Derived stimulus relations, semantic priming, and event-related potentials: testing a behavioral theory of semantic networks

Derived equivalence relations, it has been argued, provide a behavioral model of semantic or symbolic meaning in natural language, and thus equivalence relations should possess properties that are typically associated with semantic relations. The present study sought to test this basic postulate using semantic priming. Across three experiments, participants were trained and tested in two 4-member equivalence relations using word-like nonsense words. Participants also were exposed to a single- or two-word lexical decision task, and both direct (Experiment 1) and mediated (Experiments 2 and 3) priming effects for reaction times and event-related potentials were observed within but not across equivalence relations. The findings support the argument that derived equivalence relations provides a useful preliminary model of semantic relations.     

Physiological evidence that a masked unrelated intervening item disrupts semantic priming: implications for theories of semantic representation and retrieval models of semantic priming

Event-related potentials were recorded in a paradigm where an unrelated word was interposed between two related words. In one condition, the intervening item was masked and in another condition it was not. The N400 component indicated that priming of the related word was disrupted by the intervening item whether it was masked or not. The data are interpreted to be inconsistent with retrieval models of priming.     

Constraints on semantic priming in reading: A fixation time analysis

In Experiment 1, subjects read sentences containing a category name or a neutral prime that was followed by a target exemplar that varied in typicality. Fixation time on the target exemplar was the measure of processing difficulty. The category name facilitated processing for both high- and low-typicality exemplars. Unexpectedly, high-typicality exemplars were processed more quickly than low-typicality exemplars in both primed and unprimed conditions. Experiment 2 extended the priming effect to primary associates. Most importantly, the priming effect was influenced by the syntactic structure of the stimulus sentence. When both the prime and the associated target word were in the same clause, semantic priming occurred, but when the prime and target were in different clauses, no associative facilitation was observed. These results were interpreted as supporting a clausal processing hypothesis based on an autonomous modular view of the language processing system. Furthermore, the results were consistent with direct control models of eye movements, which claim that fixation duration reflects the timing of processing related to the word currently under fixation.     

Types of semantic category and stimulus modality in procedural learning: implications for models of semantic memory

The present work attempts to determine whether procedural learning of a semantic categorisation task is influenced by the type of semantic category of the stimuli (biological and non-biological elements). It is also an attempt to determine the effect of the stimulus presentation modality on the categorisation task. A semantic categorisation task (4 series of 40 stimuli) was administered to 256 participants (128 classifying pictures, and 128 classifying words). Biological categories were responded to faster than non-biological ones although there were no significant differences between the interaction of the category type and the stimulus presentation modality. Reaction times progressively decreased with practice. However, the initial differences disappeared when subjects were trained. The way that current models account for these investigation findings is discussed. In addition, it is suggested that there is an attentional bias in favor of biological elements, which disappears when presumably less relevant elements become more relevant as a function of the task characteristics.     

Repetition priming within and between languages in semantic classification of concrete and abstract words

Although concrete nouns are generally agreed to have shared core conceptual representations across languages in bilinguals, it has been proposed that abstract nouns have separate representations or share fewer semantic components. Conceptual repetition priming methodology was used to evaluate whether translation equivalents of abstract nouns have shared conceptual representations and compare the degree of conceptual overlap for concrete and abstract nouns. Here 72 Spanish-English bilinguals made concrete-abstract decisions on English and Spanish nouns. Both concrete and abstract nouns elicited substantial between-language priming and these effects were of equivalent size, indicating that translation equivalents of both concrete and abstract nouns have shared conceptual representations and that abstract words do not share fewer components. The between-language priming effects and their attenuation relative to within-language priming indicate that the within-language effect is based on facilitation of both word comprehension and semantic decision processes.     

