Primed-lexical decision: The effect of varying the stimulus-onset asynchrony of prime and target

Lexical decisions to word targets are usually faster when they are preceded by associatively related word primes than when they follow a neutral prime. Also; it has been shown that, under certain circumstances, lexical decisions to words preceded by unassociated word primes are slower than those to words following a neutral prime. The present study explores the influence of the stimulus-onset asynchrony (SOA) of prime and target on these priming effects. Eleven SOAs were investigated ranging from 100 msec to 1240 msec. The facilitatory effect of related primes was reliable in all SOA conditions. The inhibitory effect of unrelated primes was reliable in all but one SOA condition. Furthermore, it was found that, up to the longest SOA, facilitation increases with SOA, whereas inhibition remains virtually constant. In the longest SOA condition both facilitation and inhibition decrease. Yet another finding was that pseudowords following non-neutral primes were processed faster than those preceded by neutral primes, except with the two shortest SOAs. It appears that the SOA data cannot be satisfactorily interpreted in terms of actual priming processes, that is, processes that prepare subsequent word recognition, and that some experimental artifacts may partly have been responsible for the observed pattern of results.     

Priming nouns and verbs: differential influences of semantic and grammatical cues in the two cerebral hemispheres

The current experiment investigated how sentential form-class expectancies influenced lexical-semantic priming within each hemisphere. Sentences were presented that led readers to expect a noun or a verb and the sentence-final target word was presented to one visual field/hemisphere for a lexical decision response. Noun and verb targets in the semantically related condition were compared to an unrelated prime condition, which also predicted part of speech but did not contain any lexical-semantic associates of the target word. The semantic priming effect was strongly modulated by form-class expectancy for RVF/LH targets, for both nouns and verbs. In the LVF/RH, semantic priming was obtained in all conditions, regardless of whether the form-class expectancy was violated. However, the nouns that were preceded by a noun-predicting sentence showed an extremely high priming value in the LVF/RH, suggesting that the RH may have some sensitivity to grammatical predictions for nouns. Comparisons of LVF/RH priming to calculations derived from the LSA model of language representation, which does not utilize word order, suggested that the RH might derive message-level meaning primarily from lexical-semantic relatedness.     

Priming of emotion recognition

Four experiments investigated priming of emotion recognition using a range of emotional stimuli, including facial expressions, words, pictures, and nonverbal sounds. In each experiment, a prime-target paradigm was used with related, neutral, and unrelated pairs. In Experiment 1, facial expression primes preceded word targets in an emotion classification task. A pattern of priming of emotional word targets by related primes with no inhibition of unrelated primes was found. Experiment 2 reversed these primes and targets and found the same pattern of results, demonstrating bidirectional priming between facial expressions and words. Experiment 2 also found priming of facial expression targets by picture primes. Experiment 3 demonstrated that priming occurs not just between pairs of stimuli that have a high co-occurrence in the environment (for example, nonverbal sounds and facial expressions), but with stimuli that co-occur less frequently and are linked mainly by their emotional category (for example, nonverbal sounds and printed words). This shows the importance of the prime and target sharing a common emotional category, rather than their previous co-occurrence. Experiment 4 extended the findings by showing that there are category-based effects as well as valence effects in emotional priming, supporting a categorical view of emotion recognition.     

Locus of inhibition effects in the priming of lexical decisions: pre- or postlexical access?

The lexical decision task has been employed to investigate the effects of semantic context on word recognition. A frequent finding from the task is that “word” responses are slower when the target is preceded by an unrelated word than when it is preceded by a neutral stimulus. This inhibition effect has been interpreted as indicating that the unrelated prime interferes with word-recognition processes operating on the target. In three experiments, the effects of unrelated primes were compared for a lexical decision and word naming task. Although large inhibition effects were found for the lexical decision task in all experiments, no inhibition effects were observed for the naming task. The results are interpreted as demonstrating that inhibition effects in the lexical decision task are not on recognition processes; rather they are located at processes operating after recognition of the target has occurred.     

On obtaining episodic priming in a lexical decision task following paired-associate learning

In four experiments, subjects made lexical (word-nonword) decisions to target letter strings after studying paired associates. In this lexical decision test, word targets previously studied as response terms in the paired associates were preceded at a 150-ms and/or 950-ms stimulus onset asynchrony (SOA) by one of various subsets of the following six types of primes: a neutral (XXX or ready) prime, a semantically unrelated word prime episodically related to the target through its having been previously studied in the same pair, a semantically related word prime previously studied in a pair with some other unrelated word, a semantically unrelated word prime previously studied in a pair with some other unrelated word, a nonstudied semantically related word prime, and a nonstudied semantically unrelated word prime. At the 950-ms SOA, facilitation of lexical decisions produced by the episodically related primes was greater in test lists in which there were no 150-ms SOA trials intermixed, no previously studied semantically related primes, and no studied nonword targets. At the 150-ms SOA, facilitation from episodic priming was greater in test lists in which there were no semantically related primes and all studied word targets and no studied nonword targets. Facilitation effects from semantically related primes were small in magnitude and occurred inconsistently. Discussion focused on the implications these results have for the episodic-semantic memory distinction and the automaticity of episodic and semantic priming effects.     

