Locus of inhibition effects in the priming of lexical decisions: pre- or postlexical access?

The lexical decision task has been employed to investigate the effects of semantic context on word recognition. A frequent finding from the task is that “word” responses are slower when the target is preceded by an unrelated word than when it is preceded by a neutral stimulus. This inhibition effect has been interpreted as indicating that the unrelated prime interferes with word-recognition processes operating on the target. In three experiments, the effects of unrelated primes were compared for a lexical decision and word naming task. Although large inhibition effects were found for the lexical decision task in all experiments, no inhibition effects were observed for the naming task. The results are interpreted as demonstrating that inhibition effects in the lexical decision task are not on recognition processes; rather they are located at processes operating after recognition of the target has occurred.     

The unattended speech effect: perception or memory?

Broadbent (1983) has suggested that the influence of unattended speech on immediate serial recall is a perceptual phenomenon rather than a memory phenomenon. In order to test this, subjects were required to classify visually presented pairs of consonants on the basis of either case or rhyme. They were tested both in silence and against a background of continuous spoken Arabic presented at 75 dB(A). No effect of unattended speech was observed on either the speed or accuracy of processing. A further study required subjects to decide whether visually presented nonwords were homophonous with real words. Again, performance was not impaired by unattended speech, although a clear effect was observed on an immediate serial memory task. Our results give no support to the perceptual interpretation of the unattended speech effect.     

Homotopic callosal inhibition in hemispheric priming: A test of cook’s topographical inhibitory model

This study set out to evaluate Cook’s (1986) topographical inhibitory model of language processing in the hemispheres. The model employs the neurophysiological mechanism of homotopic callosal inhibition to explain recent findings which suggest that the left hemisphere processes denotative meaning, while the right hemisphere specializes in connotative meaning. Specific predictions in relation to lateralized priming phenomena were derived from the model. The first experiment tested the prediction that word repetition and denotative priming would facilitate responses to right visual field targets, while connotative priming would favour the left visual field. None of these predictions were confirmed. A second experiment modified in a number of ways, provided a more extensive test of the predictions but produced essentially the same result. It was concluded that no evidence could be obtained to support the topographical inhibitory model. Instead, the results extend previous findings by suggesting that associative priming has more or less equivalent effects in each hemisphere, provided the interval between prime and target is sufficiently long.     

Does negative priming imply preselective identification of irrelevant stimuli?

Responses to recently ignored stimuli are often slower than responses to new stimuli (negative priming). This slowing is thought to imply that the irrelevant stimuli were identified before the relevant stimuli were selected. The slowing may, however, reflect processing that occurred after the selection process had already begun. In two experiments, the opportunity for preselective identification of irrelevant stimuli was eliminated by presenting the irrelevant stimuli late within the trial. Negative priming failed to occur under these conditions.     

The masked onset priming effect in naming: computation of phonology or speech planning?

We investigated factors that modulate the presence of the masked onset priming effect in three naming experiments. In Experiment 1, we showed that the masked onset priming effect is found with regular words, but not with exception words, replicating the finding reported by Forster and Davis (1991). In Experiment 2, we used the conditional naming task in which words are mixed with nonwords and participants are instructed to name the item only if it is a word. The masked onset priming effect was eliminated in this experiment, but the regularity effect remained. In Experiment 3, regular and irregular words were mixed randomly, rather than in separate blocks as in Experiment 1. This reduced the size of the regularity effect, and the masked onset priming effect was again absent. We argue that these results, taken as a whole, are better interpreted within the view that the masked onset priming effect has its origin in the preparation of a speech response, rather than within the original dual-route interpretation proposed by Forster and Davis.     

Does negative priming reflect inhibitory mechanisms? A review and integration of conflicting views

Negative priming has traditionally been viewed as a reflection of an inhibitory mechanism of attention. However, recent accounts have suggested that negative priming does not reflect inhibitory mechanisms. Rather, slowed reaction times on negative priming trials are either due to retrieval of incompatible response tags or of mismatching perceptual information, or due to extra processes needed to distinguish past from present information. In contrast, it is proposed that there is no firm evidence to discount inhibition models. In fact, although retrieval processes can be implicated in negative priming effects, understanding of these requires consideration of the inhibitory processes involved in selecting information for goal-directed behaviour.     

