Semantic priming in the prime task effect: Evidence of automatic semantic processing of distractors

The automaticity of the semantic processing of words has been questioned because of the reduction of semantic priming when the prime word is processed nonsemantically--for example, in letter search (the prime task effect). In two experiments, prime distractor words produced semantic priming in a subsequent lexical decision task, but with the direction of priming (positive or negative) depending on the prime task. Lexico-semantic tasks produced negative semantic priming, whereas letter search produced positive semantic priming. These results are discussed in terms of task-based inhibition. We argue that, given the results from the distractors, the absence of semantic priming does not indicate an absence of semantic activation but reflects the action of control processes on prepotent responses when less practiced responses are needed.     

Word-based grouping affects the prime-task effect on semantic priming

Semantic priming between words is reduced or eliminated if a low-level task such as letter search is performed on the prime word (the prime task effect), a finding used to question the automaticity of semantic processing of words. This idea is critically examined in 3 experiments with a new design that allows the search target to occur both inside and outside the prime word. The new design produces the prime task effect (Experiment 1) but shows semantic negative priming when the target letter occurs outside the prime word (Experiments 2 and 3). It is proposed that semantic activation and priming are dissociable and that inhibition and word-based grouping are responsible for reduction of semantic priming in the prime task effect.     

On the interaction between linguistic and pictorial systems in the absence of semantic mediation: Evidence from a priming paradigm

Use of the letter search task in the context of the priming paradigm has proved to be an invaluable tool for the investigation of the strategic control of processes involved in word recognition. In particular, previous findings that letter search on a prime word interferes with the priming of semantically/associatively related targets, but not with the priming of either identical or morphologically related targets, suggests that letter search may selectively interfere with semantic processing, leaving other levels of processing intact. In the present experiments, this investigation was extended by exploring the priming of pictures following letter search of either a same-concept word (repetition priming) or a semantically/associatively related word (semantic priming). There was significant repetition priming of picture categorization following both silent reading and letter search of the prime word (Experiments 1 and 2). In contrast, semantic priming of pictures was found only following silent reading of the prime; there was no semantic priming following letter search of the prime (Experiment 2). This pattern of results suggests that focusing attention at the letter level during prime processing selectively attenuates activation of the semantic system by the prime. It does not prevent the spread of activation between the lexical and pictogen levels of representation of a given concept.     

Semantic priming in visual word recognition: Activation blocking and domains of processing

The fact that letter search on a prime eliminates the typically robust semantic priming effect in lexical decision is often attributed to the “shallowness” of the prime-processing task. In three experiments we investigated this claim by using two different “shallow” prime-processing tasks: letter search and color identification. Consistent with previous reports, lexical decisions to semantically related targets were not facilitated when subjects searched the prime for a probe letter. In contrast, semantic priming was observed following a color discrimination task on the prime. We suggest that a levels-of-processing interpretation is not an adequate framework for understanding these data. Instead, a domain-specific processing account is offered in which explicit processing at the letter level (as in letter search) makes demands on resources (e.g., activation) that drives processing at the semantic level. This competition is resolved by establishing a temporary activation block at the lexical-semantic interface, which results in the elimination or attenuation of semantic priming. In contrast, global judgment of color is viewed as a domain that does not make demands on the resources that drive the visual word recognition machinery. There is therefore no need for an activation block, and semantic priming is not prevented.     

Semantic activation and letter search: Blocking or suppression?

Two experiments investigated associative priming with a letter-search prime task where either the prime and letter probe were presented simultaneously, or the letter probe appeared 200 ms (Experiment 1) or 300 ms (Experiment 2) after the prime. Weak associative priming was observed in both experiments, but unlike Stolz and Besner (1996) we found no evidence that priming was increased when the probe was delayed. However, strong associative priming was observed when a semantic decision had to be made on the prime (Experiment 3). Our results are consistent with an account where semantic activation of the prime occurs but its action on the target is suppressed by the prime task. The persistence of weak priming effects with the letter search task is explained in terms of the low-frequency items used.     

