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.     

Perceptual learning can reverse subliminal priming effects

Masked primes presented prior to a target can result in inverse priming (i.e., benefits on trials in which the prime and the target are mapped onto opposite responses). In five experiments, time-of-task effects on subliminal priming of motor responses were investigated. First, we replicated Klapp and Hinkley's (2002) finding that the priming effect is initially straight (i.e., it benefits congruent trials, in which the prime and targets are mapped onto the same response) or absent, and only later reverses (i.e., faster responses in incongruent than in congruent trials). We show that the presentation of the mask plays a crucial role in this reversal and that the reversal occurs later if the mask pattern is very complex. We suggest that perceptual learning improves the recognition of task-relevant features. Once recognized, these features can trigger the preparation of the alternative response and/or inhibit the prime-activated response. These findings support an active role of the mask in priming.     

Response priming with apparent motion primes

Response priming refers to the finding that a prime stimulus preceding a target stimulus influences the response to the following target stimulus. Typically, responses are faster and more accurate if the prime calls for the same response as the target (i.e., compatible trials), as compared with the situation where primes and targets trigger different responses (i.e., incompatible trials). However, the effect depends on presentational and temporal parameters such as the stimulus onset asynchrony (SOA) of prime and target, or prime duration. Until now, the special role of moving stimuli was largely ignored. In the present research, experiments were conducted using clearly visible moving dots as primes and static arrows as targets. Essentially, with short SOAs up to 200 ms, participants responded faster to compatible targets. In contrast, with SOAs above 200 ms, participants responded faster to incompatible targets. The results were compared with response priming with static primes. Here, a different pattern of results emerged, with faster responses to compatible than incompatible targets at a long SOA of 300 ms. Overall, the experiments provide evidence for the existence of an inhibitory mechanism in action control when (distracting) motion stimuli are present. Results could be explained with slight changes to different accounts of negative response priming effects, as well as theories of attention.     

Depth of facial expression processing depends on stimulus visibility: Behavioral and electrophysiological evidence of priming effects

Participants performed a priming task during which emotional faces served as prime stimuli and emotional words served as targets. Prime-target pairs were congruent or incongruent, and two levels of prime visibility were obtained by varying the duration of the masked primes. To probe a neural signature of the impact of the masked primes, lateralized readiness potentials (LRPs) were recorded over motor cortex. In the high-visibility condition, responses to word targets were faster when the prime-target pairs were congruent than when they were incongruent, providing evidence of priming effects. In line with the behavioral results, the electrophysiological data showed that high-visibility face primes resulted in LRP differences between congruent and incongruent trials, suggesting that prime stimuli initiated motor preparation. Contrary to the above pattern, no evidence for reaction time or LRP differences was observed in the low-visibility condition, revealing that the depth of facial expression processing is dependent on stimulus visibility.     

Cross-language negative priming remains intact,while positive priming disappears: evidence for two sources of selective inhibition

In the current experiments, within- and between-language primed lexical decision tasks with Twi-English bilinguals were used. The aim was to explore the priming effects produced by attended and ignored words, in an effort to draw theoretical and empirical parallels and differences between the mechanisms of excitation and inhibition and to isolate the different circumstances in which these mechanisms operate in bilingual language processing. In the within-language (Twi) experiment, facilitatory (positive) priming resulted when a prime word and subsequent probe target word were identical, whereas delayed decisions to probe targets (negative priming) ensued when the ignored prime word was conceptually identical to the subsequent probe target word. In contrast, while the between-language (Twi-English) experiments replicated the ignored repetition negative priming effect, no evidence of positive priming was observed. These between-language findings undermine episodic retrieval models of selective attention that discount inhibitory processes in negative priming paradigms. Instead, our findings substantiate inhibition-based accounts by showing that there are two sources of inhibition operating at the local word and global language levels of abstraction. The findings also support bilingual language representations in which the words of the two languages are integrated.     

