Recently inhibited responses are avoided for both masked and nonmasked primes in a spatial negative priming task

Responding to the location of a target is delayed when the target arises at a position previously occupied by a distractor (ignored-repetition trial), relative to when it occurs at a formerly unoccupied location (control trial) [i.e., the spatial negative priming (SNP) effect]. Speculation has held that recently inhibited (distractor) responses resist future execution (i.e., execution resistance [ER]), and thus cause SNP. Evidence for ER has been reported for identity-based tasks using masked prime distractor events. The purpose of this study was to examine the potential impact of ER on response selection in an SNP task for both nonmasked (traditional) and masked primes. We employed a modified SNP task that included nonmasked and masked target-only and distractor-only visual primes (first trial), along with forced choice and free choice probes (second trial). On free choice trials, a selection bias against the prime-distractor-assigned response was evident (same-hand competition, for both nonmasked and masked primes). This selection avoidance was held to reflect ER operating with inhibited prime distractor responses. Further, inhibitory aftereffect patterns were the same for nonmasked and masked distractor primes, and masking target primes transformed a positive to a negative aftereffect, as predicted by the self-inhibition model of mask function set out by Schlaghecken and Eimer (Psychonomic Bulletin & Review, 11, 463-468, 2004).     

Does subliminal priming of free response choices depend on task set or automatic response activation?

In a task requiring speeded bidirectional responses to arrow symbols (?,?), "free choice" responses to interspersed bidirectional stimuli (<>) are influenced by masked directional primes (e.g., Schlaghecken & Eimer, 2004). By varying stimulus-response (S-R) compatibility, we tested whether this priming effect is mediated by the conscious instructional set, or instead by pre-existing directional associations to the symbols. In two experiments, one group of participants was instructed to respond with the hand consistent with the implied direction of the arrow symbols, while another group was instructed to make the spatially opposite responses. Both groups showed priming of "free choice" responses. However, such priming was always biased according to the instructional set rather than pre-existing associations. Subliminal priming of "free choice" responses therefore depends on conscious task goals.     

数字概念的视知觉无意识语义启动效应

研究了数字概念大小判断任务中的无意识语义启动效应。被试为天津师范大学本科生和研究生 5 6名。仪器为 pentiumIII高分辨率计算机 ,程序用E prime心理实验软件系统编制而成。在实验一中 ,用信号检测论技术发现 ,当启动数字呈现为 30ms时 ,被试是不能觉知到启动数字的 ;在实验二中 ,启动数字和靶数字使用相同的刺激序列 ,用MANOVA分析了启动数字和靶数字属于不同字体时的启动效应 ,发现启动数字对靶数字加工有促进或抑制作用 ;在实验三中 ,启动数字和靶数字使用两个不同的刺激序列 ,同样发现类似的启动效应。实验证据提示 ,无意识知觉能够达到语义水平上的加工     

Masked response priming in expert typists

In masked priming tasks responses are usually faster when prime and target require identical rather than different responses. Previous research has extensively manipulated the nature and number of response-affording stimuli. However, little is known about the constraints of masked priming regarding the nature and number of response alternatives. The present study explored the limits of masked priming in a six-choice reaction time task, where responses from different fingers of both hands were required. We studied participants that were either experts for the type of response (skilled typists) or novices. Masked primes facilitated responding to targets that required the same response, responses with a different finger of the same hand, and with a homologous finger of the other hand. These effects were modulated by expertise. The results show that masked primes facilitate responding especially for experts in the S–R mapping and with increasing similarity of primed and required response.     

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.     

Inhibition from blinked category labels: Combining the attentional blink and the semantic priming paradigm

In the present experiment we combined the attentional blink and the semantic priming paradigm. We used category labels as primes and category exemplars as targets. The prime stimuli were embedded into a rapid serial visual presentation (RSVP) stream and presented at varying positions after a to-be-identified stimulus, albeit the stimulus–onset asynchrony between primes and targets remained constant throughout the experiment. As a result, participants’ prime awareness was reduced in some trials although the prime duration was always at levels usually considered to elicit awareness (60 ms). After each RSVP there was a forced choice discrimination test to assess participants’ prime awareness. When subjects could not identify the prime stimuli we observed slower responses to related as compared to unrelated targets. This result confirms results found with repeated masked primes. However, whereas former studies assessed unawareness rather coarsely at the level of individual participants, here unawareness was tested on a trial-by-trial basis.     

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.     

