Semantic and perceptual priming: How similar are the underlying mechanisms?

Both semantic priming and perceptual priming consist of facilitation of the identification of primed stimuli and inhibition of the identification of nonprimed stimuli. The similarities between the two phenomena suggest that a common attentional mechanism underlies both, and this has been explicitly proposed by several attention theorists. In this article it is argued that the phenomena of semantic and perceptual priming are qualitatively different, perceptual priming reflecting a sensitivity change in the recognition process brought about by attention, and semantic priming reflecting a bias change in the recognition process brought about by attention. Because different mechanisms are required to produce sensitivity and bias changes, this implies that the attentional mechanisms responsible for semantic and perceptual priming are distinct. In terms of recent discussions of the modularity versus the unity of cognitive architecture, the present conclusion supports a modular architecture for attentional processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Semantic priming and sensitivity in lexical decision.

M. J. Farah (1989) argued that qualitatively different attentional mechanisms underlie perceptual and semantic priming. The crux of this argument is her claim that semantic priming, unlike perceptual priming, does not alter sensitivity. It is suggested that the evidential base for this claim is weak, and 4 experiments are reported in which semantic priming altered sensitivity. In Exps 1, 3, and 4, lexical decision was reliably primed by associates, and signal detection analyses indicated that both sensitivity and bias were affected. In Exp 2, significant semantic priming was also demonstrated with a 2-alternative forced choice paradigm in which performance is independent of criterion bias. These results challenge the claim that semantic priming does not alter sensitivity. The broader implications of these results are considered for attentional mechanisms and for J. A. Fodor's (1983, 1985) modularity claims. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Signal Detection Theory Analyses of Semantic Priming in Word Recognition.

Word recognition, semantic priming, and cognitive impenetrability research have used signal detection theory (SDT) measures to separate perceptual and postperceptual processes. In the D. Norris (1986) checking model and model simulation (D. Norris, 1995), priming alters only postperceptual word decision criteria: Stimulus-related priming reduces uncertainty, increasing sensitivity; stimulus-unrelated priming increases false alarms more than hits, reducing sensitivity. This work is cited as strong evidence that criterion changes can alter perceptual sensitivity and that SDT is inappropriate for investigating complex cognitive processes. The authors' current SDT ideal observer analysis of the model demonstrates that related priming does not directly alter sensitivity and that unrelated priming increases only false-alarm rate, reducing sensitivity. This analysis provides new perspectives on SDT concepts of complex decision processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depth-of-processing effects on priming in stem completion: tests of the voluntary-contamination, conceptual-processing, and lexical-processing hypotheses

Depth-of-processing effects on incidental perceptual memory tests could reflect (a) contamination by voluntary retrieval, (b) sensitivity of involuntary retrieval to prior conceptual processing, or (c) a deficit in lexical processing during graphemic study tasks that affects involuntary retrieval. The authors devised an extension of incidental test methodology--making conjunctive predictions about response times as well as response proportions--to discriminate among these alternatives. They used graphemic, phonemic, and semantic study tasks, and a word-stem completion test with incidental, intentional, and inclusion instructions. Semantic study processing was superior to phonemic study processing in the intentional and inclusion tests, but semantic and phonemic study processing produced equal priming in the incidental test, showing that priming was uncontaminated by voluntary retrieval--a conclusion reinforced by the response-time data--and that priming was insensitive to prior conceptual processing. The incidental test nevertheless showed a priming deficit following graphemic study processing, supporting the lexical-processing hypothesis. Adding a lexical decision to the 3 study tasks eliminated the priming deficit following graphemic study processing, but did not influence priming following phonemic and semantic processing. The results provide the first clear evidence that depth-of-processing effects on perceptual priming can reflect lexical processes, rather than voluntary contamination or conceptual processes.     

In Search of Perceptual Priming in a Semantic Classification Task.

Four experiments tested for perceptual priming for written words in a semantic categorization task. Repetition priming was obtained for low-frequency words when unrelated categorizations were performed at study and test (Experiment 1), but it was not orthographically mediated given that written-to-written and spoken-to-written word priming was equivalent (Experiments 2 and 3). Furthermore, no priming was obtained between pictures and words (Experiment 4), suggesting that the nonorthographic priming was largely phonological rather than semantic. These results pose a challenge to standard perceptual theories of priming that should expect orthographic priming when words are presented in a visual format at study and test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Level of processing affects priming in word fragment completion.

