Automatic Semantic Priming: The Contribution of Lexical- and Semantic-level Processes

It has recently been argued that the facilitation between associated primetarget pairs observed in automatic semantic priming tasks is due to lowlevel lexical effects. Any ''pure'' semantic priming is thought to be the result of strategic effects and does not therefore reflect automatic access to lexical semantic representations (e.g. Shelton & Martin, 1992). Not only are such claims based on a narrow definition of semantic relatedness as category comembership, but it is argued that the methodology employed by Shelton and Martin and other advocates of the intra-lexical priming hypothesis, who have attempted to dissociate semantic and associative effects by devising non-associated semantic prime-target pairs, is fundamentally flawed. Instead, an experiment is reported in which purely lexical-level primes are compared directly with semantic-level primes for the same target items in a sequential lexical decision task. Both types of prime produce facilitation, but only that from the semantic-level primes is significant. It is argued that, contrary to the intra-lexical priming hypothesis, semantic information is required for automatic semantic priming. If it were not, the lexical-level priming in this experiment would have been greater than the semantic-level priming. As it is, the reverse pattern is reported, providing support for the notion of a semantic contribution to the facilitation observed between associated prime-target pairs.     

Assessment of associative relations in alzheimer's disease: Evidence for preservation of semantic memory

Abstract

Semantic priming was assessed in Alzheimer's disease (AD), elderly control, and young control subjects with three lexical decision, continuous priming experiments. the stimuli were intracategory, associated pairs in Experiments 1 and 2 and varied types of associated pairs in Experiment 3. AD priming effects were equal to those of elderly control subjects; elderly and young control priming effects were also equal. We interpret this as evidence for the relative preservation of the semantic memory network in early AD, as in normal aging, at least to the extent necessary for normal access of concept nodes and normal automatic spreading activation between concept nodes. In a final study (Experiment 4) knowledge of the associations between the targets and related primes used in Experiments 1 and 2 was explicitly assessed; 20 out of 22 AD subjects showed perfect or close to perfect performance.     

The effects of associative and semantic priming in the lexical decision task

Four lexical decision experiments were conducted to examine under which conditions automatic semantic priming effects can be obtained. Experiments 1 and 2 analyzed associative/semantic effects at several very short stimulus-onset asynchronies (SOAs), whereas Experiments 3 and 4 used a single-presentation paradigm at two response-stimulus intervals (RSIs). Experiment 1 tested associatively related pairs from three semantic categories (synonyms, antonyms, and category coordinates). The results showed reliable associative priming effects at all SOAs. In addition, the correlation between associative strength and magnitude of priming was significant only at the shortest SOA (66 ms). When prime-target pairs were semantically but not associatively related (Experiment 2), reliable priming effects were obtained at SOAs of 83 ms and longer. Using the single-presentation paradigm with a short RSI (200 ms, Experiment 3), the priming effect was equal in size for associative + semantic and for semantic-only pairs (a 21-ms effect). When the RSI was set much longer (1,750 ms, Experiment 4), only the associative + semantic pairs showed a reliable priming effect (23 ms). The results are interpreted in the context of models of semantic memory.     

Predicting semantic priming at the item level

The current study explores a set of variables that have the potential to predict semantic priming effects for 300 prime-target associates at the item level. Young and older adults performed either lexical decision (LDT) or naming tasks. A multiple regression procedure was used to predict priming based upon prime characteristics, target characteristics, and prime-target semantic similarity. Results indicate that semantic priming (a) can be reliably predicted at an item level; (b) is equivalent in magnitude across standardized measures of priming in LDTs and naming tasks; (c) is greater following quickly recognized primes; (d) is greater in LDTs for targets that produce slow lexical decision latencies; (e) is greater for pairs high in forward associative strength across tasks and across stimulus onset asynchronies (SOAs); (f) is greater for pairs high in backward associative strength in both tasks, but only at a long SOA; and (g) does not vary as a function of estimates from latent semantic analysis (LSA). Based upon these results, it is suggested that researchers take extreme caution in comparing priming effects across different item sets. Moreover, the current findings lend support to spreading activation and feature overlap theories of priming, but do not support priming based upon contextual similarity as captured by LSA.     