The Influence of Masked Stimuli on Response Selection: Evidence from a Semantic Categorization Task

Unconscious visual stimuli can be processed by human observers and influence their behaviour. A striking example is a phenomenon known as “free-choice priming,” where masked “prime” stimuli—of which participants are unaware—modulate which of two response alternatives they are likely to choose. Recent efforts to uncover the mechanisms underlying this intriguing effect have revealed that free-choice priming can emerge even in the absence of automatized stimulus-response (S-R) associations between masked primes and specific motor responses, indicating that free choices can be influenced by a masked prime’s meaning (Ocampo, 2015). It remains unknown, however, whether masked primes bias response selections because they are implicitly classified according to task instructions, or because spreading activation occurs within the prime's semantic network. To adjudicate between these two possibilities, participants in the present experiment categorised targets as either animals or people and selected which of two response alternatives they wanted to make following presentation of a free-choice target. Crucially, while implicit classifications could proceed during processing of both animal and person masked primes, only animal primes could trigger spreading activation within their semantic network. This manipulation modulated free-choice priming; only masked animal primes influenced response selections to free-choice targets. This result indicates that an automatic spreading activation mechanism might underlie a masked prime’s ability to influence free-choice responses.     

汉语听觉阈下启动效应：来自听觉掩蔽启动范式的证据

使用汉语双字词为实验材料,采用听觉掩蔽启动范式,通过3个实验考察汉语听觉阈下启动效应。结果发现,真词的听觉阈下重复启动效应显著,并且听觉阈下重复启动效应不受启动、目标发音者性别一致性的影响。但真词的阈下语音、语素和语义启动效应及假词的阈下重复和首字启动效应都不显著。这些结果说明,听觉通道阈下呈现的汉语双字词的词汇水平信息可以得到无意识加工。汉语双字词的听觉阈下启动效应可能是基于启动词整词表征的无意识激活。     

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.     

Masked cross-modal priming turns on a glimpse of the prime

We examined if cross-modal priming (print to speech) was greater for participants who were aware of the presence of letters in the experiment. Experiment 1 determined that word primes displayed at 47 ms were adequately masked. In Experiment 2 (a, b) with primes displayed at 47 ms masked priming occurred for within-mode printed targets but not for spoken ones. Experiment 3, with spoken targets, presented primes at two different durations (59, 71 ms) and priming was found for participants who reported seeing letters but not for those who did not. The results are discussed in terms how the link between prime and target representations might be strengthened even by cursory awareness of the prime and what this tells us about priming.     

Masked priming with orthographic neighbors: a test of the lexical competition assumption

In models of visual word identification that incorporate inhibitory competition among activated lexical units, a word's higher frequency neighbors will be the word's strongest competitors. Preactivation of these neighbors by a prime is predicted to delay the word's identification. Using the masked priming paradigm (K. I. Forster & C. Davis, 1984, J. Segui and J. Grainger (1990) reported that, consistent with this prediction, a higher frequency neighbor prime delayed the responses to a lower frequency target, whereas a lower frequency neighbor prime did not delay the responses to a higher frequency target. In the present experiments, using English stimuli, it was found that this pattern held only when the primes and targets had few neighbors; when the primes and targets had many neighbors, lower frequency primes delayed responses to higher frequency targets essentially as much as higher frequency primes delayed responses to lower frequency targets. Several possible explanations for these findings are discussed along with their theoretical implications. Considered together, the results are most consistent with activation-based accounts of the masked priming effect.     

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.     

On-line control of pointing is modified by unseen visual shapes

Shapes that are rendered invisible through backward masking are still able to influence motor responses: this is called masked priming. Yet it is unknown whether this influence is on the control of ongoing action, or whether it merely influences the initiation of an already-programmed action. We modified a masked priming procedure (Schmidt, 2002) such that the critical prime-mask sequence was displayed during the execution of an already-initiated goal-directed pointing movement. Psychophysical tests of prime visibility indicated that the identity of the prime shapes were not accessible to participants for conscious report. Yet detailed kinematic analysis of the finger in motion revealed that masked primes had an influence on the pointing trajectories within 277ms of their appearance, 56ms earlier than the trajectory deviations observed in response to the visible masks. These results indicate that subliminal shapes can indeed influence the control of ongoing motor activity.     

No evidence for subliminal affective priming with emotional facial expression primes

The present study investigated whether facial expressions of emotion presented outside consciousness awareness will elicit evaluative responses as assessed in affective priming. Participants were asked to evaluate pleasant and unpleasant target words that were preceded by masked or unmasked schematic (Experiment 1) or photographic faces (Experiments 1 and 2) with happy or angry expressions. They were either required to perform the target evaluation only or to perform the target evaluation and to name the emotion expressed by the face prime. Prime-target interval was 300 ms in Experiment 1 and 80 ms in Experiment 2. Naming performance confirmed the effectiveness of the masking procedure. Affective priming was evident after unmasked primes in tasks that required naming of the facial expressions for schematic and photographic faces and after unmasked primes in tasks that did not require naming for photographic faces. No affective priming was found after masked primes. The present study failed to provide evidence for affective priming with masked face primes, however, it indicates that voluntary attention to the primes enhances affective priming.     