Time course of free-choice priming effects explained by a simple accumulator model

Unconscious visual stimuli can be processed by human observers and modulate their behavior. This has been shown for masked prime stimuli that influence motor responses to subsequent target stimuli. Beyond this, masked stimuli can also affect participants' behavior when they are free to choose one of two response alternatives. This finding demonstrates that an apparently free-choice between alternative behaviors can be subject to influences that are outside of awareness. We report three experiments which exhibit that the temporal dynamic of free-choice priming effects corresponds to that of forced-choice priming effects. Forced-choice priming effects were relatively robust against variations of prime stimuli but sensitive to physical features of target stimuli. Free-choice priming effects, in contrast, depended largely on the stimulus-response compatibility of the prime. A simple accumulator model which accounts for forced-choice response priming can also explain free-choice priming effects by the assumption that unconscious stimuli can initiate motor responses when participants are engaged in a speeded choice-reaction time task. According to our analyses free-choice priming results from a response selection mechanism which integrates conscious and unconscious information from external, stimulus driven sources and also from internal sources.     

Oscillations in motor priming: positive rebound follows the inhibitory phase in the masked prime paradigm

Masked stimuli can cause partial motor activation and prime responses to subsequent stimuli. Under certain conditions, a biphasic pattern appears, such that positive priming precedes a negative phase, which has been interpreted as evidence of an inhibitory mechanism that suppresses the motor activity caused by the prime. In this article, the authors report evidence for a further reversal in priming: In two experiments, the authors found that the negative compatibility effect was followed by a small but repeatable positive priming effect at an interval of approximately 500 ms between prime and target. Thus, masked primes appear to produce a triphasic pattern of priming, which is consistent with the notion that oscillation between facilitation and inhibition may be a fundamental property of the competitive interactions between response alternatives in the motor system.     

Semantic priming and identification of near threshold primes in a lexical decision task

Three experiments examined both the impact of semantic analysis of 50-msec, masked visual primes on a target response and the impact of semantic analysis of the target on a prime response. The first two experiments used a prime-target interval of 1000 msec. In Experiment 1, subjects reported the identity of each prime: (a) after a lexical decision about the target, (b) both before and after a lexical decision, or (c) after a target detection response. Prime report after both types of target response showed retroactive priming in which report was facilitated by related targets and inhibited by unrelated targets. Analyses of lexical decision latency and accuracy conditionalized on prime report showed that semantic priming was restricted to reported related primes. In Experiment 2, subjects made no overt response to the primes. Priming was conditionalized on recognition of the primes on a subsequent test. The pattern was the same as Experiment 1: There was priming only for recognized primes; recognition memory showed a pattern consistent with retroactive priming. Experiment 3 also conditionalized priming on recognition performance but used a prime-target interval of only 250 msec. Again, semantic priming was found only for recognized primes, and recognition memory revealed retroactive priming. Retroactive priming indicates an interdependency between prime and target processing that needs to be incorporated into models of semantic priming.     

Priming of future States in complex motor skills

The ability to anticipate future states of perceived actions is an important faculty for motor control and the generation of coordinated social interaction. Here, we studied whether the perception of a static posture of a complex movement automatically activates representations of future states of this particular movement event. We did this by using a priming paradigm with photographs of a high-jump movement. Participants judged whether a picture depicted a posture from the approach or flight phase of that movement. To evaluate expertise-dependent effects of priming, non-athletes and athletes were compared. Results revealed faster responding when prime and target pictures were assigned to the same motor response (response priming), and when the temporal order of prime and target matched the temporal order of the depicted postures in a real high jump (temporal-order priming). Whereas experts showed a temporal-order effect even within the same response category, such an effect occurred for novices only between response categories. A second experiment confirmed that these between-group differences are due to domain-specific motor expertise (i.e., high jump) rather than to general motor experiences. Altogether our results suggest that motor expertise results in a more fine-grained posture-based movement representation.     

Feature-based attention to unconscious shapes and colors

Two experiments employed feature-based attention to modulate the impact of completely masked primes on subsequent pointing responses. Participants processed a color cue to select a pair of possible pointing targets out of multiple targets on the basis of their color, and then pointed to the one of those two targets with a prespecified shape. All target pairs were preceded by prime pairs triggering either the correct or the opposite response. The time interval between cue and primes was varied to modulate the time course of feature-based attentional selection. In a second experiment, the roles of color and shape were switched. Pointing trajectories showed large priming effects that were amplified by feature-based attention, indicating that attention modulated the earliest phases of motor output. Priming effects as well as their attentional modulation occurred even though participants remained unable to identify the primes, indicating distinct processes underlying visual awareness, attention, and response control.     

