Hemispheric asymmetries in semantic processing: evidence from false memories for ambiguous words

We used fMRI to investigate competition during language production in two word production tasks: object naming and color naming of achromatic line drawings. Generally, fMRI activation was higher for color naming. The line drawings were followed by a word (the distractor word) that referred to either the object, a related object, or an unrelated object. The effect of the distractor word on the BOLD response was qualitatively different for the two tasks. The activation pattern suggests two different kinds of competition during lexical retrieval: (1) Task-relevant responses (e.g., red in color naming) compete with task-irrelevant responses (i.e., the object’s name). This competition effect was dominant in prefrontal cortex. (2) Multiple task-relevant responses (i.e., target word and distractor word) compete for selection. This competition effect was dominant in ventral temporal cortex. This study provides further evidence for the distinct roles of frontal and temporal cortex in language production, while highlighting the effects of competition, albeit from different sources, in both regions.     

rTMS stimulation on left DLPFC increases the correct recognition of memories for emotional target and distractor words

According to a recent hypothesis, the prefrontal cortex has been proposed as the site of emotional memory integration, because it is sensitive to the recognition of emotional contents. In the present research, we explored the role of the dorsolateral prefrontal cortex (DLPFC) in memory recognition processes for positive versus negative emotional stimuli when old (target) and new (distractor, either semantically related or unrelated to the target) stimuli were presented. The role of the DLPFC was analysed using an rTMS (repeated transcranial magnetic stimulation) paradigm that induced increased cortical activation of the left DLPFC. The subjects were required to perform a task that consisted of two experimental phases (i.e., an encoding and a recognition phase) in which the targets and the distractors were presented and recognition performance was measured. rTMS stimulation was provided over the left DLPFC during the recognition phase. We found that the rTMS stimulation affected the memory recognition of positive emotional material. Moreover, related and unrelated distractors were discarded better when they were positively valenced, and a more significant effect (i.e., increased performance) was produced in response to related distractors. This result suggests that the activation of the left DLPFC favours the memory recognition of positive emotional information, and that such activation is able to induce a more appropriate selective process to distinguish target from distractor stimuli in the presence of more complex processes (related distractors). The valence model of emotional cue processing may explain this increased performance by demonstrating the distinct role of the left hemisphere in the retrieval of positive emotional information.     

Action matters: The role of action plans and object affordances in selection for action

In a series of three experiments requiring selection of real objects for action, we investigated whether characteristics of the planned action and/or the “affordances” of target and distractor objects affected interference caused by distractors. In all ofthe experiments, the target object was selectedon the basis of colour and was presented alone or with a distractor object. We examined the effect of type of response (button press, grasping, or pointing), object affordances (compatibility with the acting hand, affordances for grasping or pointing), and target/distractor positions (left or right) on distractor interference (reaction time differences between trials with and without distractors). Different patterns of distractor interference were associated with different motor responses. In the button-press conditions of each experiment, distractor interference was largely determined by perceptual salience (e.g., proximity to initial visual fixation). In contrast, in tasks requiring action upon the objects in the array, distractors with handles caused greater interference than those without handles, irrespective of whether the intended action was pointing or grasping. Additionally, handled distractors were relatively more salient when their affordances for grasping were strong (handle direction compatible with the acting hand) than when affordances were weak. These data suggest that attentional highlighting of specific target and distractor features is a function of intended actions.     

The functional neuroanatomy of emotion and affective style

Recently, there has been a convergence in lesion and neuroimaging data in the identification of circuits underlying positive and negative emotion in the human brain. Emphasis is placed on the prefrontal cortex (PFC) and the amygdala as two key components of this circuitry. Emotion guides action and organizes behavior towards salient goals. To accomplish this, it is essential that the organism have a means of representing affect in the absence of immediate elicitors. It is proposed that the PFC plays a crucial role in affective working memory. The ventromedial sector of the PFC is most directly involved in the representation of elementary positive and negative emotional states while the dorsolateral PFC may be involved in the representation of the goal states towards which these elementary positive and negative states are directed. The amygdala has been consistently identified as playing a crucial role in both the perception of emotional cues and the production of emotional responses, with some evidence suggesting that it is particularly involved with fear-related negative affect. Individual differences in amygdala activation are implicated in dispositional affective styles and increased reactivity to negative incentives. The ventral striatum, anterior cingulate and insular cortex also provide unique contributions to emotional processing.     

