured in complementary automatic (low probability) priming experiments. Priming was restricted to LVF stimuli for orthographically similar words, while priming for phonologically related stimuli was only obtained in the RVF. Automatic semantic priming was present bilaterally, but was larger in the LVF. These results imply hemisphere differences in lexical organization, with orthographic and semantic relationships available to the right hemisphere, and phonological and semantic relations available to the left hemisphere. Support was obtained for hemisphere asymmetries in both lexical organization and directed lexical processing.     

Automatic semantic priming in the left and right hemispheres

We investigated hemispheric differences and inter-hemispheric transfer of facilitation in automatic semantic priming, using prime-target pairs composed of words of the same category but not associated (e.g. skirt-glove), and a blank-target baseline condition. Reaction time and accuracy were measured at short (300 ms) intervals between prime and target onsets, using a go/no-go task to discriminate between word or non-word targets. Reaction times were facilitated more for target words presented in the right visual field (RVF) compared to the left visual field (LVF), and targets presented in RVF were primed in both visual fields, whereas targets presented in LVF were primed by primes in the LVF only. These results suggest that both hemispheres are capable of automatic priming at very short stimulus onset asymmetries (SOA), but cross-hemisphere priming occurs only in the left hemisphere.     

The effect of associative strength on priming in the cerebral hemispheres

Recent studies have suggested that semantic memory is more diffusely organized in the right hemisphere of the brain and that words directed to this hemisphere are more likely to activate meanings distantly related to the input. It is argued that this model of language processes predicts that variations in the associative strength of word pairs should give rise to different patterns of priming in each hemisphere. Specifically, the right hemisphere should exhibit relatively more facilitation than the left in response to weaker associative relationships, whereas the left hemisphere should exhibit relatively more facilitation than the right in the context of stronger relationships. This study varied the strength of the semantic association between prime and target in a divided visual field priming procedure. The results were unequivocal in demonstrating similar associative strength functions in each hemisphere, under conditions that encouraged either automatic or controlled processing. Visual field differences in absolute RTs to words and in magnitude of facilitation effects support the claim that the data collected in this study are veridical with respect to priming processes in the hemispheres. It is suggested that current models of hemispheric language processes require further refinement.     

Analogical priming via semantic relations

Research on semantic memory has often tacitly treated semantic relations as simple conduits for spreading activation between associated object concepts, rather than as integral components of semantic organization. Yet conceptual relations, and the role bindings they impose on the objects they relate, are central to such cognitive tasks as discourse comprehension, inference, problem solving, and analogical reasoning. The present study addresses the question of whether semantic relations and their bindings can influence access to semantic memory. The experiments investigated whether, and under what conditions, presenting a prime pair of words linked by 1 of 10 common semantic relations would facilitate processing of a target pair of words linked by the same relation. No effect was observed when participants merely read the prime; however, relational priming was observed under instructions to note and use the semantic relations. Participants were faster at making a lexical decision or naming a word on a related pair of target words when that pair was primed with an analogously related pair of words than when the prime pair consisted of either two unrelated words or two words linked by some other relation. This evidence of analogical priming suggests that under an appropriate strategic set, lexical decisions and naming latencies can be influenced by a process akin to analogical mapping.     

Interhemispheric communication via direct connections for alternative meanings of ambiguous words