Repetition priming within and between languages in semantic classification of concrete and abstract words

Although concrete nouns are generally agreed to have shared core conceptual representations across languages in bilinguals, it has been proposed that abstract nouns have separate representations or share fewer semantic components. Conceptual repetition priming methodology was used to evaluate whether translation equivalents of abstract nouns have shared conceptual representations and compare the degree of conceptual overlap for concrete and abstract nouns. Here 72 Spanish–English bilinguals made concrete–abstract decisions on English and Spanish nouns. Both concrete and abstract nouns elicited substantial between-language priming and these effects were of equivalent size, indicating that translation equivalents of both concrete and abstract nouns have shared conceptual representations and that abstract words do not share fewer components. The between-language priming effects and their attenuation relative to within-language priming indicate that the within-language effect is based on facilitation of both word comprehension and semantic decision processes.     

Repetition priming in visual search: Episodic retrieval,not feature priming

Previous research has shown that when the targets of successive visual searches have features in common, response times are shorter. However, the nature of the representation underlying this priming and how priming is affected by the task remain uncertain. In four experiments, subjects searched for an odd-sized target and reported its orientation. The color of the items was irrelevant to the task. When target size was repeated from the previous trial, repetition of target color speeded the response. However, when target size was different from that in the previous trial, repetition of target color slowed responses, rather than speeding them. Our results suggest that these priming phenomena reflect the same automatic mechanism as the priming of pop-out reported by Maljkovic and Nakayama (1994). However, the crossover interaction between repetition of one feature and another rules out Maljkovic and Nakayama's (1994) theory of independent potentiation of distinct feature representations. Instead, we suggest that the priming pattern results from contact with an episodic memory representation of the previous trial.     

Repetition and form priming interact with neighborhood density at a brief stimulus onset asynchrony

The relationships between repetition- and form-priming effects and neighborhood density were analyzed in two masked priming experiments with the lexical decision task. Given that form-priming effects appear to be influenced by a word’s orthographic neighborhood, it is theoretically important to find out whether repetition priming also differs as a function of the word’s orthographic neighborhood. Within an activation framework, repetition- and form-priming effects are just quantitatively different phenomena, whereas the two effects are qualitatively different in a serial-ordered model of lexical access (theentry-opening model). The results show that repetition- and form-priming effects were stronger forhermit words than for words with many neighbors. These results pose some problems for both activation and serial-ordered models. The implications of these results for determining how neighbors affect the identification of a word are discussed.     

Repetition priming of words, pseudowords, and nonwords

In 5 experiments, the authors assessed repetition priming for words, pseudowords, and nonwords using a task that combines an implicit perceptual fluency measure and a recognition memory assessment for each list item. Words and pseudowords generated a consistently strong repetition effect even when there was a failure to recognize the stimulus. In 2 of the experiments, the repetition effect for nonwords was reliably above chance even when there was a failure to recognize the stimulus. The authors propose a parallel distributed processing (PDP) model based on the work of J. McClelland and D. Rumelhart (1985) as a way to understand the mechanisms potentially responsible for the pattern of findings. Although the error-driven nature of learning in the model results in a poor fit to the nonword priming data, this is not endemic to all PDP models. Using a model based on Hebbian learning, the authors instantiate a property that they believe is characteristic of implicit memory--that learning is primarily based on the strengthening of connections between units that become active during the processing of a stimulus. This model provides a far more satisfactory account of the data than does the error-driven model.     

Phonological and semantic priming: Evidence for task-independent effects

The questions asked in the present experiments concern the generality of semantic and phonological priming effects: Do these effects arise automatically regardless of target task, or are these effects restricted to target tasks that specifically require the retrieval of the primed information? In Experiment 1, subjects produced faster color matching times on targets preceded by a masked rhyming prime than on targets preceded by an orthographic control or an unrelated prime. This result suggests that automatic priming effects on the basis of phonological similarity can be obtained even when the target task does not make use of phonological information. This claim was reinforced in Experiment 2 in which a rhyme priming effect and a semantic priming effect were found in a semantic categorization task. In Experiment 3, the target task was phonological (rhyme detection), and, again, both phonological and semantic priming effects were observed. Finally, in Experiments 4 and 5, in a replication and an extension of Experiment 1, phonological and semantic priming effects were found in a color matching task, a task involving neither phonological nor semantic processing. These results are most straightforwardly interpreted by assuming that both semantic and phonological priming effects are, at least in part, due to automatic activation of memorial representations.     