The influence of intention on masked priming: a study with semantic classification of words

Unconscious perception is commonly described as a phenomenon that is not under intentional control and relies on automatic processes. We challenge this view by arguing that some automatic processes may indeed be under intentional control, which is implemented in task-sets that define how the task is to be performed. In consequence, those prime attributes that are relevant to the task will be most effective. To investigate this hypothesis, we used a paradigm which has been shown to yield reliable short-lived priming in tasks based on semantic classification of words. This type of study uses fast, well practised classification responses, whereby responses to targets are much less accurate if prime and target belong to a different category than if they belong to the same category. In three experiments, we investigated whether the intention to classify the same words with respect to different semantic categories had a differential effect on priming. The results suggest that this was indeed the case: Priming varied with the task in all experiments. However, although participants reported not seeing the primes, they were able to classify the primes better than chance using the classification task they had used before with the targets. When a lexical task was used for discrimination in experiment 4, masked primes could however not be discriminated. Also, priming was as pronounced when the primes were visible as when they were invisible. The pattern of results suggests that participants had intentional control on prime processing, even if they reported not seeing the primes.     

Being forward not backward: lexical limits to masked priming

This study investigated whether masked priming is mediated by existing memory representations by determining whether nonwords targets would show repetition priming. To avoid the potential confound that nonword repetition priming would be obscured by a familiarity response bias, the standard lexical decision and naming tasks were modified to make targets unfamiliar. Participants were required to read a target string from right to left (i.e., "ECAF" should be read as "FACE") and then make a response. To examine if priming was based on lexical representations, repetition primes consisted of words when read forwards or backwards (e.g., "face", "ecaf") and nonwords (e.g., "pame", "emap"). Forward and backward primes were used to test if task instruction affected prime encoding. The lexical decision and naming tasks showed the same pattern of results: priming only occurred for forward primes with word targets (e.g., "face-ECAF"). Additional experiments to test if response priming affected the LDT indicated that the lexical status of the prime per se did not affect target responses. These results showed that the encoding of masked primes was unaffected by the novel task instruction and support the view that masked priming is due to the automatic triggering of pre-established computational processes based on stored information.     

Effects of prime-target spatial separation and attentional deployment on masked repetition priming

In two masked repetition priming experiments with letter stimuli, the positions of prime and target stimuli were varied horizontally from fixation. Priming effects did not interact with position when prime and target location covaried (Experiment 1A) but diminished with increasing prime eccentricity when targets were always centrally located (Experiment 1B). Two accounts of this pattern of priming effects were proposed that postulate two different mechanisms over and above effects of visual acuity. The integration account postulates degree of separation of prime and target stimuli as the critical factor, and the attentional account postulates spatial attention as the critical factor. The results of Experiment 2, in which prime and target positions were manipulated orthogonally, were in favor of the attentional account. Repetition priming did not vary as a function of whether or not primes and targets appeared at the same location, but target processing was facilitated independently of priming when targets appeared at the same location as primes, especially in the right visual field.     

负相容效应理论与研究

负相容效应指在掩蔽的箭头启动项后呈现箭头目标项时,对与启动项方向不一致的目标项反应更快。综述了负相容效应的主要理论及研究,包括自我抑制理论和知觉交互作用理论等。讨论了目前负相容效应研究面临的困难与挑战,包括实验控制条件的限制、掩蔽项与启动项特征的相似性以及应用认知神经研究方法进行研究的困难,并从理论更新与整合、神经基础、生态学意义视角等几方面对未来的研究做出展望。     

Mechanisms of Priming by Masked Stimuli: Inferences From Event-Related Brain Potentials

A metacontrast procedure was combined with the recording of event-related potentials (ERPs) to examine the mechanisms underlying the priming effect exerted by masked visual stimuli (primes) on target processing. Participants performed spatially arranged choice responses to stimulus locations. The relationship between prime and target locations (congruity) and the mapping between target and response locations (compatibility) were factorially manipulated. Although participants were unaware of prime locations, choice responses were faster for congruent than incongruent conditions irrespective of the mapping. Visual ERP components and the onset of the lateralized readiness potential (LRP), an index of specific motor activation, revealed that neither perceptual nor preselection processes contributed to the congruity effect. However, the LRP waveform indicated that primes activated responses that fit the stimulus-response mapping. These results support the view that sensorimotor processing of masked stimuli is functionally distinct from their conscious perception.