Attentional engagement is not sufficient to prevent spatial capture

What conditions, if any, can fully prevent attentional capture (i.e., involuntary allocation of spatial attention to an irrelevant object) has been a matter of debate. In a previous study, Folk, Ester, and Troemel (Psychonomic Bulletin & Review 16:127–132, 2009) suggested that attentional capture can be blocked entirely when attention is already engaged in a different object. This conclusion relied on the finding that in a search for a known-color target in a rapid serial visual presentation stream, a peripheral distractor with the target color did not further impair target identification performance when a distractor also with the target color that appeared in the stream had already captured attention. In the present study, we argue that this conclusion is unwarranted, because the effects of the central and peripheral distractors could not be disentangled. In order to isolate the effect of the peripheral distractor, we introduced a distractor–target letter compatibility manipulation. Our results showed that the peripheral distractor summoned attention, irrespective of whether attention had just been engaged. We conclude that neither spatially focused attention nor attentional engagement is sufficient to prevent attentional capture.     

The effect of nonmasking distractors on the priming of motor responses

Masked stimuli (primes) can affect the preparation of a motor response to subsequently presented target. In numerous studies, it has been shown that the compatibility effect is biphasic as it develops over time: positive (benefits for compatible trials and costs for incompatible trials) for short prime-target temporal distances and negative (benefits for incompatible trials and costs for compatible trials) for long ones. What triggers the 2nd phase is the matter of the current debate. According to the self-inhibition hypothesis, the motor response elicited by a prime is automatically followed by an inhibition phase. The object-updating and mask-triggered inhibition hypotheses assume that this phase is triggered by the mask, provided that it contains features calling for the alternative response. In the present study, the author shows that the compatibility effect is modulated on the temporal position of a nonmasking distractor presented after the prime and before the target. With a distractor possessing task-relevant features, the compatibility effect was found to be negative for short prime- distractor intervals and for moderate prime-target intervals. The consequences of these results for the 3 hypotheses are discussed.     

Action planning in the presence of distracting stimuli: an investigation into the time course of distractor effects

Humans have a remarkable capability to respond efficiently to a stimulus of interest despite other stimuli competing for neural resources. The current study investigated how the human system copes with distracting stimuli. During each trial, participants viewed 2 sequential stimuli that were each associated with a specific action based on an arbitrary mapping. The 1st stimulus served as a distractor, and the 2nd stimulus required a response (target). When the distractor preceded the target by more than a few hundred milliseconds, response latencies were slower when the 2 stimuli were associated with the same response. The authors propose that this negative compatibility effect stemmed from an inhibitory mechanism that the human system utilizes to prevent the distractor from eliciting an unwanted response.     

社会行为的效价信息对注意捕获的影响：基于帮助和阻碍行为的探讨

采用学习-测验两任务范式, 通过3项实验探讨了社会行为的效价信息对注意捕获的影响。在学习阶段, 被试观看具有积极效价的帮助行为(某智能体帮助另一智能体爬山)和消极效价的阻碍行为(某智能体阻碍另一智能体爬山), 以及与各自运动特性匹配的无社会交互行为, 其目的为建立不同智能体颜色与社会行为效价信息的联结关系。在测验阶段, 则分别检验社会行为中的施动方(帮助者和阻碍者)颜色和受动方(被帮助者和被阻碍者)颜色的注意捕获效应。结果发现, 消极社会行为中施动方颜色和受动方颜色均更容易捕获注意, 而积极社会行为效价信息并没有改变联结特征值的注意捕获效应; 且相比于受动方, 与消极社会行为效价建立联结的施动方颜色的注意捕获效应更强。该结果提示, 存在消极社会行为效价驱动的注意捕获, 且消极的效价信息与卷入社会行为所有个体的特征建立联结, 但该联结中施动方物理特征具有更高的注意优先性。这一发现暗示, 声誉信息与对社会交互行为的整体表征可能综合作用于对社会交互事件的注意选择。     

Investigating the modality specificity of response selection using a temporal flanker task

The neurocognitive architecture for response selection is uncertain. Some theorists suggest that it is mediated by an amodal central mechanism, whereas others propose a set of independent control mechanisms. In a functional neuroimaging experiment, we investigated the nature of response selection by examining how its underlying brain mechanisms are affected by stimulus modality. To do this, we used a modified flanker task, in which the target and flanker (distractor) stimuli differed in time rather than space, making it accessible for both visual and auditory stimuli. As in the traditional flanker task, larger reaction times were observed for incongruent than congruent trials (i.e., a congruency effect) for both modalities. Congruency affected brain activation for both modalities in prefrontal cortex, parietal cortex, and the putamen. Modality-dependent activation was found in additional prefrontal and parietal regions for the visual modality and in left inferior prefrontal cortex for the auditory modality. Modality-dependent activity specifically related to response congruency was also found in sensory cortical regions. These data suggest that modality affects the brain regions throughout the cortex mediating response selection even for conceptually identical stimuli and tasks. They are consistent with the hypothesis that (at least partially) independent brain networks mediate response selection and that input modality may be a powerful factor for organizing neural activity to support task performance.     

