Anticipatory attention during the sleep onset period

To examine whether anticipatory attention or expectancy is a cognitive process that is automatic or requires conscious control, we employed a paired-stimulus event-related potential (ERP) paradigm during the transition to sleep. The slow negative ERP wave observed between two successive stimuli, the Contingent Negative Variation (CNV), reflects attention and expectancy to the second stimulus. Thirteen good sleepers were instructed to respond to the second stimulus in a pair during waking sessions. In a non-response paradigm modified for sleep, participants then fell asleep while tones played. As expected, N1 decreased and P2 increased in amplitude systematically with the loss of consciousness at sleep onset; the CNV was increasingly more positive. Sleep onset latency was correlated with the amplitude of the CNV. The systematic attenuation of the CNV waveform at sleep onset and its absence in sleep indicates that anticipatory attention requires endogenous conscious control.     

Comparing the effects of conscious monitoring and conscious control on motor performance

We compared the effects of conscious monitoring and control on motor performance. Participants were instructed to adopt an internal or external focus of attention in different blocks of a darts task. For one group, the internal as well as external focus instructions emphasized monitoring. For another group, the instructions emphasized control in the two focus conditions. Furthermore, participants’ propensity for monitoring and control was gauged via two factors of the Movement Specific Reinvestment Scale (MSRS) (Masters, Eves, & Maxwell, 2005). These factors were Movement Self-Consciousness (MS-C) and Conscious Motor Processing (CMP), which measure propensity for conscious monitoring and control, respectively. Performance differences between the internal and external focus blocks were expressed as mean radial error (MRE). Results revealed a 3-way interaction between CMP, instruction type (monitoring versus control) and an order effect. Only in the conscious control-group, but not the conscious monitoring-group was there a 2-way interaction between CMP and order. In the conscious control-group, participants with high CMP scores showed worse performance in whichever focus block (internal or external) was presented last. There were no significant effects in the monitoring-group or of MS-C. These findings indicate that conscious control has a stronger effect on motor performance than conscious monitoring.     

Top-down versus bottom-up: when instructions overcome automatic retrieval

Research on human action has extensively covered controlled and automatic processes in the transformation of stimulus information into motor action, and how conflict between both types of processes is solved. However, the question of how automatic stimulus–response (S–R) translation per se depends on top-down control states remains unanswered. The present study addressed this issue by manipulating top-down control state (instructed S–R mapping) and automatic bottom-up processing (retrieval of S–R memory traces) independently from each other. Using a color/shape task-switching paradigm, we compared cross-talk triggered by distractor stimuli, for which the instructed S–R mapping and the S–R associations compiled at the beginning of the experiment matched, with the cross-talk triggered by distractor stimuli, for which (re-)instructed mapping and compiled S–R associations did not match. We show that the latter distractors do not yield any cross-talk in RTs and even reversed cross-talk in error rates, demonstrating that automatic S–R retrieval is modulated by top-down control states.     

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.     

错误记忆的产生是否依赖对词表的有意加工：无意识激活的证据

使用DRM范式考察了错误记忆产生过程中无意识激活的存在与否。通过操纵实验任务和呈现方式,导致被试对学习词表的无意加工和不同水平的有意加工。结果发现,无意加工时所产生的对关键诱饵的无意识激活足以导致错误记忆效应,说明对词表的有意加工并非错误记忆产生所必需。随着对词表有意加工水平的提高,多次无意识激活的累积可导致增强的错误记忆效应,且表现出与真实记忆的共变,而阻断连续激活累积的因素可有效降低错误记忆     

Gender differences in implicit and explicit processing of emotional facial expressions as revealed by event-related theta synchronization

Emotion information processing may occur in 2 modes that are differently represented in conscious awareness. Fast online processing involves coarse-grained analysis of salient features and is not represented in conscious awareness; offline processing takes hundreds of milliseconds to generate fine-grained analysis and is represented in conscious awareness. These processing modes may be studied using event-related electroencephalogram theta synchronization as a marker of emotion processing. Two experiments were conducted that differed on the mode of emotional information presentation. In the explicit mode, subjects were explicitly instructed to evaluate the emotional content of presented stimuli; in the implicit mode, their attention was directed to other features of the stimulus. In the implicit mode, theta synchronization was most pronounced in the early processing stage, whereas in the explicit mode, it was more pronounced in the late processing stage. The early processing stage was more pronounced in men, whereas the late processing stage was more pronounced in women. Implications of these gender differences in emotion processing for well-documented differences in social behavior are discussed.     