Categorical priming of famous person recognition: a hitherto overlooked methodological factor can resolve a long-standing debate

The Burton, Bruce and Johnston [Burton, A. M., Bruce, V., & Johnston, R. A. (1990). Understanding face recognition with an interactive activation model. British Journal of Psychology, 81, 361-380] model of person recognition proposes that representations of known persons are connected by shared semantic attributes. This predicts that priming should be observed between persons from the same category, e.g. famous persons with the same occupation. Empirical investigations to date have produced mixed results, and comparison of methods suggests that priming based on shared occupation may have been suppressed by the presence of prime-target pairs representing a stronger relationship of close association. In the present experiment, 72 participants performed a familiarity decision to famous names preceded by close associates or members of the same occupational category. As predicted, categorical priming was observed in the group of participants for whom the same occupation prime-target pairs were presented before the close-associate pairs, but not in the group for whom the two types of relationship were intermixed. Associate priming was significant in both groups. These results are attributed to differing levels of processing of the primes, invoked by participants' observation of the most salient prime-target relationship.     

Semantic priming effects on picture and word processing

The effects of semantic priming on picture and word processing were assessed under conditions in which subjects were required simply to identify stimuli (label pictures or read words) as rapidly as possible. Stimuli were presented in pairs (a prime followed by a target), with half of the pairs containing members of the same semantic category and half containing unrelated concepts. Semantic relatedness was found to facilitate the identification of both pictures (Experiment 1) and words (Experiment 2), and obtained interactions of semantic relatedness and stimulus quality in both experiments suggested that semantic priming affects the initial encoding of both types of stimuli. In Experiment 3, subjects received pairs of pictures, pairs of words, and mixed pairs composed of a picture and a word or of a word and a picture. Significant priming effects were obtained on mixed as well as unmixed pairs, supporting the assumption that pictures and words access semantic information from a common semantic store. Of primary interest was the significantly greater priming obtained in picture-picture pairs than in word-word or mixed pairs. This suggests that, in addition to priming that is mediated by the semantic system, priming may occur in picture-picture pairs that results from the overlap in visual features common to the pictorial representations of objects from the same semantic category.     

A speed-accuracy analysis of word recognition in young and older adults

To measure age differences in the rate of semantic priming, studies vary the prime-target interval in lexical decision (LD) tasks. This provides no time limit on the target response. Thus, older adults' greater response times (RTs) could offer them more accumulated priming at the response compared with younger, faster adults. This study used a response deadline procedure in an LD task to equalize processing time across age groups. Although RTs did not significantly differ across age groups, older adults showed larger semantic priming effects than young adults. Semantic priming was also found with response accuracy (d'), but did not differ across age.     

Gender Stereotype Activation versus Lexical Semantic Activation: An ERP Study

It is an open question whether social stereotype activation can be distinguished from nonsocial semantic activation. To address this question, gender stereotype activation (GSA) and lexical semantic activation (LSA) were directly compared. EEGs were recorded in 20 participants as they identified the congruence between prime-target word pairs under four different conditions (stereotype congruent, stereotype incongruent, semantic congruent, and semantic incongruent). We found that congruent targets elicited faster and more accurate responses and reduced N400 amplitudes irrespective of priming category types. The N400 congruency effect (i.e., the difference between incongruity and congruity) started earlier and had greater amplitude for GSA than for LSA. Moreover, gender category priming induced a smaller N400 and a larger P600 than lexical category priming. These findings suggest that the brain is not only sensitive to both stereotype and semantic violation in the post-perceptual processing stage but can also differentiate these two information processes. Further, the findings suggest superior processing (i.e., faster and deeper processing) when the words are associated with social category and convey stereotype knowledge.     

Developmental differences in sensitivity to semantic relations among good and poor comprehenders: evidence from semantic priming

Semantic priming for category coordinates (e.g. CAT-DOG; AEROPLANE-TRAIN) and for pairs of words related through function (e.g. BROOM-FLOOR; SHAMPOO-HAIR) was assessed in children with good and poor reading comprehension, matched for decoding skill. Lexical association strength was also manipulated by comparing pairs of words that were highly associated with pairs that shared low association strength. Both groups of children showed priming for function-related words, but for the category co-ordinates, poor comprehenders only showed priming if the category pairs also shared high association strength. Good comprehenders showed priming for category-related targets, irrespective of the degree of prime-target association. These findings are related to models of language development in which category knowledge is gradually abstracted and refined from children's event-based knowledge and it is concluded that in the absence of explicit co-occurrence, poor comprehenders are less sensitive to abstract semantic relations than normal readers.     

Negative priming from masked words: retrospective prime clarification of center-surround inhibition?