In 4 experiments, Ss studied words under learning conditions that promoted semantic or physical processing. An implicit word fragment completion test was administered (e.g., complete l ph t for elephant). When semantic and physical study conditions were manipulated between Ss (Exps 1 and 3) or within Ss in a blocked fashion (Exps 3 and 4), significant levels of processing (LOP) effects were obtained. When semantic and physical conditions were presented in a mixed list (Exps 2, 3, and 4), the LOP effect was smaller and not significant. A survey of the literature on LOP effects in implicit perceptual tests revealed that priming in these tests was consistently greater in the semantic than physical condition, with reports of statistically significant LOP effects. These findings contradict the widely held notion that LOP does not affect priming in implicit perceptual tests and have implications for contemporary accounts of performance in implicit and explicit measures of memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional sensitization of unconscious cognition: Task sets modulate subsequent masked semantic priming.

According to classical theories, automatic processes are autonomous and independent of higher level cognitive influence. In contrast, the authors propose that automatic processing depends on attentional sensitization of task-congruent processing pathways. In 3 experiments, the authors tested this hypothesis with a modified masked semantic priming paradigm during a lexical decision task by measuring event-related potentials (ERPs): Before masked prime presentation, participants attended an induction task either to semantic or perceptual stimulus features designed to activate a semantic or perceptual task set, respectively. Semantic priming effects on the N400 ERP component, an electrophysiological index of semantic processing, were obtained when a semantic task set was induced immediately before subliminal prime presentation, whereas a previously induced perceptual task set attenuated N400 priming. Across experiments, comparable results were obtained regardless of the difficulty level and the verbal or nonverbal nature of the induction tasks. In line with the proposed attentional sensitization model, unconscious semantic processing is enhanced by a semantic and attenuated by a perceptual task set. Hence, automatic processing of unconscious stimuli is susceptible to top-down control for optimizing goal-related information processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

No negative semantic priming from unconscious flanker words in sight.

In replicating 1 of the within-language conditions of E. Fox's (1996) Experiment 1, the authors confirmed that unattended words presented 2.4° above and below fixation are mostly unavailable to awareness. However, no negative semantic priming was observed in a lexical decision on a probe letter string appearing about 1 s later, which does not replicate Fox's finding. These results are compatible with the hypothesis underlying the present study, according to which positive semantic priming, if any, rather than negative semantic priming is expected in Fox's situation. The reason is that unavailability to awareness of the parafoveal words is not achieved by means of an act of selective inhibition combined with attentional diversion through masking but is achieved simply by means of perceptual degradation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Imaging unconscious semantic priming

Visual words that are masked and presented so briefly that they cannot be seen may nevertheless facilitate the subsequent processing of related words, a phenomenon called masked priming. It has been debated whether masked primes can activate cognitive processes without gaining access to consciousness. Here we use a combination of behavioural and brain-imaging techniques to estimate the depth of processing of masked numerical primes. Our results indicate that masked stimuli have a measurable influence on electrical and haemodynamic measures of brain activity. When subjects engage in an overt semantic comparison task with a clearly visible target numeral, measures of covert motor activity indicate that they also unconsciously apply the task instructions to an unseen masked numeral. A stream of perceptual, semantic and motor processes can therefore occur without awareness.     

Attention and perceptual priming in the perceptual identification task.

Prior research indicates that manipulations of attention during encoding sometimes affect perceptual implicit memory. Two hypotheses were investigated. One proposes that manipulations of attention affect perceptual priming only to the extent that they disrupt stimulus identification. The other attributes reduced priming to the disruptive effects of distractor selection. The role of attention was investigated with a variant of the Stroop task in which participants either read words, identified their color, or did both. Identifying the color reduced priming even when the word was also overtly identified. This result held regardless of whether color and word were presented as a single object (Experiments 1 and 2) or as separate objects (Experiment 4). When participants read and identified a color, the overt order of the responses did not matter; both conditions reduced priming relative to reading alone (Experiment 3). The results provide evidence against the stimulus-identification account but are consistent with the distractor-selection hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Negative priming for obsessive-compulsive checkers and noncheckers.