Negative priming without reaction time: Effects on identification of masked letters

Responses to an object are often slower and/or less accurate if that object is related to a recently ignored object. Thisnegative priming effect has previously been examined only in reaction time tasks. In the present experiment, target letters and flanking distractor letters were displayed for 33, 100, or 300 msec, followed by a pattern mask. Subjects attempted to identify the target letters, with no demand for speed. Identification accuracy was reduced for targets that matched distractors presented on the immediately preceding trial. However, there was no bias against reporting preceding distractors on catch trials with no presented target. Implications for theories of negative priming are discussed.     

Effects of a moving distractor object on time-to-contact judgments

The effects of moving task-irrelevant objects on time-to-contact (TTC) judgments were examined in 5 experiments. Observers viewed a directly approaching target in the presence of a distractor object moving in parallel with the target. In Experiments 1 to 4, observers decided whether the target would have collided with them earlier or later than a standard (absolute identification task). A contrast effect was observed: If the distractor arrived later than the target, it caused a bias toward early responses, relative to the condition without a distractor. The early-arriving distractor had no significant effect. The pattern of results was unaltered when potentially confounding information from individual visual cues was removed. The availability of stereoscopic information reduced the effect. The contrast effect was also observed if target and distractor were abstract geometric objects rather than simulations of real-world vehicles, rendering less likely a simple safety strategy activated by a potentially threatening distractor. Experiment 5 showed that the effect of the late-arriving distractor generalized to a prediction-motion task. The results indicate that task-irrelevant information in the background has to be considered in revision of time-to-contact theory.     

Response Channel Activation and the Temporoparietal Junction

When we learn to make one motor response to one visual stimulus and a different motor response to another, representations of these stimulus–response associations must be maintained to efficiently transduce perception into action. When an irrelevant distractor is presented adjacent to a target stimulus, interference is observed when the two stimuli are associated with conflicting responses, presumably due to response channel activation by the incompatible information. We have explored the neural bases of these interference effects. In a previous study, patients with hemispatial neglect showed normal interference from contralesional flankers. In another study, patients with lesions of the lateral prefrontal cortex were found not to show interference from distractors presented in the contralesional hemifield. The current study provided a more anatomically detailed investigation of the effects of posterior association cortex lesions on flanker interference. Patients with chronic, unilateral lesions involving the temporoparietal junction (TPJ), two of whom had hemispatial neglect, were compared with patients with lesions of the posterior association cortex not involving the TPJ. All patients performed a color discrimination task at fixation while a congruent or incongruent colored flanker was briefly presented (16.7 ms) in the adjacent contralesional or ipsilesional hemifield. Patients with TPJ lesions showed no interference effects from the contralesional flankers. These results suggest that the TPJ, in combination with the dorsolateral prefrontal cortex, is involved in transducing perception into action.     

情绪大脑机制研究的进展

文章综述情绪大脑机制研究的最新进展。情绪的脑机制——大脑回路,包括前额皮层、杏仁核、海马、前部扣带回、腹侧纹状体等。前额皮层中的不对称性与趋近和退缩系统有关,左前额皮层与趋近系统和积极感情有关,右前额皮层与消极感情和退缩有关。杏仁核易被消极的感情刺激所激活,尤其是恐惧。海马在情绪的背景调节中起着重要作用。前额皮层和杏仁核激活不对称性的个体差异是情绪个体差异的生理基础。情绪的中枢回路有可塑性。     

Influence of attended repetition trials on negative priming in younger and older adults

A lengthened response time when a distractor becomes a target, called negative priming, is an undisputed phenomenon in selective attention, yet just what the underlying mechanism responsible for negative priming is has not been resolved. In this study, the proportion of attended repetition trials was manipulated in order to test the predictions of three theories that have been proposed for explaining spatial negative priming: distractor suppression (e.g., Tipper, 1985), episodic memory retrieval (e.g., Neill, Valdes, &; Terry, 1995), and novelty bias (e.g., Milliken, Tipper, Houghton, &; Lupiáñez, 2000). The results supported the proposal that a novelty bias, which is flexible and can be overridden, is the primary mechanism responsible for priming in spatial tasks. Memory retrieval obscured the novelty bias for target processing, was more selective in older adults, and did not affect distractor processing. Novelty bias and distractor suppression may share the same inhibitory attentional mechanism.     