Incidental learning of S-R contingencies in the masked prime task

Subliminal motor priming effects in the masked prime paradigm can only be obtained when primes are part of the task set. In 2 experiments, the authors investigated whether the relevant task set feature needs to be explicitly instructed or could be extracted automatically in an incidental learning paradigm. Primes and targets were symmetrical arrows, with target color, not shape, the response-relevant feature. Shape and color covaried for targets (e.g., <> always blue, >< always green), whereas primes were always black. Over time, a negative compatibility effect (NCE; response benefits when prime and target had different shapes) developed, indicating that primes affected the motor system. When target shape and color varied independently (control condition), no NCE occurred, in line with the assumption that the NCE reflects task set-dependent motor processes, not perceptual interactions.     

Interference and negative priming from ignored distractors: The role of selection difficulty

The relation between distractor interference and negative priming from identical distractors was examined in two experiments. Subjects responded to a target letter, which was indicated by an adjacent bar marker, and attempted to ignore a distracting letter. Onprime trials, distracting letters were either compatible or incompatible with the target, allowing for a measure of interference. On subsequentprobe trials, previously ignored distractors were sometimes presented as targets, allowing for a measure of negative priming. Reducing the spatial separation between targets and distractors on the prime trial increased the magnitude of interferenceand negative priming, but these effects appeared to be independent of each other (Experiment 1). In Experiment 2, the prime target location was precued on some trials, but not on others. Precuing attenuated the magnitude of interference, but not that of negative priming effects. This pattern indicates that measures of negative priming and measures of distractor interference on the immediately preceding trial are independent. The results are discussed in terms of a selective inhibition model of selective attention.     

Facilitatory and inhibitory effects of masked prime stimuli on motor activation and behavioural performance.

Three experiments investigated the impact of information provided by masked stimuli on motor activation. Masked primes were presented prior to target stimuli and these primes were identical to the target on compatible trials, identical to the target mapped to the opposite response on incompatible trials and task-irrelevant on neutral trials. A previous study [Eimer, M., & Schlaghecken, F. (1998). Effects of masked stimuli on motor activation: Behavioural and electrophysiological evidence. Journal of Experimental Psychology: Human Perception and Performance, 24, 1737-1747] found performance costs for compatible trials and benefits for incompatible trials. Experiment 1 showed that these effects are not due to 'perceptual repetition blindness'. Experiments 2 and 3 obtained evidence for an initial response facilitation triggered by the primes that was followed by inhibition. With short intervals between prime presentation and response execution, performance benefits were found for compatible trials and these turned into costs at longer intervals. It is argued that an early response facilitation mediated by direct perceptuo-motor links is subsequently inhibited by a central mechanism operating to prevent behaviour from being controlled by irrelevant information.     

Cognitive inhibition in selection and sequential retrieval

Inhibitory models of working memory efficiency (Engle, 1996; Zacks & Hasher, 1994) assert that individual differences in working memory reflect the efficiency of inhibitory processes that exclude irrelevant information and suppress no-longer-relevant information. The present study examined the implication that these two inhibitory processes operate at consistent levels of efficiency within individuals by examining the correlation between two cognitive inhibition effects, negative priming and negative error priming. Negative priming involves slower response to a probe-trial target that was used as a to-be-ignored distractor on the immediately preceding prime trial. Negative error priming is the phenomenon that errors in a sequence of simple arithmetic trials are unlikely to involve the correct answer to the preceding problem. Participants received distractor-target pairs of simple addition problems and were required to produce the target problem sum. Negative priming was observed for prime distractors, whereas negative error priming was observed in connection with previous targets but not distractors. Consistent with the assumptions of these working memory models, the magnitudes of the two effects were significantly correlated.     

Encoding processes and attentional inhibition in directed forgetting.

Lexical decisions were used to evaluate whether forget (F)-cued prime words affect subsequent encoding of target words relative to remember (R)-cued prime words. In 3 experiments, R-cued primes were better recalled than F-cued primes. Targets that followed F-cued primes were responded to faster than targets that followed R-cued primes in same-case and different-case identity priming. Semantic priming occurred for targets that followed both types of memory-cued primes. However, response times were longer for both related and unrelated targets following R-cued primes relative to F-cued primes. These results indicate that R and F items are processed to similar levels of representation and inhibitory mechanisms do not attenuate encoding of F items. However, there is slower access to working memory for information that follows R-cued items.     