A forced-attention dichotic listening fMRI study on 113 subjects

We report fMRI and behavioral data from 113 subjects on attention and cognitive control using a variant of the classic dichotic listening paradigm with pairwise presentations of consonant-vowel syllables. The syllable stimuli were presented in a block-design while subjects were in the MR scanner. The subjects were instructed to pay attention to and report either the left or right ear stimulus. The hypothesis was that paying attention to the left ear stimulus (FL condition) induces a cognitive conflict, requiring cognitive control processes, not seen when paying attention to the right ear stimulus (FR condition), due to the perceptual salience of the right ear stimulus in a dichotic situation. The FL condition resulted in distinct activations in the left inferior prefrontal gyrus and caudate nucleus, while the right inferior frontal gyrus and caudate were activated in both the FL and FR conditions, and in a non-instructed (NF) baseline condition.     

Conscious contents as reflexive processes: Evidence from the habituation of high-level cognitions

Reflexes are often insuppressible, predictable, and susceptible to external control. In contrast, conscious thoughts have been regarded as whimsical, ‘offline,’ and shielded from external control. Recent advances suggest that conscious thoughts are more reflex-like and susceptible to external control than previously thought. In one paradigm, high-level conscious thoughts (subvocalizations) are triggered by external control, as a function of external stimuli and experimenter-induced action sets. It has been hypothesized that these conscious contents are activated involuntarily and in a reflex-like manner. If such is the case, then these activations should possess a well-known property of the reflex: habituation. Accordingly, we found that involuntary high-level cognitions (subvocalizations) habituated (i.e., were less likely to arise) after repeated stimulation. As in the case of the habituation of a reflex, this novel effect was stimulus-specific. We discuss the implications of this finding for theories about consciousness and about psychopathological phenomena involving undesired, involuntary cognitions.     

Information processing during sleep onset and sleep.

This Special Section examines the extent of information processing during sleep onset and sleep itself. It is generally agreed that, stimulus input is markedly inhibited during sleep, thus preventing conscious awareness of the external environment. Overt behavioural responses are rarely made within sleep. Two neurophysiological measures are therefore often used. The electrical activity of the brain (the EEG) can be employed to distinguish waking (conscious) from sleeping (unconscious) states. It is also possible to quantify the EEG prior to and following a detection (or a failure of a detection) of a stimulus. Such measures can thus be used to predict conscious awareness. A second measure that frequently has been employed is the brain's response to an external stimulus (the evoked potential). Different components of the evoked potential can be used to trace the extent of information processing during the different states of consciousness. Some are associated with a preconscious detection while others are associated with conscious awareness. Other evoked potentials may be unique to sleep.     

Social inference and individual differences in aggression: Evidence for spontaneous judgments of hostility

This research examined the hypothesis that aggressive vs. nonaggressive individuals differ in their spontaneous trait inferences, i. e., inferences made without any conscious intention of inferring characteristics of an actor. We anticipated that spontaneous processing conditions would be more revealing of aggressive/nonaggressive differences than would conditions that prompt deliberate inference processes. We used a cued-recall paradigm. Aggressive and nonaggressive subjects were instructed to memorize sentences that were open to either hostile or nonhostile interpretations. Sentence recall was then cued by either hostile dispositional terms or by words that were linked semantically to the element of the sentences. Within the spontaneous inference condition, semantic cues prompted twice as much recall as hostile cues among nonaggressive subjects, whereas dispositional cues aided recall more than semantic cues among aggressive subjects. As predicted, within the delinerate inference conditions there were no aggressive/nonaggressive differences. The nature of spontaneous vs. deliberate inferential processes and the advantages of spontaneous inference paradigms for testing predictions about schema-based processing in aggression are discussed. © 1995 Wiley-Liss, Inc.     

