Controlling the unconscious: attentional task sets modulate subliminal semantic and visuomotor processes differentially

Are unconscious processes susceptible to attentional influences? In two subliminal priming experiments, we investigated whether task sets differentially modulate the sensitivity of unconscious processing pathways. We developed a novel procedure for masked semantic priming of words (Experiment 1) and masked visuomotor priming of geometrical shapes (Experiment 2). Before presentation of the masked prime, participants performed an induction task in which they attended to either semantic or perceptual object features designed to activate a semantic or perceptual task set, respectively. Behavioral and electrophysiological effects showed that the induction tasks differentially modulated subliminal priming: Semantic priming, which involves access to conceptual meaning, was found after the semantic induction task but not after the perceptual induction task. Visuomotor priming was observed after the perceptual induction task but not after the semantic induction task. These results demonstrate that unconscious cognition is influenced by attentional control. Unconscious processes in perceptual and semantic processing streams are coordinated congruently with higher-level action goals.     

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。     

Parts outweigh the whole (word) in unconscious analysis of meaning

In unconscious semantic priming, an unidentifiable visually masked word (the prime) facilitates semantic classification of a following visible related word (the target). Three experiments reported here provide evidence that masked primes are analyzed mainly at the level of word parts, not whole-word meaning. In Experiment 1, masked nonword primes composed of subword fragments of earlier-viewed targets functioned as effective evaluative primes. (For example, after repeated classification of the targets angel and warm , the nonword anrm acted as an evaluatively positive masked prime.) Experiment 2 showed that this part-word processing was potent enough to oppose analysis at the whole-word level. Thus, smile functioned as an evaluatively negative (!) masked prime after repeated classification of smut and bile . Experiment 3 found no priming when masked word primes contained no parts of earlier targets. These results suggest that robust unconscious priming (a) is driven by analysis of part-word information and (b) requires previous classification of visible targets that contain the fragments later serving as primes. Contrary to a widely held view, analysis of subliminal primes appears not to function at the level of analysis of complete words.     

序列语义的类别一致性关系能否进行无意识整合？

阈下语义之间能否进行整合,最近的研究给出了不同的结果。当多个阈下语义词语同时呈现时显示出无意识语义整合效应,但是当序列呈现时没有观察到无意识整合效应。本研究在保留同时呈现方法优点（不同空间呈现位置）的情况下研究了序列呈现的不同汉字词语之间能否产生无意识语义类别关系整合。在实验1中,两个相同或不同类别的词语作为阈下启动刺激先后在两侧呈现,且第一个词语消失后第二词语马上出现,结果显示出无意识语义类别整合效应。实验2延长了两个阈下启动词语之间的时间间隔,结果未发现无意识语义类别整合效应。另外,实验3进一步排除了实验1中第一个启动词语的视觉残留,结果也未观察到显著的无意识语义类别整合效应,说明实验1中观察到的无意识整合效应是视觉残留所致。综合三个实验结果表明,两个阈下词语之间的语义类别一致性关系只有在同时呈现这种特殊条件下才能进行无意识整合加工,说明了短时间维度对于无意识语义关系整合的重要性。     

序列语义的类别一致性关系能否进行无意识整合？

阈下语义之间能否进行整合,最近的研究给出了不同的结果。当多个阈下语义词语同时呈现时显示出无意识语义整合效应,但是当序列呈现时没有观察到无意识整合效应。本研究在保留同时呈现方法优点（不同空间呈现位置）的情况下研究了序列呈现的不同汉字词语之间能否产生无意识语义类别关系整合。在实验1中,两个相同或不同类别的词语作为阈下启动刺激先后在两侧呈现,且第一个词语消失后第二词语马上出现,结果显示出无意识语义类别整合效应。实验2延长了两个阈下启动词语之间的时间间隔,结果未发现无意识语义类别整合效应。另外,实验3进一步排除了实验1中第一个启动词语的视觉残留,结果也未观察到显著的无意识语义类别整合效应,说明实验1中观察到的无意识整合效应是视觉残留所致。综合三个实验结果表明,两个阈下词语之间的语义类别一致性关系只有在同时呈现这种特殊条件下才能进行无意识整合加工,说明了短时间维度对于无意识语义关系整合的重要性。     