Probing Representations of Gymnastics Movements: A Visual Priming Study

In this study, we designed a visual short‐term priming paradigm to investigate the mechanisms underlying the priming of movements and to probe movement representations in motor experts and matched controls. We employed static visual stimuli that implied or not human whole‐body movements, that is, gymnastics movements and static positions. Twelve elite female gymnasts and twelve matched controls performed a speeded two‐choice response time task. The participants were presented with congruent and incongruent prime‐target pairs and had to decide whether the target stimulus represented a gymnastics movement or a static position. First, a visual priming effect was observed in the two groups. Second, a stimulus–response rote association could not easily account for our results. Novel primes never presented as targets could also prime the targets. Third, by manipulating three levels of prime‐target relations in moving congruent pairs, we demonstrated that the more similar prime‐target pairs, the greater the facilitation in target. Lastly, gymnastics motor expertise impacted on priming effects.     

Inhibition and decay of motor and nonmotor priming

Motor responses can be facilitated by congruent visual stimuli and prolonged by incongruent visual stimuli that are made invisible by masking (direct motor priming). Recent studies on direct motor priming showed a reversal of these priming effects when a three-stimulus paradigm was used in which a prime was followed by a mask and a target stimulus was presented after a delay. A similar three-stimulus paradigm on nonmotor priming, however, showed no reversal of priming effects when the mask was used as a cue for processing of the following target stimulus (cue priming). Experiment 1 showed that the time interval between mask and target is crucial for the reversal of priming. Therefore, the time interval between mask and target was varied in three experiments to see whether cue priming is also subject to inhibition at a certain time interval. Cues indicated (1) the stimulus modality of the target stimulus, (2) the task to be performed on a multidimensional auditory stimulus, or (3) part of the motor response. Whereas direct motor priming showed the reversal of priming about 100 msec after mask presentation, cue priming effects simply decayed during the 300 msec after mask presentation. These findings provide boundary conditions for accounts of inverse priming effects.     

A PRP-study to determine the locus of target priming effects

Visual stimuli that are made invisible by a following mask can nonetheless affect motor responses. To localize the origin of these target priming effects we used the psychological refractory period paradigm. Participants classified tones as high or low, and responded to the position of a visual target that was preceded by a prime. The stimulus onset asynchrony (SOA) between both tasks varied. In Experiment 1 the tone task was followed by the position task and SOA dependent target priming effects were observed. When the visual position task preceded the tone task in Experiment 2, with short SOA the priming effect propagated entirely to the tone task yielding faster responses to tones on visually congruent trials and delayed responses to tones on visually incongruent trials. Together, results suggest that target priming effects arise from processing before and at the level of the central bottleneck such as sensory analysis and response selection.     

Spacing effects in cued-memory tasks for unfamiliar faces and nonwords

Memory for repeated items improves as the interval between repetitions in a list increases (the spacing effect). This study investigated the spacing effect in recognition memory and in a frequency judgment task for unfamiliar target faces that were repeated in the same or in a different pose during incidental learning. Changing the pose between prime and probe trials reduced perceptual repetition priming in a structural discrimination task and also reduced the spacing effect in a subsequent unexpected recognition memory task. Three further experiments confirmed that the spacing effect inrecognition memory (Experiments 2 and 4) or frequency judgment (Experiment 3) was reduced when the pose was changed between repeated presentations at study. Similarly, with nonwords as targets (Experiment 5), changing the font between repeated occurrences of targets at study removed the spacing effect in a subsequent unexpected recognition memory test. These results are interpreted to support the view that short-term perceptual repetition priming underlies the spacing effect in explicit cued-memory tasks for unfamiliar nonsense material.     

How important is a prime's gestalt for subliminal priming?

Masked stimuli (primes) can affect the preparation of a motor response to subsequently presented target stimuli. Under some conditions, reactions to the main stimulus can be facilitated (straight priming) or inhibited (inverse priming) when preceded by a compatible prime (calling for the same response). In the majority of studies in which inverse priming was demonstrated arrows pointing left or right were used as prime and targets. There is, however, evidence that arrows are special overlearned stimuli which are processed in a favorable way. Here we report three experiments designated to test whether the "arrowness" of primes/targets is a sufficient condition for inverse priming. The results clearly show that although inverse priming appeared when non-arrow shapes were used, the magnitude of the priming effect was larger with arrows. The possible reasons for this effect are discussed.