Masked and unmasked priming in schizophrenia

Dehaene et al. (2003) showed an absence of conscious, but not masked, conflict effects when patients with schizophrenia performed a number-categorisation priming task. We aimed to replicate these influential results using a different word-categorisation priming task. Counter to Dehaene et al.’s findings, 21 patients and 20 healthy controls showed similar congruence effects for both masked and visible primes. Within patients, a reduced congruence effect for visible primes associated with longer duration of illness and more severe behavioural disorganisation. Patients, unlike controls, were no slower to respond to targets that followed visible compared to masked primes. Conscious conflict effects on priming tasks are not universally reduced in schizophrenia but may associate with chronicity and behavioural disorganisation. That patients were no slower when the preceding primes were clearly visible accords with evidence elsewhere that information processing in schizophrenia is driven more by immediate conscious experience and constrained less by prior events.     

Masked repetition priming using magnetoencephalography

Masked priming is used in psycholinguistic studies to assess questions about lexical access and representation. We present two masked priming experiments using MEG. If the MEG signal elicited by words reflects specific aspects of lexical retrieval, then one expects to identify specific neural correlates of retrieval that are sensitive to priming. To date, the electrophysiological evidence has been equivocal. We report findings from two experiments. Both employed identity priming, where the prime and target are the same lexical item but differ in case (NEWS-news). The first experiment used only forward masking, while the prime in the second experiment was both preceded and followed by a mask (backward masking). In both studies, we find a significant behavioral effect of priming. Using MEG, we identified a component peaking approximately 225 ms post-onset of the target, whose latency was sensitive to repetition. These findings support the notion that properties of the MEG response index specific lexical processes and demonstrate that masked priming can be effectively combined with MEG to investigate the nature of lexical processing.     

Masked orthographic priming in bilingual word recognition

Two lexical decision experiments tested the influence of briefly presented orthographically related primes on target word recognition in bilinguals. The prime stimuli were high-frequency words either from the same language as that of the target or from the other language known by the bilingual subjects. When the prime and target were from the same language, orthographically related primes systematically inhibited target word recognition, whereas orthographically dissimilar primes did not. When the prime and target were words from different languages, the amount of inhibition increased as a function of subjects’ level of proficiency in the prime word’s language, with highly proficient bilinguals showing practically equivalent amounts of within and across language inhibitory priming. These results strongly suggest that a printed string of letters can simultaneously activate lexical representations in both of the bilingual’s languages (insofar as these share the same alphabet), even when subjects are performing a monolingual task.     

Masked partial priming of letter perception

In three experiments testing 178 subjects, letter targets were preceded by briefly presented, pattern-masked primes formed by deleting pixels in a larger or smaller version of the target stimulus. In Experiment 1A (alphabetic decision)and Experiment 1B (letter naming) a slight advantage was observed for global primes (alternate pixels deleted) compared with junction primes (midsegment information removed). This advantage was stronger at 50 ms prime exposures than at 30 ms exposures in the naming task. In Experiment 2 (letter naming), midsegment primes (with junction information removed) produced faster latencies than did junction primes. This result was replicated in a third experiment and was shown to be independent of target letter case and the relative size of prime and target stimuli. The same midsegment and junction primes did not facilitate performance compared to neutral primes in the alphabetic decision task. These results suggest that masked partial priming of letter naming can be usefully applied to the study of basic processes in letter perception.     

Masked repetition and phonological priming in picture naming

We report a series of picture naming experiments in which target pictures were primed by briefly presented masked words. Experiment 1 demonstrates that the prior presentation of the same word prime (e.g.,rose-rose) facilitates picture naming independently of the target’s name frequency. In Experiment 2, primes that were homophones of picture targets (e.g.,rows-rose) also produced facilitatory effects compared with unrelated controls, but priming was significantly larger for targets with low-frequency names relative to targets with high-frequency names. In Experiment 3, primes that were higher frequency homophones of picture targets produced facilitatory effects compared with identical primes. These results are discussed in relation to different accounts of the effects of masked priming in current models of picture naming.     

Masked emotional priming beyond global valence activations

An immense body of research demonstrates that emotional facial expressions can be processed unconsciously. However, it has been assumed that such processing takes place solely on a global valence-based level, allowing individuals to disentangle positive from negative emotions but not the specific emotion. In three studies, we investigated the specificity of emotion processing under conditions of limited awareness using a modified variant of an affective priming task. Faces with happy, angry, sad, fearful, and neutral expressions were presented as masked primes for 33 ms (Study 1) or 14 ms (Studies 2 and 3) followed by emotional target faces (Studies 1 and 2) or emotional adjectives (Study 3). Participants' task was to categorise the target emotion. In all three studies, discrimination of targets was significantly affected by the emotional primes beyond a simple positive versus negative distinction. Results indicate that specific aspects of emotions might be automatically disentangled in addition to valence, even under conditions of subjective unawareness.     