负相容效应中启动项-目标项关系对阈下信息加工的影响

采用掩蔽启动范式考察了负相容效应中启动项与目标项关系对阈下信息加工的影响,以及是否存在语义水平的负相容效应.两个实验分别以双箭头和汉字为掩蔽启动项,考察启动项和目标项重复、加工水平相同及加工水平不同三种条件下的启动效应.结果发现,两个实验的重复及加工水平相同条件下都出现负相容效应,且重复条件下启动量最大,加工水平不同条件下则无启动.这表明:(1)启动项与目标项的知觉重复影响启动量,但不是负相容效应的必要条件,只有当启动项和目标项加工水平相同时,才出现负相容效应;(2)存在语义水平上的负相容效应,阈下语义信息可得到加工并表现为对后继同类反应的抑制.     

具身认知视角下语义理解中的身体角色:以研究方法为线索

具身认知认为,概念形成和语言理解等高级心理过程本质上是以感知觉和运动经验为基础的。神经影像学研究发现,理解身体动作词激活了支配该部分肢体的感觉运动脑区。理解手部、脚部和面部动作词能够相应激活支配手部、脚部和面部的感觉运动脑区,体现出一种身体动作词语义理解激活的脑区与真实身体动作激活脑区的耦合效应。临床和经颅磁刺激研究结果表明,感觉运动皮层的激活与身体动作词语义处理具有因果性作用。未来研究应关注身体动作词语义理解的具身程度以及相关语言疗法在临床患者机能恢复中所起的作用。     

Unconscious processing of multiple nonadjacent letters in visually masked words

The claim that visually masked, unidentifiable ("subliminal") words are analyzed at the level of whole word meaning has been challenged by recent findings indicating that instead, analysis occurs mainly at the subword level. The present experiments examined possible limits on subword analysis. Experiment 1 obtained semantic priming from pleasant- and unpleasant-meaning subliminal words in which no individual letter contained diagnostic information about a word's evaluative valence; thus analysis must operate on information more complex than that contained in individual letters. Experiments 2 and 3 showed that analysis must operate on information more complex than that represented by individual bigrams (adjacent letters) or trigrams (three consecutive letters). These findings suggest that while subliminal priming is driven by subword analysis, the effective units of analysis are distributed widely across at least short (four- and five-letter) words.     

Unconscious processing of dichoptically masked words

In three experiments, the subjects' task was to decide whether each of a series of words connoted something good (e.g., fame, comedy, rescue) or bad (stress, detest, malaria). One-half second before the presentation of each such target word, an evaluatively polarized priming word was presented briefly to the nondominant eye and was masked dichoptically by either the rapidly following (Experiment 1) or simultaneous (Experiments 2 and 3) presentation of a random letter-fragment pattern to the dominant eye. (The effectiveness of the masking procedure was demonstrated by the subjects' inability to discriminate the left vs. right position of a test series of words.) In all experiments, significant masked priming effects were obtained; evaluative decisions to congruent masked prime-target combinations (such as a positive masked prime followed by a positive target) were significantly faster than those to incongruent (e.g., negative prime/positive target) or noncongruent (e.g., neutral prime/positive target) combinations. Also, in two of the three experiments, when subjects were at chance accuracy in discriminating word position, their position judgments were nevertheless significantly influenced by the irrelevant semantic content (LEFT vs. RIGHT) of the masked position-varying words. The series of experiments demonstrated that two very different tasks--speeded judgment of evaluative meaning and nonspeeded judgment of word position--yielded statistically significant and replicable influences of the semantic content of apparently undetectable words. Coupled with previous research by others using the lexical decision task, these findings converge in establishing the reliability of the empirical phenomenon of semantic processing of words that are rendered undetectable by dichoptic pattern masking.     