Short-term aftereffects of response inhibition: repetition priming or between-trial control adjustments?

Repetition priming and between-trial control adjustments after successful and unsuccessful response inhibition were studied in the stop-signal paradigm. In 5 experiments, the authors demonstrated that response latencies increased after successful inhibition compared with trials that followed no-signal trials. However, this effect was found only when the stimulus (Experiments 1A-4) or stimulus category (Experiment 3) was repeated. Slightly different results were found after trials on which the response inhibition failed. In Experiments 1A, 2, and 4, response latencies increased after unsuccessful inhibition trials compared with after no-inhibition trials, and this happened whether or not the stimulus repeated. Based on these results, we suggest that the aftereffects of successful response inhibition are primarily due to repetition priming, although there was evidence for between-trial control adjustments when inhibition failed.     

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.     

Revisiting the prime–probe contextual similarity effect on negative priming: The impact of cue variability

In previous studies on negative priming, the effect of prime–probe contextual similarity was not stable. On occasions, negative priming was greater when similar rather than different contexts were presented in a prime and a probe trial; however, at other times, negative priming was not affected by such manipulation. The current study demonstrates that the effect of contextual similarity can be optimised when cue variability is high. Cue variability was manipulated between-subject across Experiments 1a and 1b and as a within-subject variable in Experiment 2. Symbols were presented as contextual cues. The results indicated that when cue variability was high, the prime–probe contextual similarity effect was observed on negative priming; however, when cue variability was low, the contextual similarity effect and the negative priming effect were absent.     

The mechanism of priming: episodic retrieval or priming of pop-out?

Previous studies indicate that priming affects attentional processes, facilitating processes of target detection and selection on repetition trials. However, the results are so far compatible with two different attentional views that propose entirely different mechanisms to account for priming. The priming of pop-out hypothesis explains priming by feature weighting processes that lead to more frequent selections of nontarget items on switch trials. According to the episodic retrieval account, switch trials conversely lead to temporal delays in retrieving priority rules that specify the target. The results from two eye tracking experiments clearly favour the priming of pop-out hypothesis: Switching the target and nontarget features leads to more frequent selection of nontargets, without affecting the time-course of saccades to a great extent. The results from two more control experiments demonstrate that the same results can be obtained in a visual search task that allows only covert attention shifts. This indicates that eye movements can reliably indicate covert attention shifts in visual search.     

Is inhibition of return a reflexive effect?

The inhibition of return (IOR) phenomenon is routinely considered an effect of reflexive attention because the paradigm used to generate IOR employs peripheral cues that are uninformative as to where a target will appear. Because the cues are spatially unreliable it is thought that there is no reason for attention to be committed volitionally to them, and hence, the IOR effect is considered reflexive. What has been generally overlooked, however, is that the cues provide reliable temporal information as to when a target will occur. This predictive information is used by participants to prepare volitionally for when a target is likely to appear. We investigated whether the IOR effect is a product of the volitional application of attention to peripheral cues for the use of their temporal information. To test this idea we rendered the temporal information provided by peripheral cues unreliable. While this eliminated participants using the cues volitionally, it did not abolish the IOR phenomenon. These data demonstrate two new findings. First, the IOR effect is fundamentally a reflexive phenomenon. Second, when peripheral cues are not used volitionally, the IOR effect is attenuated. Together, the present findings indicate that the IOR effect can be modulated by volitional (top-down) processes but it is not the product of them. We argue that an intimate link between fronto-parietal regions and the superior colliculus provide a functional neural mechanism for this volitional effect to impact IOR.     

Can the location negative priming process operate in a proactive manner?