Negative priming—the slowing of a response to an item that was recently ignored—was investigated in three groups: obsessive-compulsive disorder (OCD) checkers, OCD noncheckers, and nonclinical control participants. All groups performed both a standard negative priming task, selecting targets based on a perceptual feature (i.e., color), and a modified negative priming task, selecting targets based on a semantic feature (i.e., referent size). All three groups demonstrated significant negative priming in both tasks, although the negative priming was much larger in the novel, semantic task than in the common perceptual one. The findings suggest that patients with OCD do not demonstrate impairments in negative priming, contrary to earlier claims (Enright & Beech, 1990, 1993a, 1993b; Enright, Beech, & Claridge, 1995). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Direct and indirect measures of memory for modality in young and older adults.

In 2 experiments, young and older adults demonstrated modality effects of similar magnitude in perceptual identification tasks. That is, both young and older adults demonstrated more repetition priming when study and test modalities matched than when they were different, suggesting that contextual information was equally available across age. However, when asked explicitly to retrieve modality information, older adults were less accurate than young adults. These results constitute evidence for a dissociation between direct and indirect measures of memory for modality information. They call into question hypotheses that memory impairment in old age is due to deficient encoding of contextual information and challenge current accounts of modality effects in repetition priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory priming: Implicit and explicit memory for words and voices.

Five experiments explore priming effects on auditory identification and completion tasks as a function of semantic and nonsemantic encoding tasks and whether speaker's voice is same or different at study and test. Auditory priming was either unaffected by the study task manipulation (Exps 2, 4, and 5) or was less affected than was explicit memory (Exps 1 and 3). Study-to-test changes of speaker's voice had significant effects on priming when white noise masked target items on the identification test (Exps 1 and 2) or the stem-completion test (Exp 5). However, significant voice change effects were observed on priming of completion performance when stems were spoken clearly (Exps 3 and 4). Results are consistent with the idea that a presemantic auditory perceptual representation system plays an important role in the observed priming. Alternative explanations of the presence or absence of voice change effects under different task conditions are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Priming effects in semantic classification tasks.

Six experiments were conducted on priming in semantic classification tasks that allow free play between perceptual and semantic processes. Priming was greatest when words were repeated on the same semantic task at study and test but was absent when repeated words were classified on different semantic tasks (size and man-made; Exp 1). Thus, merely repeating perceptual information is not sufficient to produce priming. Priming was obtained, however, when items on the same semantic task were repeated in different formats (words and pictures; Exp 2). Consistent with stage models of single-word reading, priming was obtained when a semantic classification task was followed by a word form task (i.e., lexical classification or naming) but not when it was preceded by the word form task (Exps 3 and 4). Priming was also found across lexical tasks that both involve the word form (Exp 5) and across classification tasks that refer to the same semantic domain (overall size and relative dimensions; Exp 6). Results suggest that priming is determined by the overlap in the component processes of the study and test tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

New limits to automaticity: Context modulates semantic priming.

It is widely assumed that semantic priming in visual word recognition is automatic when the task requires word-level analysis. The present experiments show that this conclusion is too strong. Whether brief-duration primes facilitated the processing of related targets in lexical decision depended on the context in which the primes were seen. Semantic priming occurred if Ss saw only brief primes (blocked condition) but was minimal if longer primes were presented as well (mixed condition). Converging operations indicate that this modulation of semantic priming reflects operations beyond the lexical level rather than early encoding deficits. Rather than being automatic, semantic priming depends on the context in which a word is read. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exploring the Identification-Production Hypothesis of Repetition Priming in Young and Older Adults.

