Are morphological effects distinguishable from the effects of shared meaning and shared form?

Effects of orthographically and semantically related primes were compared with morphologically related primes in an immediate (Experiment 1) and a long-term (Experiment 2) lexical decision task. Morphological relatedness produced facilitation across a range of prime durations (32-300 ms) as well as when items intervened between prime and target, and its magnitude increased with prime duration. Semantic facilitation and orthographic inhibition arose only in the immediate priming task. Moreover, morphological effects were significantly greater than the sum of semantic and orthographic effects at a stimulus onset asynchrony of 300 ms but were not reliably different at shorter durations. The adequacy of an account that describes morphological relatedness as distinct from the composite effects of semantic and orthographic similarity must account for changes in additivity across prime durations.     

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.     

Semantic priming and word repetition: The two effects are both additive and interactive

The additivity of semantic priming and word repetition was tested in an auditory perceptual identification task, with a view to tease apart automatic and strategic priming mechanisms. The factors Word Repetition, Semantic Priming, and Practice interacted. Word Repetition and Semantic Priming were additive in the first half of the experiment, but not in the second half. A more detailed analysis indicated that Word Repetition was additive with automatic semantic priming but not with strategic semantic priming. Results suggested that the word-repetition effect depends in part on conscious strategic anticipation processes.Parts of this study were presented at the 25th International Congress of Psychology, Brussels, 1992, and at the 34th Tagung experimentell arbeitender Psychologen, Osnabrück, 1992     

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.     

Unconscious task set priming with phonological and semantic tasks

Whether unconscious stimuli can modulate the preparation of a cognitive task is still controversial. Using a backward masking paradigm, we investigated whether the modulation could be observed even if the prime was made unconscious in 100% of the trials. In two behavioral experiments, subjects were instructed to initiate a phonological or semantic task on an upcoming word, following an explicit instruction and an unconscious prime. When the SOA between prime and instruction was sufficiently long (84 ms), primes congruent with the task set instruction led to speedier responses than incongruent primes. In the other condition (36 ms), no task set priming was observed. Repetition priming had the opposite tendency, suggesting the observed task set facilitation cannot be ascribed solely to perceptual repetition priming. Our results therefore confirm that unconscious information can modulate cognitive control for currently active task sets, providing sufficient time is available before the conscious decision.     

Nice wor_ if you can get the wor_: subliminal semantic and form priming in fragment completion

Two experiments investigated subliminal semantic and form priming in a word-completion task. Visual gap-words with a dominant and a subordinate solution were preceded by form-related or by semantically related words, which were briefly presented and sandwich-masked. Priming of the subordinate solution was assessed in Experiment 1, relative to a neutral condition. Both solutions were primed in Experiment 2. In the absence of conscious prime recognition, both semantic and form primes reliably increased the probability with which the primed solution was given. With our variant of fragment-completion, response priming can be ruled out as explanation. Moreover, effects were already present at first presentation, excluding an interpretation in terms of partial awareness due to massive repetition. The data demonstrate automatic activation at both form and semantic levels in the absence of conscious awareness.     

Controlling the unconscious: attentional task sets modulate subliminal semantic and visuomotor processes differentially

Are unconscious processes susceptible to attentional influences? In two subliminal priming experiments, we investigated whether task sets differentially modulate the sensitivity of unconscious processing pathways. We developed a novel procedure for masked semantic priming of words (Experiment 1) and masked visuomotor priming of geometrical shapes (Experiment 2). Before presentation of the masked prime, participants performed an induction task in which they attended to either semantic or perceptual object features designed to activate a semantic or perceptual task set, respectively. Behavioral and electrophysiological effects showed that the induction tasks differentially modulated subliminal priming: Semantic priming, which involves access to conceptual meaning, was found after the semantic induction task but not after the perceptual induction task. Visuomotor priming was observed after the perceptual induction task but not after the semantic induction task. These results demonstrate that unconscious cognition is influenced by attentional control. Unconscious processes in perceptual and semantic processing streams are coordinated congruently with higher-level action goals.     