Masked repetition and semantic priming effects were examined in 2 experiments. In Experiment 1, a masked-prime lexical decision task followed a phase of detection, semantic, or repetition judgments about masked words. In Experiment 2 participants made speeded pronunciations to target words after they tried to identify masked primes, and the proportion of semantically and identically related prime-target pairs was varied. Center-surround theory CT. H. Carr & D. Dagenbach, 1990; D. Dagenbach, T. H. Carr, & A. Wilhelmsen, 1989) predicts positive repetition priming but negative semantic priming when people attempt, but fail, to extract the meanings of masked words. A retrospective prime-clarification account, in contrast, predicts that semantic and repetition priming effects will vary (being positive or negative) as a function of expectations about the prime-target relation. The data support a retrospective prime-clarification account, which, unlike center-surround theory, correctly predicted negative repetition priming effects.     

Semantic activation in the absence of perceptual awareness

Participants performed a semantic categorization task on a target that was preceded by a prime word belonging either to the same category (20% of trials) or to a different category (80% of trials). The prime was presented for 33 msec and followed either immediately or after a delay by a pattern mask. With the immediate mask, reaction times (RTs) were shorter on related than on unrelated trials. This facilitatory priming reached significance at prime-target stimulus onset asynchronies (SOAs) of 400 msec or less and remained unaffected by task practice. With the delayed mask, RTs were longer on related than on unrelated trials. This reversed (strategic) semantic priming proved to be significant (1) only at a prime-target SOA of 400 msec or longer and (2) after the participants had some practice with the task. The present findings provide further evidence that perceiving a stimulus with and without phenomenological awareness can lead to qualitatively different behavioral consequences.     

Lexical but not semantic priming in Alzheimer's disease.

The hypothesis that patients with Alzheimer's disease (AD) have a disturbance in semantic processing was tested using a new lexical-priming task, threshold oral reading. Healthy elderly controls showed significant effects of priming for word pairs that are associatively related (words that reliably co-occur in word association tests) and for word pairs that are semantically related (high-frequency exemplars that belong to the same superordinate category but are not high-frequency associates). AD patients showed effects of priming for associatively related words but not for word pairs that are related only by shared semantic features. These results are consistent with the hypothesis that semantic processing is impaired in AD and suggest that independent networks of relationships among words and among concepts in semantic memory may be differentially disrupted with various forms of brain damage.     

An event-related brain potential analysis of visual word priming effects

Two experiments are reported that provide evidence on task-induced effects during visual lexical processing in a prime-target semantic priming paradigm. The research focuses on target expectancy effects by manipulating the proportion of semantically related and unrelated word pairs. In Experiment 1, a lexical decision task was used and reaction times (RTs) and event-related brain potentials (ERPs) were obtained. In Experiment 2, subjects silently read the stimuli, without any additional task demands, and ERPs were recorded. The RT and ERP results of Experiment 1 demonstrate that an expectancy mechanism contributed to the priming effect when a high proportion of related word pairs was presented. The ERP results of Experiment 2 show that in the absence of extraneous task requirements, an expectancy mechanism is not active. However, a standard ERP semantic priming effect was obtained in Experiment 2. The combined results show that priming effects due to relatedness proportion are induced by task demands and are not a standard aspect of online lexical processing.     

Semantic features and semantic categories: differences in rapid activation of the lexicon.

Robust priming was shown in a semantic categorization task for prime-target pairs which shared semantic features (e.g., pumpkin-squash). Priming facilitation for these pairs was demonstrated at extremely rapid prime exposures (28 and 43 ms) and increased with prime duration. The onset and amount of facilitation differed significantly for these semantic, nonassociative pairs and for associative-semantic prime-target pairs (e.g., cow-bull). The latter pairs produced facilitation, but later (at prime-target SOAs of 70 and 200 ms) and of lesser magnitude. These results are discussed in relation to three current models of semantic memory: spreading activation, compound cue, and distributed models.     

Semantic priming in young and older adults: evidence for age constancy in automatic and attentional processes

Automatic and attentional components of semantic priming and the relation of each to episodic memory were evaluated in young and older adults. Category names served as prime words, and the relatedness of the prime to a subsequent lexical decision target was varied orthogonally with whether the target category was expected or unexpected. At a prime-target stimulus-onset asynchrony (SOA) of 410 ms, target words in the same category had faster lexical decision latencies than did different category targets. This effect was not significant at a 1,550-ms SOA and was attributed to automatic processes. Expected category targets had faster latencies than unexpected category targets at the 410-ms SOA, and the magnitude of the effect increased at the 1,550-ms SOA. This effect was attributed to attentional processes. These patterns of priming were obtained for both age groups, but in a surprise memory test older adults had poorer recall of primes and targets. We discuss the implications of these results for the hypothesis that older adults suffer deficits in selective attention and for the related hypothesis that attentional deficits impair semantic processing, which causes memory decrements in old age.     