The location negative priming (NP) effect refers to the fact that the processing of a current target stimulus (probe trial) is delayed when it appears at a location that has recently contained a distractor event (prime trial), relative to when it occurs at a previously unoccupied position. One view is that the process causing the NP effect involves the inhibition of the internal representation of the prime-distractor event, and that the future processing of target stimuli that involve this event are prolonged because this distractor inhibition is persistent. In this study, we examined the possibility that the NP process (inhibition) could act proactively; specifically asking whether inhibition could be allocated to a location merely predicted to hold a future distractor event. To do this, we cued the probe distractor's location using an otherwise traditional location NP paradigm. No evidence of a proactive NP process was obtained. Probe-trial target latency was the same whether it appeared at the cued distractor location or at a new location, but was delayed when it occupied the prime-distractor location (NP effect). The location NP process is seemingly a reactive one, applying inhibition only when an actual distractor is present, much as past theories have implied.     

The plausibility effect: Lexical priming or sentential processing?

Five experiments are reported that investigated whether the plausibility effect is caused by lexical priming resulting from the higher proportion of related words in plausible than in implausible sentences. In Experiment 1, a plausibility effect was demonstrated that was entirely attributable to the way in which lexical items were combined rather than to the properties of individual lexical items. In Experiment 2, the content words from the sentences used in Experiment 1 were shown to produce a similar reaction-time difference in a task in which syntactic processing was disrupted, supporting a lexical priming explanation of the plausibility effect. However, Experiments 3 and 4 demonstrated that, in another task less prone to task-specific strategies but sensitive to plausibility, the disruption of syntactic processing eliminated the effect. In Experiment 5, it was shown that when lexical priming was eliminated, a plausibility effect still occurred. Thus, two separate lines of evidence suggested that the plausibility effect cannot be fully explained in terms of lexical priming.     

Auditory spatial negative priming: What is remembered of irrelevant sounds and their locations?

The categorization and identification of previously ignored visual or auditory stimuli is typically slowed down—a phenomenon that has been called the negative priming effect and can be explained by the episodic retrieval of response-inadequate prime information and/or an inhibitory model. A similar after-effect has been found in visuospatial tasks: participants are slowed down in localizing a visual stimulus that appears at a previously ignored location. In the auditory modality, however, such an after-effect of ignoring a sound at a specific location has never been reported. Instead, participants are impaired in their localization performance when the sound at the previously ignored location changes identity, a finding which is compatible with the so-called feature-mismatch hypothesis. Here, we describe the properties of auditory spatial in contrast to visuospatial negative priming and report two experiments that specify the nature of this auditory after-effect. Experiment 1 shows that the detection of identity-location mismatches is a genuinely auditory phenomenon that can be replicated even when the sound sources are invisible. Experiment 2 reveals that the detection of sound-identity mismatches in the probe depends on the processing demands in the prime. This finding implies that the localization of irrelevant sound sources is not the inevitable consequence of processing the auditory prime scenario but depends on the difficulty of the target search process among distractor sounds.     

Where has all the inhibition gone? Insights from electrophysiological measures into negative priming without probe distractors

Responses to probe targets that have been distractors in a prime display are slower than responses to unrepeated stimuli, a finding labeled negative priming (NP). However, without probe distractors the NP effect usually diminishes. The present study is the first to investigate ERP correlates of NP without probe distractors to shed light on the processes underlying NP. Based on existing findings in the field, we analyzed two ERP correlates that have been associated with the visual NP effect so far, namely the N200 and the P300. As expected, no behavioral NP effect as well as no N200 modulation emerged. However, the P300 component was enhanced when a prime distractor was repeated as the probe target. This effect is interpreted as reflecting automatic retrieval of the prime episode occurring independently of the presence of probe distractors.     

Specificity of auditory implicit and explicit memory: Is perceptual priming for environmental sounds exemplar specific?