Semantic priming in the pronunciation task: The role of prospective prime-generated expectancies

In the relatedness proportion effect, semantic priming increases with an increase in the probability that a word prime will be followed by a semantically related word target. This effect has frequently been obtained in the lexical decision task but not in a pronunciation task. In the present experiment, relatedness proportion was manipulated in two pronunciation tasks, one with and one without nonword targets, using category names as primes. In both tasks, a relatedness proportion effect occurred for high-dominance category exemplars but not for low-dominance category exemplars. These results converge with recent lexical decision results in suggesting that semantic priming in pronunciation is affected by a prospective prime-generated expectancy that is modulated by the relatedness proportion.     

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.     

Psychophysiological evidence of response conflict and strategic control of responses in affective priming

This experiment investigated the role of conflict in the response and evaluative categorization systems in the affective congruency effect using event-related brain potentials (ERPs). Participants completed a primed evaluative decision task in which the proportion of congruent to incongruent trials was manipulated. The size of the affective congruency effect increased along with the proportion of congruent trials. ERP data identified the locus of this effect in the response system: the lateralized readiness potential (LRP) showed that preferential response activation occurred in motor cortex following prime onset, and the fronto-central N2 (conflict monitoring) component indicated that conflict occurred when the response activated by the prime differed from the target response, irrespective of the affective congruency of the prime and target. The extent of this conflict covaried with strategic processing of primes, as participants directed less attention to primes that were likely to elicit conflict. These data support a response conflict account of affective congruency effects in the evaluative decision task and indicate that strategic control of attention is important in determining the extent to which conflict occurs.     

Masked semantic priming effects from the prime's orthographic neighbours

The present research involved masked priming lexical decision experiments using, in the crucial condition, masked primes with an orthographic neighbour that was semantically related to the target. Regardless of the lexicality of the prime, a significant priming effect was observed when the relatedness proportion (RP, that is, the proportion of primes and targets that were directly related on the “word” trials) was 2/3 (Experiments 1 and 2). No effect emerged, however, when the RP was 0 (Experiment 3). These results indicate that lexical/semantic activation arises automatically for both the prime and its neighbours. This activated lexical/semantic information appears to be evaluated together with the lexical/semantic information activated by the target, creating a decision bias during the decision-making process, but only when that information often provides a clue as to the nature of the correct decision. Our results, therefore, also provide support for the retrospective account of masked semantic priming.     

Unconscious priming of task sets: The role of spatial attention

Unconscious stimuli activate task sets, mental programs that orchestrate performance of complex tasks, but the role of attention in such effects has not been addressed. In previous studies, unconscious prime stimuli appeared at attended locations and were explicitly specified in the task instructions; spatial attention to the prime and/or a specific conscious attentional set may thus be required for such unconscious activation to arise. In the present experiments, a learning phase established associations between unconscious prime stimuli and performance of two tasks. These associations influenced task performance in a subsequent test phase, even though the primes were not specified in current task instructions. This is the first demonstration that unconscious stimuli can prime task sets independently of a current attentional set that specifies stimulus-task mappings. Such priming was not influenced by spatial attention cues, in contrast to clear attention influences in comparison trials that mimicked conditions employed by previous studies.     

Beyond binary judgments: Prime validity modulates masked repetition priming in the naming task

Bodner and Masson (2001) reported that masked repetition priming of lexical decisions is often greater when the repetition primes appear on a high, rather than a low, proportion of trials. They suggested that processing episodes are constructed for masked primes and that recruitment of those episodes is affected by the probability that the prime will be useful for processing the target. If context-sensitive recruitment of primes is a general mechanism, a similar effect should also occur in a nonbinary response task. In accord with this hypothesis, using the naming task and a 45-msec prime duration, we show that masked repetition priming effects for uppercase words, case-alternated words, and pseudohomophones were greater when .8 rather than .2 of the trials involved repetition (vs. unrelated) primes. Prime validity effects are consistent with a memory recruitment view of priming but may be difficult to explain using activation-based mechanisms.     

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.     

False memories and lexical decision: even twelve primes do not cause long-term semantic priming

Semantic priming effects are usually obtained only if the prime is presented shortly before the target stimulus. Recent evidence obtained with the so-called false memory paradigm suggests, however, that in both explicit and implicit memory tasks semantic relations between words can result in long-lasting effects when multiple 'primes' are presented. The aim of the present study was to investigate whether these effects would generalize to lexical decision. In four experiments we showed that even as many as 12 primes do not cause long-term semantic priming. In all experiments, however, a repetition priming effect was obtained. The present results are consistent with a number of other results showing that semantic information plays a minimal role in long-term priming in visual word recognition.     