Influence of prime-target relationship on semantic priming effects from words in a lexical-decision task

The present research examines the influence of prime-target relationship (associative and categorical versus categorical only) on priming effects from attended and ignored parafoveal words. Participants performed a lexical-decision task on a single central target, which was preceded by two parafoveal prime words, one of which (the attended prime) was spatially precued. The results showed reliable positive and negative priming effects from attended and ignored words, respectively. However, this priming pattern was observed only for the "associative and categorical", but not for the "categorical only" relationship condition. These results suggest that the lack of semantic priming effects from words in some prior studies may be attributed to the kind of material used (i.e. weakly-associated word pairs).     

Priming effects in prospective memory

Abstract

The objective of this study was to examine whether an increased activation of knowledge structures facilitates memory for future actions. Priming effects were manipulated by giving subjects a category fluency task for half of the target categories used in the subsequent prospective memory task. In this task, younger and older adults performed an action whenever an instance of a given semantic category occurred in the context of a free association task. The degree of retrieval support was varied by using typical and atypical category instances as targets. Although reliable priming effects were observed for both age groups, the magnitude of priming interacted with the degree of retrieval support. Older adults showed priming effects for typical targets only, whereas the opposite pattern of results was obtained for younger adults. These findings indicate that, in addition to retrieval-related factors, the operations performed at the time of planning also contribute to optimal prospective remembering.     

Age-related differences in lexical access, spreading activation, and simple pronunciation

An experiment was conducted to address age-related differences in lexical access, spreading activation, and pronunciation. Both young and older adults participated in a delayed pronunciation task to trace the time course of lexical access and a semantic priming task to trace the time course of spreading activation. In the delayed pronunciation task, subjects were presented a word and then, after varying delays, were presented a cue to pronounce the word aloud. Older adults benefited considerably more from the preexposure to the word than did the younger adults, suggesting an age-related difference in lexical access time. In the semantic priming pronunciation task, semantic relatedness (related vs. neutral), strength of the relationship (high vs. low), and prime-target stimulus onset asynchrony (200 ms, 350 ms, 500 ms, 650 ms, and 800 ms) were factorially crossed with age to investigate age-related differences in the buildup of semantic activation across time. The results from this task indicated that the activation pattern of the older adults closely mimicked that of the younger adults. Finally, the results of both tasks indicated that older adults were slower at both their onset to pronounce and their actual production durations (i.e., from onset to offset) in the pronunciation task. The results were interpreted as suggesting that input and output processes are slowed with age, but that the basic retrieval mechanism of spreading activation is spared by age.     

Opposite ERP effects for conscious and unconscious semantic processing under continuous flash suppression

We examined whether semantic processing occurs without awareness using continuous flash suppression (CFS). In two priming tasks, participants were required to judge whether a target was a word or a non-word, and to report whether the masked prime was visible. Experiment 1 manipulated the lexical congruency between the prime-target pairs and Experiment 2 manipulated their semantic relatedness. Despite the absence of behavioral priming effects (Experiment 1), the ERP results revealed that an N4 component was sensitive to the prime-target lexical congruency (Experiment 1) and semantic relatedness (Experiment 2) when the prime was rendered invisible under CFS. However, these results were reversed with respect to those that emerged when the stimuli were perceived consciously. Our findings suggest that some form of lexical and semantic processing can occur during CFS-induced unawareness, but are associated with different electrophysiological outcomes.     

Unconscious semantic activation depends on feature-specific attention allocation

We examined whether semantic activation by subliminally presented stimuli is dependent upon the extent to which participants assign attention to specific semantic stimulus features and stimulus dimensions. Participants pronounced visible target words that were preceded by briefly presented, masked prime words. Both affective and non-affective semantic congruence of the prime-target pairs were manipulated under conditions that either promoted selective attention for affective stimulus information or selective attention for non-affective semantic stimulus information. In line with our predictions, results showed that affective congruence had a clear impact on word pronunciation latencies only if participants were encouraged to assign attention to the affective stimulus dimension. In contrast, non-affective semantic relatedness of the prime-target pairs produced no priming at all. Our findings are consistent with the hypothesis that unconscious activation of (affective) semantic information is modulated by feature-specific attention allocation.