Levels and speed of processing effects on word analysis

Previous work on semantic priming effects has suggested that priming is contingent upon semantic analysis of the prime stimulus. In the present series of experiments, subjects in Grade 3, Grade 6, and college performed variants of a priming task in which semantic (lexical decision) as well as fast (case judgment) and slow (letter search) nonsemantic levels of processing were required for both prime and target stimuli. Contrary to a levels of processing hypothesis, context effects were not simple functions of the level at which the prime was processed. Priming effects were found with a slow nonsemantic prime task (letter search), but generally not with a fast nonsemantic analysis of the prime (case judgment). The form of the priming effect when the prime was processed semantically by a lexical decision depended on the relationship between prime and target processing: a switch from semantic prime processing to nonsemantic target processing produced Stroop-like interference, with other combinations of prime and target processing producing facilitation. By using a series of discrimination, focusing, and classification tasks in a Garner (1978) paradigm, it was possible to determine how subjects were processing the semantic and nonsemantic dimensions, and these perceptual strategies were compared across educational levels to account for the priming effects. Our results suggest that context effects need to be understood in terms of the speeds of processing of different codes of information inherent in words.     

When are morphemic and semantic priming observed in visual word recognition?

J. Stolz and D. Besner (1998) reported a dissociation between morphemic and semantic priming in the context of lexical decision. Morphemic priming was observed following letter search on the prime display, but semantic priming was not. Participants in the present experiment identified the colour of a single letter in the prime display before making a lexical decision to the target. Both morphemic and semantic priming were observed. These results are discussed in relation to the observation that identifying the colour of a single letter of a word in the Stroop task is associated with a reduction in the size of the Stroop effect as compared to when all letters are coloured.     

Congruency effects in the letter search task: Semantic activation in the absence of priming

Semantic priming is typically eliminated when participants perform a letter search on the prime, suggesting that semantic activation is conditional upon one's attentional goals. However, in such studies, semantic activation (or the lack thereof) is not measured during the letter search task itself but, instead, is inferred on the basis of the responses given to a later target. In the present study, direct online evidence for semanticactivation was tested using words whose meaning should bias either a positive or a negative response (e.g.,present vs. absent). In Experiment 1, a semantic congruency effect was obtained, with faster responses when the word meaning matched the required response. Experiment 2 replicated the congruency effect while, simultaneously, showing the elimination of semantic priming. It is concluded that letter search does not affect the initiation of semantic activation. Possible accounts for the elimination of priming following letter search include activation-based suppression and transfer-inappropriate processing.     

Attention constraints of semantic activation during visual word recognition

The reduction of semantic priming following letter search of the prime suggests that semantic activation can be blocked if attention is allocated to the letter level during word processing. Is this true even for the very fast-acting component of semantic activation? To test this, the authors explored semantic priming of lexical decision at stimulus onset asynchronies (SOAs) of either 200 or 1,000 ms. Following semantic prime processing, priming occurred at both SOAs. In contrast, no priming occurred at the long SOA following letter-level processing. Of greatest interest, at the short SOA there was priming following the less demanding consonant/vowel task but not following the more attention-demanding letter search task. Hence, semantic activation can occur even when attention is directed to the letter level, provided there are sufficient resources to support this activation. The authors conclude that the default setting during word recognition is for fast-acting activation of the semantic system.     

Capacity demands of automatic processes in semantic priming

Ben-Gurion University of the Negev, Beer Sheva, Israel In three experiments, we examined the effects of prime-target stimulus onset asynchrony (SOA) and the proportion of related primes and targets (relatedness proportion, or RP) on semantic priming when the prime was either named or was searched for a specific letter. In Experiment 1, with an RP of. 50, priming occurred at SOAs of 240 and 840 msec when the prime was named, but no priming was found at either SOA when the prime was searched for a letter. In Experiment 2 the RP was either. 20 or. 80, and the SOA was set at 1, 700 msec; priming again was found in both conditions when the prime was named, but only in the RP.80 condition when a letter search task was performed on the prime. In Experiment 3, both the proportion of related trials and SOA were varied; as in the previous experiments, no priming effects were found with the letter search task for either SOA in the RP.20 condition, but the priming effect was reinstated in the RP.80 condition. These results are discussed with respect to how limited capacity resources are allocated and how they influence semantic priming effects.     