Role of consciousness in temporal integration of semantic information

Previous studies found that word meaning can be processed unconsciously. Yet it remains unknown whether temporally segregated words can be integrated into a holistic meaningful phrase without consciousness. The first four experiments were designed to examine this by sequentially presenting the first three words of Chinese four-word idioms as prime to one eye and dynamic Mondrians to the other (i.e., the continuous flash suppression paradigm; CFS). An unmasked target word followed the three masked words in a lexical decision task. Results from such invisible (CFS) condition were compared with the visible condition where the preceding words were superimposed on the Mondrians and presented to both eyes. Lower performance in behavioral experiments and larger N400 event-related potentials (ERP) component for incongruent- than congruent-ending words were found in the visible condition. However, no such congruency effect was found in the invisible condition, even with enhanced statistical power and top-down attention, and with several potential confounding factors (contrast-dependent processing, long interval, no conscious training) excluded. Experiment 5 demonstrated that familiarity of word orientation without temporal integration can be processed unconsciously, excluding the possibility of general insensitivity of our paradigm. The overall result pattern therefore suggests that consciousness plays an important role in semantic temporal integration in the conditions we tested.     

语言和情境对具体概念感知运动仿真的影响

具体概念加工中的感知运动仿真是概念表征的核心加工过程。本研究系统探讨了语言因素(语言类型：第一语言和第二语言)和情境因素(知觉情境：空间知觉情境和语义知觉情境)对具体概念加工中感知运动仿真的影响。实验1采用语义相关判断范式探讨了第二语言加工过程中是否存在感知运动仿真, 以及第二语言中的仿真和第一语言中的仿真是否存在差异。研究发现, 第二语言加工中依然存在感知运动仿真, 但是第一语言的感知运动仿真具有一定的优势。实验2采用语义相关判断范式及其变式, 通过2个分实验分别探讨了个体加工概念时空间知觉信息和语义知觉信息对于概念表征过程中感知运动仿真的影响。研究发现, 无论是在较弱的空间信息知觉条件下还是在较浅的语义信息知觉条件下, 具体概念加工过程中都产生了感知运动仿真。本研究的发现弥补了知觉符号理论未对第二语言中的感知运动仿真提出针对性预测的不足, 表明感知运动仿真具有一定的跨语言稳定性。同时, 具体概念加工中的感知运动仿真不受空间信息和语义信息的调节, 这表明感知运动仿真能在一定程度上自动化产生。     

Opposite ERP effects for conscious and unconscious semantic processing under continuous flash suppression

We examined whether semantic processing occurs without awareness using continuous flash suppression (CFS). In two priming tasks, participants were required to judge whether a target was a word or a non-word, and to report whether the masked prime was visible. Experiment 1 manipulated the lexical congruency between the prime-target pairs and Experiment 2 manipulated their semantic relatedness. Despite the absence of behavioral priming effects (Experiment 1), the ERP results revealed that an N4 component was sensitive to the prime-target lexical congruency (Experiment 1) and semantic relatedness (Experiment 2) when the prime was rendered invisible under CFS. However, these results were reversed with respect to those that emerged when the stimuli were perceived consciously. Our findings suggest that some form of lexical and semantic processing can occur during CFS-induced unawareness, but are associated with different electrophysiological outcomes.     

Partial awareness creates the "illusion" of subliminal semantic priming

We argue that the lack of consensus regarding the existence of subliminal semantic processing arises from not taking into account the fact that linguistic stimuli are represented across several processing levels (features, letters, word form) that can independently reach or not reach awareness. Using masked words, we constructed conditions in which participants were aware of some letters or fragments of a word, while remaining unaware of the whole word. Three experiments using the Stroop priming paradigm show that when the stimulus set is reduced and participants are encouraged to guess the identity of the prime, such partially perceived stimuli can nonetheless give rise to "semantic" processing. We provide evidence that this effect is due to illusory reconstruction of the incompletely perceived stimulus, followed by usual semantic processing of the result. We conclude that previously reported unconscious Stroop priming is in fact a conscious effect, but applied to a perceptual illusion.     