A priming experiment was used to investigate Burgess and Simpson's (1988) claim that interhemispheric cooperation plays an essential role in the interpretation of ambiguous text. In doing so, the merits of two models of interhemispheric cooperation, the homotopic inhibition theory (Cook, 1986) and the direct connections model (Collins & Coney, 1998), were examined. Priming of alternative meanings of ambiguous words was measured using homographs and their dominant (e.g., BARK-DOG) and subordinate meanings (e.g., BARK-TREE) as related pairs in a lexical decision task, with normal university students as subjects. Stimulus pairs were temporally separated by stimulus onset asynchronies (SOAs) of 180 and 350 ms and were independently projected to the left or right visual fields (LVF or RVF). At the shorter SOA, priming was restricted to LVF-RVF presentations, with homograph primes directed to the LVF equally facilitating responses to RVF targets which were associated with their dominant and subordinate meanings. This suggests that within 180 ms, a homograph projected to the right hemisphere activates a range of alternative meanings in the left hemisphere. At an SOA of 350 ms, LVF-RVF priming was obtained along with RVF-LVF and RVF-RVF priming. Evidently at this stage of processing, an ambiguous word directed to either hemisphere activates a range of alternative meanings in the contralateral hemisphere, while RVF primes also activate subordinate, but not dominant meanings in the left hemisphere. A homograph directed to the LVF did not activate dominant or subordinate meanings within the right hemisphere at either SOA. Generally, ambiguous words directed to either hemisphere activated a more extensive array of meanings in the contralateral hemisphere than in the hemisphere to which the prime was directed. This confirms the importance of interhemispheric cooperation in generating alternate meanings of ambiguous words. Strong support was found for the direct connections model (Collins & Coney, 1998), but no support for the homotopic inhibition theory (Cook, 1986).     

Affective Priming Effects in the Left and Right Cerebral Hemispheres in Patients With Alzheimer's Disease

Alzheimer’s disease (AD) patients and control subjects were tested in an affective priming paradigm associated with an affective discrimination task. Two pictures, one affectively positive or affectively negative and the other neutral, were presented simultaneously in the right and in the left visual fields; the participants had to decide which of the two pictures was the most affectively positive or negative. The target pictures were preceded by a prime picture that was either affectively positive, affectively negative, or neutral. The principal result was the observation, in AD patients as well as in control subjects, of negative affective priming effects for targets presented in the right hemisphere, and of positive affective priming effects for targets presented in the left hemisphere. The presence of affective priming effects suggests that AD patients have no particular deficit in the automatic activation of emotional information; the fact that priming effects were also observed for targets presented in the left hemisphere showed that AD patients probably have no left hemisphere deficit in the automatic activation of emotional information. However, in AD patients, affective priming effects were significant with negative targets but not with positive targets, which could suggest that AD patients processed positive targets in a more semantic way than negative targets.     

Right Hemisphere Activation during Indirect Semantic Priming: Evidence from Event-Related Potentials

Healthy subjects performed a lexical decision task in a semantic priming paradigm while event-related potentials (ERPs) were recorded from 64 channels. Semantic distance between prime and target was varied by including directly, indirectly, and nonrelated word pairs. At centro-parietal electrodes an N400 to nonrelated pairs was elicited bilaterally which was sensitive only to direct, but not to indirect semantic priming. These N400 priming effects were mirrored by the RT data. At inferior fronto-temporal sites directly related words showed ERP priming effects over both hemispheres. However, indirectly related words only elicited ERP priming effects over the right hemisphere. These results support the hypothesis that the right hemisphere semantic system is involved in processing of remote semantic information.     

Examining the hemispheric distribution of semantic information using lateralised priming of familiar faces

The way in which the semantic information associated with people is organised in the brain is still unclear. Most evidence suggests either bilateral or left hemisphere lateralisation. In this paper we use a lateralised semantic priming paradigm to further examine this neuropsychological organisation. A clear semantic priming effect was found with greater priming occurring when semantically related prime faces were presented to the left visual field than when presented to the right visual field. Possible explanations for this finding are discussed in terms of the bilateral distribution of different classes of semantic information, a possible role of associative processes within semantic priming and interhemispheric transfer.     