Masked suffix priming and morpheme positional constraints

Although masked stem priming (e.g., dealer–DEAL) is one of the most established effects in visual word identification, it is less clear whether primes and targets sharing a suffix (e.g., kindness–WILDNESS) also yield facilitation. In a new take on this issue, we show that prime nonwords facilitate lexical decisions to target words ending with the same suffix (sheeter–TEACHER) compared to a condition where the critical suffix was substituted by another one (sheetal–TEACHER) or by an unrelated nonmorphological ending (sheetub– TEACHER). We also show that this effect is genuinely morphological, as no priming emerged in noncomplex items with the same orthographic characteristics (sportel–BROTHEL vs. sportic–BROTHEL vs. sportur–BROTHEL). In a further experiment, we took advantage of these results to assess whether suffixes are recognized in a position-specific fashion. Masked suffix priming did not emerge when the relative order of stems and suffixes was reversed in the prime nonwords—ersheet did not yield any time saving in the identification of teacher as compared to either alsheet or obsheet. We take these results to show that –er was not identified as a morpheme in ersheet, thus indicating that suffix identification is position specific. This conclusion is in line with data on interference effects in nonword rejection and strongly constrains theoretical proposals on how complex words are identified. In particular, because these findings were reported in a masked priming paradigm, they suggest that positional constraints operate early, most likely at a prelexical level of morpho-orthographic analysis.     

Masked emotional priming beyond global valence activations

An immense body of research demonstrates that emotional facial expressions can be processed unconsciously. However, it has been assumed that such processing takes place solely on a global valence-based level, allowing individuals to disentangle positive from negative emotions but not the specific emotion. In three studies, we investigated the specificity of emotion processing under conditions of limited awareness using a modified variant of an affective priming task. Faces with happy, angry, sad, fearful, and neutral expressions were presented as masked primes for 33 ms (Study 1) or 14 ms (Studies 2 and 3) followed by emotional target faces (Studies 1 and 2) or emotional adjectives (Study 3). Participants’ task was to categorise the target emotion. In all three studies, discrimination of targets was significantly affected by the emotional primes beyond a simple positive versus negative distinction. Results indicate that specific aspects of emotions might be automatically disentangled in addition to valence, even under conditions of subjective unawareness.     

Masked syllable priming of English nouns.

This study investigates the role of sublexical units in the phonological encoding of English single-word production in a word-naming task (Experiment 1) and a picture-naming task (Experiment 2). Targets corresponded to bisyllabic English nouns with word-initial stress which varied on the structure of their first syllable: CV (e.g., pi.lot), CVC (e.g., pic.nic), or CV[C] (e. g., pi[ll]ow).1 Targets were preceded by a visually masked prime that either matched their first syllable (e.g., pi%%% - pi.lot) or that was one segment longer (e.g., pil%% - pi.lot) or shorter (e.g., pi%%%% - pic.nic) than the first syllable. Response times were compared to a neutral control condition (e.g., %&$%% - pi.lot) to measure the priming effects (either facilitation or inhibition). Results showed significant facilitation for both the CV and the CVC conditions. However, contrary to previous findings, there was no interaction between the syllabic structure of the prime and the target.     

Masked constituent letter priming in an alphabetic decision task

Abstract

The experiments presented here were designed to test whether the prior presentation of a letter in a word, nonword or a string of Xs facilitates the subsequent identification of this letter. Using briefly presented masked primes, clear facilitatory constituent priming effects were obtained in an alphabetic decision task (letter/non-letter classification) when prime letters were flanked by Xs, but the effects disappeared or were greatly reduced when the prime letter formed part of a consonant array (nonword primes). Evidence for word-letter constituent priming was also obtained but almost only for word-initial letten. These facilitatory constituent priming effects were strongest when the target letter was embedded in a string of hash marks and occupied the same relative position in this string as the prime letter in the prime string. The mediating role of letter representations in word recognition and the position-specific coding of character arrays are discussed in the light of these results.     

Masked translation priming effects with low proficient bilinguals

Non-cognate masked translation priming lexical decision studies with unbalanced bilinguals suggest that masked translation priming effects are asymmetric as a function of the translation direction (significant effects only in the dominant [L1] to nondominant [L2] language translation direction). However, in contrast to the predictions of most current accounts of masked translation priming effects, bidirectional effects have recently been reported with a group of low proficient bilinguals Duyck & Warlop 2009 (Experimental Psychology 56:173–179). In a series of masked translation priming lexical decision experiments we examined whether the same pattern of effects would emerge with late and low proficient Greek (L1)–Spanish (L2) bilinguals. Contrary to the results obtained by Duyck and Warlop, and in line with the results found in most studies in the masked priming literature, significant translation priming effects emerged only when the bilinguals performed the task with L1 primes and L2 targets. The existence of the masked translation priming asymmetry with low proficient bilinguals suggests that cross-linguistic automatic lexico-semantic links may be established very early in the process of L2 acquisition. These findings could help to define models of bilingualism that consider L2 proficiency level to be a determining factor.     