Phonological, semantic, and repetition priming with homophones

The current study investigated semantic, repetition, and phonological priming using heterographic homonyms (homophones) as stimuli in a lexical decision task. As in previous research, reliable semantic priming and repetition effects were found. In addition, the statistical additivity of these two effects was replicated using homophones as stimuli. Using homophones, a reliable phonological priming effect was found when 10-16 intervening trials were used. This effect was also statistically independent of semantic priming indicating the independence of the mechanisms responsible for semantic and phonological priming. The magnitude of the phonological priming effect was also significantly less than the magnitude of the repetition effect. This difference in effect magnitude was taken to indicate that the repetition of phonological information is not a primary contributor to the repetition effect.     

Morphological priming: Dissociation of phonological, semantic, and morphological factors

Previous experiments based on a masked-priming paradigm revealed robust morphological priming effects induced by two derivational morphemes in Hebrew: the root and the verbal pattern. However, considering the special characteristics of the masked-priming paradigm, the possible contributions of phonological and/or semantic factors to these morphological effects could not be firmly assessed. In the present study, the role of these factors in morphological priming was examined, using cross-modal presentation. Experiment 1 revealed that priming between morphologically related words in Hebrew is determined by higher level linguistic characteristics and cannot be reduced to phonological overlap. Experiment 2 confirmed that morphological priming occurs in Hebrew even when primes and targets are not semantically related but, nevertheless, increases with semantic similarity. The results support the claim that morphological priming cannot be accounted for by considering semantic and phonological factors alone, and they exemplify the potential of using both masked and cross-modal priming to examine morphological processing.     

Investigating semantic memory impairments: The contribution of semantic priming

Abstract

The semantic priming task is a valuable tool in the investigation of semantic memory impairments in patients with acquired disorders of language. This is because priming performance reflects automatic or implicit access to semantic information, unlike most other tests of semantic knowledge, which rely on explicit, voluntary access. Priming results are important for two main reasons: First, normal priming results may be observed in patients who perform poorly on other semantic memory tests, enabling us to distinguish between loss of, or damage to, information in semantic memory, and voluntary access to that information. Second, we can investigate the detailed pattern of loss and preservation of different types of semantic information, by charting the priming effects for different kinds of words, and different kinds of semantic relations between primes and targets.

We discuss the use of the priming task in this context, and address some of the theoretical and methodological criticisms that have been raised in connection with use of the priming task to address these issues. We then describe two recent studies in which we have employed semantic priming tasks, along with other more traditional methods, to investigate specific questions about the semantic memory deficits of three patients.     

The distribution of fixation durations during reading: effects of stimulus quality

Participants' eye movements were recorded as they read single sentences presented normally, presented entirely in faint text, or presented normally except for a single faint word. Fixations were longer when the entire sentence was faint than when the sentence was presented normally. In addition, fixations were much longer on a single faint word embedded in normal text, compared to when the entire sentence was faint. The primary aim of the study was to examine the influence of stimulus quality on the distribution of fixation durations. Ex-Gaussian fitting revealed that stimulus quality affected the mean of the Normal component, but in contrast to results from single-word tasks (Plourde & Besner, 1997), stimulus quality did not affect the exponential component, regardless of whether one or all words were faint. The results also contrast with the finding (Staub, White, Drieghe, Hollway, & Rayner, 2010) that the word frequency effect on fixation durations is an effect on both of the critical distributional parameters. These findings are argued to have implications for the interpretation of the role of stimulus quality in word recognition, and for models of eye movement control in reading.     