乐观偏差的认知神经机制

乐观偏差是指人们趋向于认为好事发生在自己身上, 坏事发生在他人身上的一种心理期望(Weinstein, 1980)。乐观偏差的研究范式主要有社会比较范式、过去未来想象范式以及信息转变任务范式。运用fMRI对乐观偏差研究发现, 乐观偏差的神经机制主要涉及前喙扣带皮质和杏仁核、前额叶、多巴胺等。未来要结合社会比较和信息转变范式对乐观偏差进行测量; 研究乐观偏差认知机制的神经机制, 特别是采用ERP技术研究乐观偏差的认知机制; 同时要进一步揭示不同亚型乐观偏差的神经机制; 最后还要开展乐观偏差影响心理健康的神经机制研究。     

Negative priming without probe selection

Responses to an object may be slower or less accurate if that object shares attributes with a recently ignored object(negative priming). Some studies have found negative priming only if the probe trial required selection against a distractor stimulus. In the present experiment, subjects responded to the location of a target (O), ignoring a distractor (X) if it appeared in another location. Reaction time was slower to probe targets that appeared in the same location as the prime distractor, regardless of whether or not the probe target was accompanied by a distractor.     

Understanding other people's actions: intention and attention

This study investigated the extent to which observation of an action performed by a human actor or a robotic arm may kinematically prime the performance of an observer subsequently required to perform a similar action. In Experiment 1, an actor reached for a target presented in isolation or flanked by a distractor object. Subsequently, an observer was required to perform a similar action toward the target object, but always in the absence of the distractor. The kinematics of both the human actor and the observer were affected by the presence of the distractor. Unexpectedly, similar effects were found in the observer's kinematics during the trials in which the actor was seated in front of the observer but no action was demonstrated (catch trials). Results from 4 subsequent experiments suggest that the motor intentions of the actor can be inferred by monitoring his or her gaze. To support this conclusion, results are discussed in terms of recent work spanning many disciplines involved in combining gaze direction and body movements.     

Long-term response-stimulus associations can influence distractor-response bindings

Strong associations between target stimuli and responses usually facilitate fast and effortless reactions. The present study investigated whether long-term associations between distractor stimuli and responses modulate behavior. In particular, distractor stimuli can affect behavior due to distractor-based stimulus-response retrieval, a phenomenon called distractor-response binding: An ignored stimulus becomes temporarily associated with a response and retrieves it at stimulus repetition. In a flanker task, participants ignored left and right pointing arrows and responded to a target letter either with left and right (strongly associated) responses or with upper and lower (weakly associated) responses. Binding effects were modulated in dependence of the long-term association strength between distractors and responses. If the association was strong (arrows pointing left and right with left and right responses), binding effects emerged but only in case of compatible responses. If the long-term association between distractors and responses was weak (arrows pointing left and right with upper and lower responses), binding was weaker and not modulated by compatibility. In contrast, sequential compatibility effects were not modulated by association strength between distractor and response. The results indicate that existing long-term associations between stimuli responses may modulate the impact of an ignored stimulus on action control.     

TRoPICALS: a computational embodied neuroscience model of compatibility effects

Perceiving objects activates the representation of their affordances. For example, experiments on compatibility effects showed that categorizing objects by producing certain handgrips (power or precision) is faster if the requested responses are compatible with the affordance elicited by the size of objects (e.g., small or large). The article presents a neural-network architecture that provides a general framework to account for compatibility effects. The model was designed with a methodological approach (computational embodied neuroscience) that aims to provide increasingly general accounts of brain and behavior (4 sources of constraints are used: neuroscientific data, behavioral data, embodied systems, reproduction of learning processes). The model is based on 4 principles of brain organization that we claim underlie most compatibility effects. First, visual perception and action are organized in the brain along a dorsal neural pathway encoding affordances and a ventral pathway encoding goals. Second, the prefrontal cortex within the ventral pathway gives a top-down bias to action selection by integrating information on stimuli, context, and goals. Third, reaction times depend on dynamic neural competitions for action selection that integrate bottom-up and top-down information. The congruence or incongruence between affordances and goals explains the different reaction times found in the experiments. Fourth, as words trigger internal simulations of their referents, they can cause compatibility effects as objects do. We validated the model by reproducing and explaining 3 types of compatibility effects and showed its heuristic power by producing 2 testable predictions. We also assessed the explicative power of the model by comparing it with related models and showed how it can be extended to account for other compatibility effects.     

The control of visual attention and its influence on prioritized processing in a location negative priming paradigm

In a location-based negative priming paradigm, the possibility of a disengagement option of the underlying inhibitory mechanism was tested. Whereas in previous studies disengagement was observed when providing utility information about the probe trial structure, in the present study the allocation of visual attention to the stimuli was manipulated. In the first step an automatic deployment of visual attention was implemented by presenting all stimuli as abrupt onsets (Experiment 1), which demonstrated commonly observed negative priming effects. In further conditions of non-automatic allocation of visual attention in which target and distractor were presented as no-onset stimuli, negative priming effects were eliminated (Experiments 2 and 3). The preferred interpretation is that in conditions of automatic control of attention, target and distractor compete for control of action. A non-automatic control of visual attention, on the other hand, leads to a top-down modulated selection, which results in prioritized target encoding and a loss of distractor impact on the selection process. Alternative accounts and the role of no-onset distractor processing were investigated in Experiment 4.