Modulating semantic feedback in visual word recognition

According to the interactive activation framework proposed by McClelland and Rumelhart (1981), activation spreads both forward and backward between some levels of representation during visual word recognition. An important boundary condition, however, is that the spread of activation from lower to higher levels can be prevented (e.g., explicit letter processing during prime processing eliminates the well-documented semantic priming effect). Can the spread of activation from higher to lower levels also be prevented? This question was addressed with a choice task procedure in which subjects read a prime word and then responded to a target, performing either lexical decision or letter search depending on the color of the target. A semantic context effect was observed in lexical decision, providing evidence of semantic-level activation. In contrast, there was no semantic context effect in the letter search task, despite evidence of lexical involvement: Words were searched faster than nonwords. Further evidence of lexical involvement in the letter search task appeared in Experiment 2 in the form of greater identity priming for words than for nonwords. The results of these experiments are consistent with the conclusion that feedback from the semantic level to the lexical level can be blocked. Hence, between-level activation blocks can be instantiated in both bottom-up and top-down directions.     

Automatic processes in lexical access and spreading activation.

The semantic priming effect can be reduced or eliminated depending on how the prime word is processed. The experiments reported here investigate this prime task effect. Two experiments used identity and semantic priming tasks to determine whether the prime word is encoded at a lexical level under letter-search conditions. When the prime task was naming, both identity and semantic priming occurred; however, when a letter-search task was performed on the prime word, only identity priming occurred, thus supporting the argument that the search task affects activation of semantic associates rather than lexical access of the prime word. Another experiment demonstrated that this identity priming was the result of lexical processes rather than of letter-by-letter priming. A cross-modal priming technique demonstrated that the letter-search prime task does not actively suppress activation of semantic associates. The implications of these results for automaticity and for proposed mechanisms of priming are discussed.     

Automatic semantic activation is no myth: semantic context effects on the N400 in the letter-search task in the absence of response time effects

The claim that semantic activation is an automatic process was recently called a myth, on the basis of the finding that if letter search is performed on a prime word, semantic priming effects on response time are eliminated, whereas repetition effects are preserved. The absence of semantic activation, however, cannot be validly inferred from the lack of response time effects, and converging evidence is needed. To this end, we examined the event-related potential correlate of priming, the N400 amplitude modulation, in a letter-search priming paradigm. Our experiment replicated the response time effects and demonstrated that the N400 amplitude successfully differentiates cross-case repetition priming, semantic priming, and neutral conditions. The results clearly indicate that the meaning of the prime word was processed and that semantic activation indeed was present in the letter-search task. The notion that semantic activation is an automatic process should not be abandoned prematurely.     

Associative and phonological priming effects after letter search on the prime

Responses to target words typically are faster and more accurate after associatively related primes (e.g., "orange-juice") than after unrelated primes (e.g., "glue-juice"). This priming effect has been used as an index of semantic activation, and its elimination often is cited as evidence against semantic access. When participants are asked to perform a letter search on the prime, associative priming typically is eliminated, but repetition and morphological priming remain. It is possible that priming survives letter search when it arises from activity in codes that are represented before semantics. This experiment examined associative and phonological priming to determine whether priming from phonologically related rhymes would remain after letter search (e.g., "moose-juice"; rhyming items were orthographically dissimilar). When participants read the primes, equivalent associative and phonological priming effects were obtained; both effects were eliminated after letter search. The impact of letter search on semantic and phonological access and implications for the structural arrangement of lexical and semantic memory are discussed.     

Does<Emphasis Type="SmallCaps">LGHT</Emphasis> prime<Emphasis Type="SmallCaps">DARK</Emphasis>? Masked associative priming with addition neighbors

We present two masked priming lexical decision experiments in which we examined whether a nonword prime word would activate associative/semantic information from its corresponding addition neighbor (e.g.,lght-DARK via the addition neighborlight), producing associative/semantic priming. The rationale was the following: If a nonword prime with a missing letter produced a semantic/associative priming effect, this would clearly indicate that this nonword was activating the lexical/semantic representations of its base word, thereby reinforcing the models of visual-word recognition in which the orthographic representations produced bylght (orligt) andlight are quite similar (e.g., SOLAR, SERIOL, open-bigram, and overlap models). The results showed that the magnitude of the masked associative priming effect with subset primes was remarkably similar to that of the priming effect with the corresponding word prime. Furthermore, the magnitude of the associative priming effect was similar when the deleted letter was a vowel and when the deleted letter was a consonant.     