Contextual modulation of N400 amplitude to lexically ambiguous words

Though much is known about the N400 component, an event-related EEG potential that is sensitive to semantic manipulations, it is unclear whether modulations of N400 amplitude reflect automatic processing, controlled processing, or both. We examined this issue using a semantic judgment task that manipulated local and global contextual cues. Word triplets (prime-noun-target, e.g., finance-bank-money) were sequentially presented on a computer screen (500 ms duration, 1000 ms stimulus onset asynchrony), in which the second word was a homograph. The first word (prime) created a neutral-, dominant-meaning- or subordinate-meaning-biased "global context," and the third word (target) created a dominant- or subordinate-biased "local context" that was either congruent or incongruent with the "global context" established by the first prime word. Participants were instructed to read all three words but to decide only whether the second and third words were semantically related. Event-related potentials (ERPs), specifically the N400, were recorded to the third terminal word. N400 amplitudes evoked by dominant meaning-related third words incongruent with the globally biased subordinate context (e.g., river-bridge-money) were significantly more negative than dominant endings in neutral contexts (e.g., taxi-bank-money), but not different from unrelated filler triplets. In addition, there was some indication that left hemisphere, temporal-parietal electrode sites were associated with greater N400 negativity for dominant targets in conflicting subordinate global contexts than homologous right hemisphere electrode sites, the latter of which showed significant activation to subordinate meanings in cooperating contexts. Thus, N400 amplitude was more affected by global than local context suggesting that controlled processes may take priority over automatic processes in modulating N400 amplitude, especially for left hemisphere electrode sites.     

Constraints on the range of context-independent priming from ambiguous words

The semantic priming technique was used to explore the semantic information activated by the contextually irrelevant meanings of ambiguous words in sentence contexts. The nature of the relationship between prime and target was systematically manipulated. Evidence of priming was obtained when the target was an approximate synonym of the prime (e.g., coach-bus), and when the target was a category coordinate of low similarity, but high category typicality (e.g., raincoat jumper, in Italian). No priming was obtained when the target was event related to the prime (coach-driver), nor when it was a highly similar category co-ordinate (raincoat overcoat, in Italian). However, in these latter cases, robust priming effects were obtained when the prime was presented out of context. The results are discussed in terms of the different kinds of semantic-retrieval operations that may be performed, depending upon whether or not the subjects attend to the meaning of the prime.     

The Micro-Category account of analogy

Here, we investigate how activation of mental representations of categories during analogical reasoning influences subsequent cognitive processing. Specifically, we present and test the central predictions of the "Micro-Category" account of analogy. This account emphasizes the role of categories in aligning terms for analogical mapping. In a semantic priming paradigm, a four-word analogy task was compared to two other four-word tasks. Stimuli were identical in all tasks; only the instructions given to participants differed. Participants were instructed to identify analogy relations, category relations, or conventionalized semantic relations in the four-word sets. After each four-word set, a single target word appeared and participants named this word aloud. Target words that referred to category relations in the preceding four-word sets were primed as strongly when participants identified analogies as when participants identified categories, suggesting that activation of category concepts plays an important role in analogical thinking. In addition, priming of category-referent words in the analogy and category tasks was significantly greater than priming of these words when participants identified conventionalized semantic relations. Since identical stimuli were used in all conditions, this finding indicates that it is the activation of category relations, distinct from any effect of basic semantic association, that causes analogical reasoning to prime category-referent words. We delineate how the "Micro-Category" account of analogy predicts these phenomena and unifies findings from diverse areas of research concerning analogical reasoning.     

Hemispheric differences in the time-course of semantic priming processes: evidence from event-related potentials (ERPs)

To investigate hemispheric differences in the timing of word priming, the modulation of event-related potentials by semantic word relationships was examined in each cerebral hemisphere. Primes and targets, either categorically (silk-wool) or associatively (needle-sewing) related, were presented to the left or right visual field in a go/no-go lexical decision task. The results revealed significant reaction-time and physiological differences in both visual fields only for associatively related word pairs, but an electrophysiological difference also tended to reach significance for categorically related words when presented in the left visual field. ERP waveforms showed a different time-course of associative priming effects according to the field of presentation. In the right visual field/left hemisphere, both N400 and Late Positive Component (LPC/P600) were modulated by semantic relatedness, while only a late effect was present in the left visual field/ right hemisphere.     