Repetition priming reveals hemispheric differences in compound word processing

The left (LH) and right (RH) hemispheres are thought to implement different mechanisms for visual word recognition; the LH’s parallel encoding strategy is more efficient than the RH’s serial, letter-by-letter analysis. Here we examine differences in hemispheric language processing strategy by investigating repetition priming of compound words (e.g. buttercup) and their constituents (e.g. butter, cup). Eighty-eight right-handed participants (29 M, 59 F) completed a lexical decision experiment in which centrally-presented compounds primed related (whole compound, first constituent, second constituent) and unrelated targets presented laterally to the left or right visual field; participants made button-press word/nonword decisions. Consistent with the LH parallel/RH serial distinction, repetition priming prompted an RH advantage for first constituents, whereas the LH performed equally efficiently in response to both first and second constituents. These data thus highlight differences in the hemispheres’ language processing strategies, offering new evidence supporting a relative parallel/serial distinction in LH/RH visual word recognition.     

Right hemisphere sensitivity to novel metaphoric relations: application of the signal detection theory

The present study used the signal detection theory to test the hypothesis that the right hemisphere (RH) is more sensitive than the left hemisphere (LH) to the distant semantic relations in novel metaphoric expressions. In two divided visual field experiments, sensitivity (d') and criterion (beta) were calculated for responses to different types of word pairs. In the first experiment, subjects were presented with unfamiliar two-word novel metaphoric expressions ("signal") and unrelated word-pairs ("noise"). In the second experiment, literal expressions ("signal") and unrelated word pairs ("noise") were presented. In line with the Coarse Semantic Coding Theory [Beeman, M. (1998). Coarse semantic coding and discourse comprehension. In: M. Beeman & C. Chiarello (Eds.). Right hemisphere language comprehension: Perspectives from cognitive neuroscience. Mahwah, NJ: Erlbaum, pp. 255-284.] as well as with the Graded Salience Hypothesis [Giora, R. (2003). On our mind: Salience, context and figurative language. New York: Oxford University Press.], the findings suggest that the RH is more sensitive than the LH to unfamiliar metaphoric relations. Furthermore, this RH advantage in processing distant semantic relations did not extend to familiar semantic relations.     

The representation of discourse in the two hemispheres: an individual differences investigation

Two experiments were conducted to investigate discourse representation in the two cerebral hemispheres as a function of reading skill. We used a lateralized visual-field procedure to compare left hemisphere (LH) and right hemisphere (RH) sensitivity to different discourse relations in readers with varying skill levels. In Experiment 1, we investigated two levels of discourse representation in memory: (a) the propositional representation and (b) the discourse model. We found that all readers were sensitive to propositional relations in the LH. In contrast, sensitivity to propositional relations in the RH increased as a function of reading skill. In addition, reading skill was positively related to topic relations in the LH, whereas it was negatively in the RH. In Experiment 2, we investigated propositional relations of different distances and again found that all readers were sensitive to propositional relations in the LH, whereas sensitivity to propositional relations in the RH was negatively related to reading skill. In general, reading skill appears to be associated with left-lateralized discourse representations.     

Strategic reliance on phonological mediation in lexical access

The present study investigated strategic variation in reliance on phonological mediation in visual word recognition. In Experiment 1, semantically related or unrelated word primes preceded word, pseudohomophone (e.g.,trane), or nonpseudohomophone (e.g.,trank) targets in a lexical decision task. Semantic priming effects were found for words, and response latencies to pseudohomophones were longer in related than in unrelated prime conditions. In Experiment 2, related or unrelated word primes preceded word or pseudohomophone targets. A relatedness effect was found for words, although it was significant at a 600-msec prime-target stimulus onset asynchrony (SOA) and not at a 200-msec SOA. There was no relatedness effect for pseudohomophones. Experiment 3 was a replication of Experiment 2, except that pseudohomophones were replaced by nonpseudohomophonic orthographic controls. Facilitation effects for related target words were greater in Experiment 3 than in Experiment 2. The results reflect apparent variations in the expectation that a related prime reliably indicates that a target is a word. Although reliance on phonological mediation might be strategically contingent, there could be a brief time period in which phonologically mediated lexical access occurs automatically. Whether phonological information is maintained or suppressed subsequently depends on its overall usefulness for the task.     

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.     

The influence of context on lexical decision times for emotionally aversive words

Forty-eight undergraduates made lexical decisions about emotionally aversive and nonemotional words. Emotionally aversive target words were preceded either by an emotionally aversive prime word, a nonemotional but semantically related prime or a nonemotional and semantically unrelated prime. Nonemotional targets were preceded by nonemotional primes which were either semantically related to targets, unrelated, or neutral (strings of Xs). Primes were presented for 50 ms to one group of 16 participants, 500 ms to a second group and 1250 ms to a third group. Measurement of lexical decision time showed significant semantic primary effects for nonemotional targets, and these were not influenced by prime duration. Priming effects for emotionally aversive targets due both to emotional and nonemotional relatedness of primes and targets were also found and these effects were not influenced by prime duration. The results are considered to be consistent with Bower’s (1981) associative network theory of memory, and possible clinical implications for explaining spontaneous panic attacks and the incubation of anxiety are discussed.     