Number-of-features effects and semantic processing

Participants list many semantic features for some concrete nouns (e.g., lion) and fewer for others (e.g., lime; McRae, de Sa, & Seidenberg, 1997). Pexman, Lupker, and Hino (2002) reported faster lexical decision and naming responses for high number of features (NOF) words than for low-NOF words. In the present research, we investigated the impact of NOF on semantic processing. We observed NOF effects in a self-paced reading task when prior context was not congruent with the target word (Experiment 1) and in a semantic categorization task (concrete vs. abstract; Experiment 2A). When we narrowed our stimuli to include high- and low-NOF words from a single category (birds), we found substantial NOF effects that were modulated by the specificity of the categorization task (Experiments 3A, 3B, and 3C). We argue that these results provide support for distributed representation of word meaning.     

熟练中-英双语者对多义词早期识别中语义和语法的相互作用

以中、英文的多义词为材料, 采用跨语言隐蔽启动的实验范式, 考察在无语境条件下熟练中–英双语者对多义词的早期识别。结果表明：(1)熟练中–英双语者表现出显著的隐蔽翻译启动效应, 当目标词是主要翻译对等词时, 启动效应更加显著。(2)翻译对等词的性质、多义词的义项联系程度以及是否是词类歧义词都影响熟练中–英双语者对中、英多义词的早期加工。(3)在无语境条件下, 词类信息在意义通达的早期就已经激活, 并且同语义信息之间存在着交互作用。根据研究结果, 扩展和修正了分布式概念表征模型。     

Retroactive semantic priming in a lexical decision task

The present study reports two experiments that required subjects to name target items preceded by a masked prime. Additionally, and subsequent to the naming task, subjects were required to indicate whether or not the prime was a word, along with a confidence rating of their lexical decision. Experiment 1 demonstrates that the processing of masked primes is facilitated by related targets when such targets are presented either 100 or 200 msec after the onset of the prime. Experiment 2 extends the finding of “retroactive” priming to a 1000=msec separation in prime-target presentation (SOA). The extent of retroactive priming is not dependent on SOA between prime and target, nor is it affected by the prime-mask SOA, which varied from 10 to 180 msec. Priming of targets was also independent of prime-target and prime-mask SOA, providing that primes had been classified as words. For word primes classified as non-words there was no semantic priming on target naming reaction time. Implications of these findings with respect to the nature of retroactive priming and the current controversy concerning subliminal priming effects were discussed.     

Unconscious semantic priming extends to novel unseen stimuli

Many subliminal priming experiments are thought to demonstrate unconscious access to semantics. However, most of them can be reinterpreted in a non-semantic framework that supposes only that subjects learn to map non-semantic visual features of the subliminal stimuli onto motor responses. In order to clarify this issue, we engaged subjects in a number comparison task in which the target number was preceded by another invisible masked number. We show that unconscious semantic priming occurs even for prime stimuli that are never presented as target stimuli, and for which no stimulus–response learning could conceivably occur. We also report analyses of the impact of the numerical relation between prime and target, and of the impact of learning on priming, all of which confirm that unconscious utilization of semantic information is indeed possible.     

Subliminal words activate semantic categories (not automated motor responses)

Semantic priming by visually masked, unidentifiable (“subliminal”) words occurs robustly when the words appearing as masked primes have been classified earlier in practice as visible targets. It has been argued (Damian, 2001) that practice enables robust subliminal priming by automatizing learned associations between words and the specific motor responses used to classify them. Two experiments demonstrate that, instead, the associations formed in practice that underlie subliminal priming are between words and semantic categories. Visible words classified aspleasant or unpleasant in practice with one set of response key assignments functioned later as subliminal primes with appropriate valence, even when associations of keys with valences were reversed before the test. This result shows that subliminal priming involves unconscious categorization of the prime, rather than just the automatic activation of a practiced stimulus-response mapping.