语义距离半球效应的ERP研究

以通过视觉通路呈现的汉语双字词为实验材料,操纵启动词与目标词的语义距离。在词汇决定实验中记录ERP,发现：（1）除N300外,P240亦对语义距离敏感,它可能是一种与语义加工有关的新的ERP成分;（2）P240在头皮中央偏左的部位较早出现,但在头皮右侧波幅较大;（3）N300和P240都不存在语义距离的半球效应,该结果没有证实右脑更专擅远距离语义加工的假设,表明使用汉语与使用拼音文字的脑机制存在差异。     

The influence of intention on masked priming: a study with semantic classification of words

Unconscious perception is commonly described as a phenomenon that is not under intentional control and relies on automatic processes. We challenge this view by arguing that some automatic processes may indeed be under intentional control, which is implemented in task-sets that define how the task is to be performed. In consequence, those prime attributes that are relevant to the task will be most effective. To investigate this hypothesis, we used a paradigm which has been shown to yield reliable short-lived priming in tasks based on semantic classification of words. This type of study uses fast, well practised classification responses, whereby responses to targets are much less accurate if prime and target belong to a different category than if they belong to the same category. In three experiments, we investigated whether the intention to classify the same words with respect to different semantic categories had a differential effect on priming. The results suggest that this was indeed the case: Priming varied with the task in all experiments. However, although participants reported not seeing the primes, they were able to classify the primes better than chance using the classification task they had used before with the targets. When a lexical task was used for discrimination in experiment 4, masked primes could however not be discriminated. Also, priming was as pronounced when the primes were visible as when they were invisible. The pattern of results suggests that participants had intentional control on prime processing, even if they reported not seeing the primes.     

With great expectations, can two "wrongs" prime a "right"?

The proportion of related prime-target pairs (relatedness proportion, RP) and prime-target stimulus onset asynchrony (SOA) was varied to determine the involvement of strategic priming mechanisms in the reduction in semantic priming that occurs when a target follows an unmasked prime that itself receives immediate repetition priming from a masked prime. At 300-ms and 1,200-ms SOAs, (a) strategic semantic priming was operating, in that priming from a nonrepeated prime increased as RP increased from .25 to .75, and (b) for both RPs, prime repetition reduced semantic priming. At a 167-ms SOA, (a) priming from a nonrepeated prime was unaffected by RP, suggesting that strategic priming was not operating, and (b) for both RPs, prime repetition did not reduce semantic priming. Because prime repetition did not reduce priming at the 167-ms SOA (when only spreading activation should have been mediating semantic priming), the reduction in semantic priming produced by prime repetition is not evidence against spreading activation automaticity. Possible mechanisms through which prime repetition reduces semantic priming are discussed.     

Subliminal words activate semantic categories (not automated motor responses)

Semantic priming by visually masked, unidentifiable (“subliminal”) words occurs robustly when the words appearing as masked primes have been classified earlier in practice as visible targets. It has been argued (Damian, 2001) that practice enables robust subliminal priming by automatizing learned associations between words and the specific motor responses used to classify them. Two experiments demonstrate that, instead, the associations formed in practice that underlie subliminal priming are between words and semantic categories. Visible words classified aspleasant or unpleasant in practice with one set of response key assignments functioned later as subliminal primes with appropriate valence, even when associations of keys with valences were reversed before the test. This result shows that subliminal priming involves unconscious categorization of the prime, rather than just the automatic activation of a practiced stimulus-response mapping.     

Right hemisphere language processing: Lateral difference with imageable and nonimageable ambiguous words

Influence of imageability on hemispheric processing difference is studied in a lexical decision task with semantic priming. Homographs and ambiguous words were biased according to the prime toward their low or high imageable meanings and unilaterally presented in the visual field. A right visual field (RVF) superiority was observed; it was nonsignificant for the high imageable (HI) meaning but significant for the low imageable (LI) meaning of the ambiguous words. Thus the results seem to favor a bilateral hemispheric representation of HI words and a unilateral left representation of LI words. Theoretical implications of the results are discussed to the various models of ambiguous word access processing.