Repetition priming within and between the two cerebral hemispheres

Two experiments explored repetition priming benefits in the left and right cerebral hemispheres. In both experiments, a lateralized lexical decision task was employed using repeated target stimuli. In the first experiment, all targets were repeated in the same visual field, and in the second experiment the visual field of presentation was switched following repetition. Both experiments demonstrated hemispheric specialization for the task (a RVF advantage for word identification) and hemispheric interaction for word processing (lexicality priming from contralateral distracters). In the first experiment, words were identified more quickly and accurately following repetition, with repetition facilitating faster but fewer correct responses for non-words. Complex interactions between visual field of first and second presentation in the second experiment indicate asymmetric interhemispheric repetition priming effects. These results provide a broad picture of hemispheric asymmetries in word processing and of complex interaction between the hemispheres during word recognition.     

Connectivity among semantic associates: an fMRI study of semantic priming

Semantic priming refers to a reduction in the reaction time to identify or make a judgment about a stimulus that has been immediately preceded by a semantically related word or picture and is thought to result from a partial overlap in the semantic associates of the two words. A semantic priming lexical decision task using spoken words was presented in event-related fMRI and behavioral paradigms. Word pairs varied in terms of semantic relatedness and the connectivity between associates. Thirteen right-handed subjects underwent fMRI imaging and 10 additional subjects were tested in a behavioral version of the semantic priming task. It was hypothesized priming would be greatest, reaction time fastest, and cortical activation reduced the most for related word pairs of high connectivity, followed by related word pairs of low connectivity, and then by unrelated word pairs. Behavioral and fMRI results confirmed these predictions. fMRI activity located primarily in bilateral posterior superior and middle temporal regions showed modulation by connectivity and relatedness. The results suggest that these regions are involved in semantic processing.     

Repetition priming during the use and recall of numerical keypads

In two experiments, we investigated how repetition priming--a type of implicit memory--may be used to improve recall of the layout of digits on push-button telephones and calculators--an explicit memory task. In Experiment 1, participants were able to use repetition priming by pretending to dial a well-known telephone number in order to recall the telephone layout of digits, improving encoding of the number and preparation of the corresponding motor program. In contrast, no facilitative effect of known numbers on encoding and preparation was found for the calculator layout. Experiment 2 showed that the priming advantage of the telephone layout is not due to a general inadequacy of the calculator layout: Experimentally induced semantic repetition priming and motor repetition priming were observed for both the telephone layout and the calculator layout.     

Repetition blindness: The effects of stimulus modality and spatial displacement

Repetition blindness (Kanwisher, 1986, 1987) is the failure to detect repetitions of words in lists presented in rapid serial visual presentation (RSVP). Two questions were investigated in the present study. First, if repetition blindness is not found with auditory presentation, it would support a specifically visual account of the effect. Second, if displacement of the two instances in visual space eliminates repetition blindness, it would suggest that repetition blindness is restricted to instances in which identical stimuli are distinguished soley by temporal differences. In Experiment 1, the subjects omitted second occurrences of repeated words in verbatim recall of rapid sentences presented visually (in RSVP), but not auditorily (using compressed speech), indicating that repetition blindness is a modality-specific phenomenon. In Experiments 2 and 3, repetition blindness was observed even when two occurrences of a written word were presented in different locations, showing that distinct locations do not guarantee token individuation. The results are discussed within a model that distinguishes between processes of type recognition and token individuation.     

On imaging and seeing: Repetition priming and interactive views of imagery

Summary The interaction between perceptual and imaginal processes was investigated, with the use of the repetition-priming paradigm. The idea is that the overlap between processes employed in imagery and processes employed in perception will be reflected in the amount of transfer from one encounter with an item that engages perception or imagery and a second encounter that engages perception or imagery. The greater the overlap between perception and imagery, the greater the transfer between them should be. The results showed that perceptual and imaginal processes transferred maximally to themselves; that is, maximum transfer occurred when an item was processed in the same way on both encounters. Further, prior use of perceptual processes transferred to the use of imaginal processes, but not vice versa. These results are discussed as they relate to the interactive view of imagery, which holds that imagery relies on many of the same mental structures and processes as perception.Some of these data were presented at the Second Workshop on Imagery and Cognition, Padua, Italy, in September 1988.