Repetition proportion affects masked priming in nonspeeded tasks

Masked repetition priming is often greater when a larger proportion of trials involve repetition primes, suggesting that a context-sensitive unconscious process may be operating. Two recent studies have failed to obtain an effect of prime proportion in the perceptual identification (PI) task, suggesting that the effect may not occur in nonspeeded tasks. Contrary to this possibility, we report proportion effects with masked repetition primes in two nonspeeded tasks: PI and fragment completion (FC). A proportion effect occurred in the accuracy measure only in the FC task, but it occurred in the reaction time measure in both tasks. Prior failures to find proportion effects in the PI task thus may have been due, in part, to the dependent measure used. We interpret our findings in light of several recent accounts of prime proportion effects with brief primes.     

Interactions of reading and semantics along the ventral visual processing stream

Converging evidence supports a distributed-plus-hub view of semantic processing, in which there are distributed modular semantic sub-systems (e.g., for shape, colour, and action) connected to an amodal semantic hub. Furthermore, object semantic processing of colour and shape, and lexical reading and identification, are processed mainly along the ventral stream, while action semantic processing occurs mainly along the dorsal stream. In Experiment 1, participants read a prime word that required imagining either the object or action referent, and then named a lexical word target. In Experiments 2 and 3, participants performed a lexical decision task (LDT) with the same targets as in Experiment 1, in the presence of foils that were legal nonwords (NW; Experiment 2) or pseudohomophones (PH; Experiment 3). Semantic priming was similar in effect size regardless of prime type for naming, but was greater for object primes than action primes for the LDT with PH foils, suggesting a shared-stream advantage when the task demands focus on orthographic lexical processing. These experiments extend the distributed-plus-hub model, and provide a novel paradigm for further research.     

The dependence of semantic relatedness effects upon prime processing

The semantic relationship between a prime and a target word has been shown to affect the speed at which the target word is processed. This series of experiments investigated how the semantic priming effect is influenced by the nature of the task performed on the prime word. Subjects were asked to perform either a naming or a letter-search task on the prime word and either a lexical-decision or color-naming task on the target word. When the primes were named, response times for the target words were facilitated in the lexical-decision task and inhibited in the color-naming task. However, these effects were eliminated or reduced to an insignificant level when the primes were searched for letters. We suggest that in order to produce the usual priming effect, the primes have to be processed for meaning rather than probed for constituents.     

Cross-notation number priming investigated at different stimulus onset asynchronies in parity and naming tasks

In this paper, a parity judgment task and a number naming task were used to investigate cross-notational number priming. Primes and targets could be verbal (e.g., seven) or Arabic numbers (e.g., 7), and were always presented in a different notation within the same trial (either a verbal prime and an Arabic target or an Arabic prime and a verbal target). Previous experiments showed that response latencies increase when the distance between prime and target increases (for example, in a naming task, seven is pronounced faster after 6 than after 5). This semantic distance priming effect was the same for Arabic and verbal targets and was the same for within-notation trials as for cross-notation trials. In the present experiments, we wanted to investigate whether the cross-notational priming effect also occurs at SOAs shorter than the ones used in previous experiments. Therefore, we used SOAs of 43, 57, 86, and 115 ms. Semantic distance effects were indeed present at these shorter SOAs: Processing times in the semantic parity judgment task and in the non-semantic naming task increased when the distance between prime and target increased. The results are discussed and integrated within an interactive dual-route model of number processing that postulates that the impact of the semantic and the non-semantic route depends on the task and the notation of the stimuli.     

Repeated masked category primes interfere with related exemplars: new evidence for negative semantic priming

In 4 experiments, the authors found evidence for negatively signed masked semantic priming effects (with category names as primes and exemplars as targets) using a new technique of presenting the masked primes. By rapidly interchanging prime and mask during the stimulus onset asynchrony, they increased the total prime exposure to a level comparable with that of a typical visible prime condition without increasing the number of participants having an awareness of the prime. The negative effect was observed for only low-dominance exemplars and not for high-dominance exemplars. The authors found it using lexical decision (Experiments 1 and 2), lexical decision with a response-window procedure (Experiment 3), and the pronunciation task (Experiment 4). The results are discussed with regard to different theories on semantic priming.