The identification-production hypothesis of age-related differences in repetition priming predicts reduced priming in older adults on indirect memory measures that require stimulus production (production priming) together with age constancy on indirect measures that require stimulus identification, verification, or classification processes (identification priming). Although some evidence is consistent with this hypothesis, comparisons of identification and production priming in young and older adults often confound stimulus, subject, and dependent measure factors across tasks. Consequently, repetition priming has yet to be assessed in healthy young and healthy older adults using identification and production tasks that control for these factors. The identification-production hypothesis was tested using verb generation as a measure of production priming (Experiments 1-3) and semantic classification (Experiment 1) or semantic verification (Experiments 2 and 3) as the measure of identification priming. Contrary to the identification-production hypothesis, no age-related diminutions in identification or production forms of priming were found. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crossmodal semantic priming by naturalistic sounds and spoken words enhances visual sensitivity.

We propose a multisensory framework based on Glaser and Glaser's (1989) general reading-naming interference model to account for the semantic priming effect by naturalistic sounds and spoken words on visual picture sensitivity. Four experiments were designed to investigate two key issues: First, can auditory stimuli enhance visual sensitivity when the sound leads the picture as well as when they are presented simultaneously? And, second, do naturalistic sounds (e.g., a dog's “woofing”) and spoken words (e.g., /d?g/) elicit similar semantic priming effects? Here, we estimated participants' sensitivity and response criterion using signal detection theory in a picture detection task. The results demonstrate that naturalistic sounds enhanced visual sensitivity when the onset of the sounds led that of the picture by 346 ms (but not when the sounds led the pictures by 173 ms, nor when they were presented simultaneously, Experiments 1-3A). At the same SOA, however, spoken words did not induce semantic priming effects on visual detection sensitivity (Experiments 3B and 4A). When using a dual picture detection/identification task, both kinds of auditory stimulus induced a similar semantic priming effect (Experiment 4B). Therefore, we suggest that there needs to be sufficient processing time for the auditory stimulus to access its associated meaning to modulate visual perception. Besides, the interactions between pictures and the two types of sounds depend not only on their processing route to access semantic representations, but also on the response to be made to fulfill the requirements of the task. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Effects of imagery on perceptual implicit memory tests.

Four experiments demonstrate that imagery can promote priming on perceptual implicit memory tests. When Ss were given words during a study phase and asked to form mental images of corresponding pictures, more priming was obtained on a picture fragment identification test than from a study condition in which Ss performed semantic analyses of words. Imaginal priming of picture fragment identification occurred for recoverable fragments, but not for nonrecoverable fragments. The imagery effect was restricted to the imaged type of material: Imagining pictures (when presented with words) enhanced priming on a picture fragment identification test but not on word fragment completion. Similarly, when pictures were presented, imagining the corresponding words increased priming on word fragment completion but not on picture fragment identification. Overall, results support the hypothesis that imagining engages some of the same mechanisms used in perception and thereby produces priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term repetition priming of briefly identified objects.

The authors provide evidence that long-term memory encoding can occur for briefly viewed objects in a rapid serial visual presentation list, contrary to claims that the brief presentation and quick succession of objects prevent encoding by disrupting a memory consolidation process that requires hundreds of milliseconds of uninterrupted processing. Subjects performed a search task in which each item was presented for only 75 ms. Nontargets from the search task generated priming on 2 subsequent indirect memory tests: a search task and a task requiring identification of visually masked objects. Additional experiments revealed that information encoded into memory for these nontargets included perceptual and conceptual components, and that these results were not due to subjects maintaining items in working memory during list presentation. These results are consistent with recent neurophysiological evidence showing that stimulus processing can occur at later stages in the cognitive system even when a subsequent new stimulus is presented that initiates processing at earlier stages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact perceptual memory in the absence of conscious memory.

Declarative memory enables conscious recollection of the past and has been proposed to be distinct from priming, a perceptual form of memory that operates nonconsciously and improves the ability to detect or identify recently presented stimuli. Yet, it has been difficult to obtain unambiguous evidence for the independence of declarative memory and priming. The authors report the first demonstration, using matched tests, of fully intact perceptual memory (priming) in a profoundly amnesic patient (E.P.), despite at-chance recognition memory. The priming and recognition tests included tests that were matched with respect to test materials, length of the study and test lists, and the kind of cues available at test. Priming appears to reflect neural changes within perceptual processing systems that occur before information reaches the brain systems that transform visual perception into conscious visual memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)