Semantic processing in visual word recognition: activation blocking and domain specificity

Lexical decision to a target is typically facilitated when a related prime is simply read, but is typically eliminated if subjects carry out a letter search on the prime when probe and prime appear simultaneously. Three experiments involving the addition of a task-irrelevant word to this prime search paradigm address (1) Stolz and Besner’s (1996, 1998) account in which semantic priming is eliminated because letter search on the prime instantiates an activation block between lexical and semantic levels of representation, (2) Chiappe, Smith, and Besner’s (1996) account that activation blocking is domain specific, and (3) Neely and Kahan’s (2001) claim that semantic activation is context independent and capacity free. The results are (1) consistent with the account that activation blocking is general to a level, rather than item specific, (2) consistent with the account that activation blocking is domain specific, and (3) inconsistentwith the claim that semantic activation is context independent and capacity free.     

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.     

The use of abstract graphemic information in lexical access

Three experiments investigated the nature of the information required for the lexical access of visual words. A four-field masking procedure was used, in which the presentation of consecutive prime and target letter strings was preceded and followed by presentations of a pattern mask. This procedure prevented subjects from identifying, and thus intentionally using, prime information. Experiment I extablished the existence of a semantic priming effect on target identification, demonstrating the lexical access of primes under these conditions. It also showed a word repetition effect independent of letter case. Experiment II tested whether this repetition effect was due to the activation of graphemic or phonemic information. The graphemic and phonemic similarity of primes and targets was varied. No evidence for phonemic priming was found, although a graphemic priming effect, independent of the physical similarity of the stimuli, was obtained. Finally Experiment III demonstrated that, irrespective of whether the prime was a word or a nonword, graphemic priming was equally effective. In both Experiments II and III, however, the word repetition effect was stronger than the graphemic priming effect. It is argued that facilitation from graphemic priming was due to the prime activating a target representation coded for abstract (non-visual) graphemic features, such as letter identities. The extra facilitation from same identity priming was attributed to semantic as well as graphemic activation. The implications of these results for models of word recognition are discussed.     

不同控制水平下的汉字语义加工

字词语义的加工是否受其它加工过程或操纵手段的控制一直是自动化研究的热点,以往针对英文字词的研究结果不尽一致。本研究以在该类研究中比英文单词更具优越性的汉字为材料,采用部件搜索任务,通过操纵控制水平的强弱探讨汉字的语义加工是否受控制这一问题。实验一考察汉字的语义是否受浅水平加工和无意识操纵的控制（低控制水平）;实验二探讨增强了的控制水平是否能够控制语义的加工。结果在实验一中发现了语义负启动效应;实验二出现了正启动和负启动效应。该结果表明,控制机制并不能阻止汉字语义加工本身的发生,仅能对已经产生激活的语义进行调控,提示汉字的语义加工是不可控的。     

Faster might not be better: Pictures may not elicit a stronger unconscious priming effect than words when modulated by semantic similarity

It has been suggested that unconscious semantic processing is stimulus-dependent, and that pictures might have privileged access to semantic content. Those findings led to the hypothesis that unconscious semantic priming effect for pictorial stimuli would be stronger as compared to verbal stimuli. This effect was tested on pictures and words by manipulating the semantic similarity between the prime and target stimuli. Participants performed a masked priming categorization task for either words or pictures with three semantic similarity conditions: strongly similar, weakly similar, and non-similar. Significant differences in reaction times were only found between strongly similar and non-similar and between weakly similar and non-similar, for both pictures and words, with faster overall responses for pictures as compared to words. Nevertheless, pictures showed no superior priming effect over words. This could suggest the hypothesis that even though semantic processing is faster for pictures, this does not imply a stronger unconscious priming effect.