Noise exclusion in spatial attention

Precue validity affects the performance of perceptual tasks. These spatial attention effects have been variously attributed to facilitation of processing, capacity allocation, or noise reduction. We used a new attention-plus-external (stimulus)-noise paradigm and model to identify the mechanisms of attention in cue-validity paradigms. A new phenomenon is reported: a large effect of location cue validity in an orientation identification task that specifically occurs when the stimulus is embedded in external (environmental or stimulus) noise. This result identifies the mechanism of the effect as external-noise exclusion, distinguished from stimulus enhancement that manifests itself only in noiseless stimulus environments.     

Implicit versus explicit learning processes in a probabilistic, continuous fine-motor catching task

We compared the influences of explicit instruction and uninstructed implicit learning of correlations among visual events, in a fine-motor task. The task required visual tracking of a small "ball" of light and "catching" it by means of joystick manipulation. A general pattern of improvement with practice for instructed and "noninstructed" conditions was found. Additionally, both instructed and noninstructed conditions evidenced use of the predictive relationships among stimulus events. The improvement in overall performance caused by explicit verbal instructions was less than the improvement seen with the implicit learning condition. Further, instructed and noninstructed conditions showed different patterns of joystick activity. These findings suggest a qualitatively different approach to visual information processing and task performance for the instructional conditions     

Parallel perceptual processing and decisional strategies: A reinterpretation of the Shaw and LaBerge effect

A reinterpretation is offered for an effect found by Shaw and LaBerge (1971) in a tachistoscopic detection paradigm. Their Ss were instructed to “scan” the letters of a multiletter stimulus array in a particular sequence. The Ss were more accurate in identifying a target letter if it occurred earlier rather than later in the instructed sequence. Although Shaw and LaBerge interpreted this result as supporting a limited-capacity attentional mechanism, the result is also consistent with a nonattentional parallel processing conception: the payoff incentives used to encourage the correct “scanning sequence” could alter Ss’ postperceptual decisional strategy so as to produce the results obtained. Given the compatibility of a parallel processing conception with the results of Shaw and LaBerge and the results of other detection experiments, the need for postulating a spatial capacity limit or attentional mechanism is questioned.     

Does an instruction to forget enhance memory for other presented items?

In an item-method directed forgetting paradigm, participants were required to attend to one of two colored words presented on opposite sides of a central fixation stimulus; they were instructed to Remember or Forget the attended item. On a subsequent recognition test, the Attended words showed a typical directed forgetting effect with better recognition of Remember words than Forget words. Our interest was in the fate of the Unattended words. When the study display disappeared before the memory instruction, there was no effect of that instruction on unattended words; when the study display remained visible during presentation of the memory instruction, there was a reverse directed forgetting effect with better recognition of unattended words from Forget trials than from Remember trials. Incidental encoding of task-irrelevant stimuli occurs following presentation of a Forget instruction - but only when those task-irrelevant stimuli are still visible in the external environment.     

Context-dependent brightness priming occurs without visual awareness

Our visual systems account for stimulus context in brightness perception, but whether such adjustments occur for stimuli that we are unaware of has not been established. We therefore assessed whether stimulus context influences brightness processing by measuring unconscious priming with metacontrast masking. When a middle-gray disk was presented on a darker (or brighter) background, such that it could be consciously perceived as brighter (or darker) via simultaneous brightness contrast (SBC), reaction times were significantly faster to a bright (or dark) annulus than to a dark (or bright) annulus. We further show that context-dependent brightness priming does not correlate with visibility using an objective measure of awareness (Experiment 1) and that context-dependent, but not context-independent brightness priming, occurs equally strongly for stimuli below or above the subjective threshold for awareness (Experiment 2). These results suggest that SBC occurs at early levels of visual input and is not influenced by conscious perception.     

The relation between consciousness and attention: An empirical study using the priming paradigm

Dehaene et al., 2006, Koch and Tsuchiya, 2007 recently proposed taxonomies that distinguish between four processing states, based on bottom-up stimulus strength and top-down attentional amplification. The aim of the present study was to empirically test these processing states using the priming paradigm. Our results showed that attention (prime attended or not) and stimulus strength (prime presented subliminally or not) significantly modulated priming effects: either receiving top-down attention or possessing sufficient bottom-up strength was a prerequisite for a stimulus to elicit priming. When both top-down attention and sufficient bottom-up strength were present, the priming effect was boosted. The origins of the observed priming effects also varied between different processing states. We can conclude that our empirical study using the priming paradigm confirmed the presence of four processing states, which displayed a differential pattern of response priming effects and differential origins of the response priming effects.     