Masked inhibitory priming in english: evidence for lexical inhibition

Predictions derived from the interactive activation (IA) model were tested in 3 experiments using the masked priming technique in the lexical decision task. Experiment 1 showed a strong effect of prime lexicality: Classifications of target words were facilitated by orthographically related nonword primes (relative to unrelated nonword primes) but were inhibited by orthographically related word primes (relative to unrelated word primes). Experiment 2 confirmed IA's prediction that inhibitory priming effects are greater when the prime and target share a neighbor. Experiment 3 showed a minimal effect of target word neighborhood size (N) on inhibitory priming but a trend toward greater inhibition when nonword foils were high-N than when they were low-N. Simulations of 3 different versions of the IA model showed that the best fit to the data is produced when lexical inhibition is selective and when masking leads to reset of letter activities.     

Masked orthographic priming: The effect of prime-target legibility

The occurrence of extensive orthographic form-priming may provide reasons for preferring connectionist-type models over table-lookup (algorithmic) ones. Short-term masked priming procedures, using either tachistoscopic identification or lexical decision as the response measure, have shown consistent form-priming effects. Unfortunately, different results emerge depending on the procedure used. With the identification procedure, almost any orthographic overlap between prime and target is sufficient for priming to occur, but with the lexical decision procedure, form priming effects are much more limited in scope. The experiments reported here show that accuracy in the masked identification paradigm is influenced by the legibility of the target stimulus when superimposed on an image of the prime, even though there is no orthographic overlap between the two stimuli. Yet for the lexical decision version of the masked priming procedure there is no difference in latency or error rate as a function of legibility. It is further shown that the presence or absence of the legibility effect has little to do with the nature of the task required of the subject, but is instead a function of the duration of the target--i.e. the legibility effect depends on having the prime and the target both displayed rapidly, and both masked. Failing to take legibility effects into account may lead to problems in interpreting the exact extent of form-priming effects in studies that use the identification procedure.     

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.     

Masked repetition and phonological priming within and across modalities

Lexical decision latencies to word targets presented either visually or auditorily were faster when directly preceded by a briefly presented (53-ms) pattern-masked visual prime that was the same word as the target (repetition primes), compared with different word primes. Primes that were pseudohomophones of target words did not significantly influence target processing compared with unrelated primes (Experiments 1-2) but did produce robust priming effects with slightly longer prime exposures (67 ms) in Experiment 3. Like repetition priming, these pseudohomophone priming effects did not interact with target modality. Experiments 4 and 5 replicated this general pattern of effects while introducing a different measure of prime visibility and an orthographic priming condition. Results are interpreted within the framework of a bimodal interactive activation model.     

Masked priming effect reflects evidence accumulated by the prime

In the same–different match task, masked priming is observed with the same responses but not different responses. Norris and Kinoshita's (2008) Bayesian reader account of masked priming explains this pattern based on the same principle as that explaining the absence of priming for nonwords in the lexical decision task. The pattern of priming follows from the way the model makes optimal decisions in the two tasks; priming does not depend on first activating the prime and then the target. An alternative explanation is in terms of a bias towards responding “same” that exactly counters the facilitatory effect of lexical access. The present study tested these two views by varying both the degree to which the prime predicts the response and the visibility of the prime. Unmasked primes produced effects expected from the view that priming is influenced by the degree to which the prime predicts the response. In contrast, with masked primes, the size of priming for the same response was completely unaffected by predictability. These results rule out response bias as an explanation of the absence of masked priming for different responses and, in turn, indicate that masked priming is not a consequence of automatic lexical access of the prime.     

Masked priming effects in semantic categorization are independent of category size

The question whether subliminal primes can activate their semantic meaning or not is still of interest today. Three different competing theories have tried to account for the often inconsistent research results: The semantic categorization hypothesis, the direct motor specification hypothesis, and the category search model. The present study aimed to shed light on these different points of view by examining the role of category size in response congruency effects when novel primes are used. Three experiments were conducted and a transparent pattern of results emerged: Significant priming effects were obtained across different tasks, irrespective of category size and irrespective of stimulus set size. The findings are discussed in terms of the three theoretical frameworks. It becomes clear that the present results provide strong evidence in favor of the semantic categorization hypothesis, which assumes semantic processing of subliminal primes.