Previous research (Stuart & Jones, 1995) has suggested that identification of environmental sounds may be mediated by abstract sound recognition units. This article reports the results of four repetition priming experiments that find evidence to the contrary. Participants attempted to identify environmental sounds from the initial sound stems (Experiments 1 and 2) or when the sounds were embedded in white noise (Experiments 3 and 4). Repetition of an identical exemplar sound led to more priming than did exposure to a different exemplar, provided that the perceptual difference between the two different exemplars was sufficiently large. Such an exemplar specificity effect was independent of the depth of prior encoding. A similar exemplar specificity effect was also found in explicit stem-cued recall (Experiments 1 and 2) and recognition (Experiment 3). Depth of encoding dissociated performance on tests of repetition priming and explicit memory. These results suggest that a significant amount of specific information is remembered, both implicitly and explicitly, to characterize individual exemplars of a sound category.     

Center-surround or spreading inhibition: which mechanism caused the negative effect from repeated masked semantic primes?

In the paradigm of repeated masked semantic priming (Wentura & Frings. 2005), prime and mask are repeatedly and rapidly interchanged. Using this technique in a semantic priming task with category labels as primes and category exemplars as targets (related, e.g.. BIRD - swan --> BIRD - finch; unrelated, e.g., BIRD - lily --> FRUIT - finch), Wentura and Frings found a negatively signed priming effect. Here we used the repeated masking technique with category exemplars as targets and primes (i.e., identity priming) for analyzing, whether this effect reflects center-surround or spreading inhibition. If the repeated masked technique reflects spreading inhibition, a negative effect should also appear for identity priming. In contrast, a center-surround approach would predict a positive effect. In accordance with the latter hypothesis, we found a significant positive effect in identity priming (Experiment 1a) and significant difference to the negatively signed semantic priming effect when primes were category labels (Experiment 1b). This is indicative of the repeated masked semantic priming effect being a negatively signed semantic priming effect due to a center-surround mechanism.     

Social priming of dyslexia and reduction of the Stroop effect: What component of the Stroop effect is actually reduced?

Recently, Goldfarb, Aisenberg, and Henik (2011) showed that in a manual format of the Stroop task, dyslexia priming eliminates the normal magnitude of the interference-based Stroop-like findings otherwise exhibited by individuals participating in such research. Goldfarb et al. (2011) consequently concluded that the effect of word reading in a Stroop task (i.e., one automatic behavior) can be effectively controlled through an automatic instruction “do not read” (i.e., another automatic behavior). The present study further investigated these ideas by examining when and how dyslexia priming controls different processes involved in a Stroop task. To this end, the original finding was first replicated (Experiment 1) and subsequently extended to the vocal (instead of manual) response modality to examine whether previously reported eliminations of the Stroop effect persist with this response format (i.e., format producing larger Stroop effects). Since past work (e.g., Augustinova & Ferrand, 2012a; Brown, Joneleit et al., 2002; Ferrand & Augustinova, 2013) had suggested that various interventions were likely to reduce (rather than eliminate) the interference-based Stroop-like findings with vocal responses, a further aim of these experiments was to identify the component of these findings that dyslexia priming actually reduces. To this end, the effects of this intervention were examined in a more fine-grained variant of the Stroop task that distinguished between interference resulting from task-irrelevant processes involved in computing the lexical and semantic representations of the word (i.e., a written distractor to ignore) and task-relevant processes involved in the selection of a response (i.e., a color target to name) that are both involved in this task. In line with our past work (e.g., Augustinova & Ferrand, 2012a; Ferrand & Augustinova, 2013), the results of two experiments (Experiments 2 and 3) showed that in the vocal format, dyslexia priming reduces but does not eliminate the normal magnitude of the interference-based Stroop-like findings and that this reduction is solely due to the control of processes involved in the selection of a response (i.e., a color target to name) – processes that are known to be controllable in this format (Ferrand & Augustinova, 2013). Given that in this format, dyslexia priming had no effect on task-irrelevant processes involved in computing the lexical and semantic representations of a written distractor to be ignored – processes that are known to be automatic – further implications for the control of automatic processes via dyslexia priming are considered and an interpretation in terms of a unitary control mechanism for both the manual and vocal formats is proposed.