颜色字词的识别真的无需注意力资源的参与?——来自Stroop范式的证据

3个实验采用颜色词、颜色词同音词以及颜色语义联想词作为启动词,使启动词的语义和颜色实现时空分离、启动词处于非空间注意焦点位置、降低启动词可视度的情境下,考察具有自动化加工特征的启动词是否受到注意力资源的制约以及启动词在获得不同数量的注意力资源时其自动化程度是否存在显著的差异。结果发现:(1)注意力资源实质性地决定着自动化加工能否顺利进行,具有自动激活特征的刺激在无法获得注意力资源时,自动化加工过程终止。(2)可用的注意力资源数量调控着自动化加工的效率和语义提取的效果,可用的注意力资源数量越多,对启动刺激的语义加工越完善,对目标刺激的促进效果也越有效。本研究结果支持注意力敏感模型关于自动化加工受认知系统的支持和配置才能完成的假设。     

Orientation-selective adaptation to crowded illusory lines

Visual adaptation has been successfully used as a psychophysical tool for studying the functional organisation of visual awareness. It has been shown that orientation-selective adaptation to a grating pattern occurs in crowded conditions. In such conditions, simultaneous presentation of flanking distractors pushes the target stimulus out of conscious perception and severely impairs orientation discrimination in the periphery of the visual field. In the present study, orientation-selective adaptation to illusory lines induced by two line gratings abutting each other with a phase shift was examined in crowded and non-crowded conditions. To rule out the effects of lower level adaptations we used an animation paradigm in which the orientations of the two line gratings were altered repeatedly during adaptation phase without any change in the orientation of the resulting illusory line. Although performance of subjects in reporting the orientation of crowded illusory lines was at chance level, orientation-selective adaptation was preserved for crowded as well as non-crowded adapting targets. Two control experiments demonstrated that adaptation to endpoints of real lines at the location of abutting grating lines had minimal effect on the adaptation to illusory lines; and changes in the configuration of endpoints could not be responsible for better performance when adapting and test stimuli were different. We conclude that a crowding effect occurs after illusory lines have been processed in the visual stream. Since illusory lines seem to be represented at relatively early stages of visual processing (e.g. area V2), adaptation to crowded illusory stimuli suggests that neuronal activation in those early stages is not necessarily correlated with conscious perception.     

Evidence for a response preparation bottleneck during dual-task performance: Effect of a startling acoustic stimulus on the psychological refractory period

The present study was designed to investigate the mechanism associated with dual-task interference in a psychological refractory period (PRP) paradigm. We used a simple reaction time paradigm consisting of a vocal response (R1) and key-lift task (R2) with a stimulus onset asynchrony (SOA) between 100 ms and 1500 ms. On selected trials we implemented a startling acoustic stimulus concurrent with the second stimulus to determine if we could involuntarily trigger the second response. Our results indicated that the PRP delay in the second response was present for both control and startle trials at short SOAs, suggesting the second response was not prepared in advance. These results support a response preparation bottleneck and can be explained via a neural activation model of preparation. In addition, we found that the reflexive startle activation was reduced in the dual-task condition for all SOAs, a result we attribute to prepulse inhibition associated with dual-task processing.     

Dynamic visuomotor synchronization: Quantification of predictive timing

When a moving target is tracked visually, spatial and temporal predictions are used to circumvent the neural delay required for the visuomotor processing. In particular, the internally generated predictions must be synchronized with the external stimulus during continuous tracking. We examined the utility of a circular visual-tracking paradigm for assessment of predictive timing, using normal human subjects. Disruptions of gaze–target synchronization were associated with anticipatory saccades that caused the gaze to be temporarily ahead of the target along the circular trajectory. These anticipatory saccades indicated preserved spatial prediction but suggested impaired predictive timing. We quantified gaze–target synchronization with several indices, whose distributions across subjects were such that instances of extremely poor performance were identifiable outside the margin of error determined by test–retest measures. Because predictive timing is an important element of attention functioning, the visual-tracking paradigm and dynamic synchronization indices described here may be useful for attention assessment.