Form-based priming in spoken word recognition: the roles of competition and bias.

Phonological priming of spoken words refers to improved recognition of targets preceded by primes that share at least one of their constituent phonemes (e.g., BULL-BEER). Phonetic priming refers to reduced recognition of targets preceded by primes that share no phonemes with targets but are phonetically similar to targets (e.g., BULL-VEER). Five experiments were conducted to investigate the role of bias in phonological priming. Performance was compared across conditions of phonological and phonetic priming under a variety of procedural manipulations. Ss in phonological priming conditions systematically modified their responses on unrelated priming trials in perceptual identification, and they were slower and more errorful on unrelated trials in lexical decision than were Ss in phonetic priming conditions. Phonetic and phonological priming effects display different time courses and also different interactions with changes in proportion of related priming trials. Phonological priming involves bias; phonetic priming appears to reflect basic properties of activation and competition in spoken word recognition.     

Mixing metaphors in the cerebral hemispheres: what happens when careers collide?

Are processes of figurative comparison and figurative categorization different? An experiment combining alternative-sense and matched-sense metaphor priming with a divided visual field assessment technique sought to isolate processes of comparison and categorization in the 2 cerebral hemispheres. For target metaphors presented in the right visual field/left cerebral hemisphere (RVF/LH), only matched-sense primes were facilitative. Literal primes and alternative-sense primes had no effect on comprehension time compared to the unprimed baseline. The effects of matched-sense primes were additive with the rated conventionality of the targets. For target metaphors presented to the left visual field/right cerebral hemisphere (LVF/RH), matched-sense primes were again additively facilitative. However, alternative-sense primes, though facilitative overall, seemed to eliminate the preexisting advantages of conventional target metaphor senses in the LVF/RH in favor of metaphoric senses similar to those of the primes. These findings are consistent with tightly controlled categorical coding in the LH and coarse, flexible, context-dependent coding in the RH.     

Primed lexical decision: Combined effects of the proportion of related prime-target pairs and the stimulus-onset asynchrony of prime and target

Lexical decisions to word targets preceded by associatively related word primes are generally faster than those to words following neutral primes, whereas, under certain circumstances, lexical decisions to words preceded by unassociated word primes are slower than those to words following neutral primes. An experiment is reported that investigates the influence of the proportion of related prime-target pairs in the set of materials and of the stimulus-onset asynchrony (SOA) of prime and target on these associative priming effects. Four levels of proportion and three levels of SOA are systematically varied. Both variables are found to affect the size of the associative priming effects. Furthermore, the data suggest interdependence between them. The magnitude of priming only varies with SOA if the proportion of related pairs is relatively large. In contrast, the amount of priming varies with proportion under all SOA conditions. The data are interpreted primarily in terms of two contextual processes, viz., “prime-induced attentional processing” and “post-lexical coherence checking”.     

Exploring the additive effects of stimulus quality and word frequency: The influence of local and list-wide prime relatedness

Stimulus quality and word frequency produce additive effects in lexical decision performance, whereas the semantic priming effect interacts with both stimulus quality and word frequency effects. This pattern places important constraints on models of visual word recognition. In Experiment 1, all three variables were investigated within a single speeded pronunciation study. The results indicated that the joint effects of stimulus quality and word frequency were dependent upon prime relatedness. In particular, an additive effect of stimulus quality and word frequency was found after related primes, and an interactive effect was found after unrelated primes. It was hypothesized that this pattern reflects an adaptive reliance on related prime information within the experimental context. In Experiment 2, related primes were eliminated from the list, and the interactive effects of stimulus quality and word frequency found following unrelated primes in Experiment 1 reverted to additive effects for the same unrelated prime conditions. The results are supportive of a flexible lexical processor that adapts to both local prime information and global list-wide context.     

Preserved Semantic Priming Effect in Alexia

BH, a left-handed patient with alexia and nonfluent aphasia, was presented with a lexical-decision task in which words and pronounceable pseudowords were preceded by semantically related or unrelated picture primes (Experiment 1). In Experiment 2, BH was given an explicit reading task using the word lists from Experiment 1. Performance on Experiment 2 disclosed severe reading deficits in both oral reading and semantic matching of the words to pictures. However, in Experiment 1, BH demonstrated a significant semantic priming effect, responding more accurately and more quickly to words preceded by related primes than by unrelated primes. The present results suggest that even in a patient with severe alexia, implicit access to semantic information can be preserved in the absence of explicit identification. The possibility of categorical gradient in implicit activation (living vs. nonliving) in BH was also discussed, which, however, needs to be clarified in the further investigation.