Effects of alerting signals on the spatial Stroop effect: evidence for modality differences

Reaction times and error rates to a target's identity are impaired when the target is presented in a location that mismatches the response required, relative to situations where the location of the target and required response overlap (the Simon effect) and the same is true when the target's identity conveys spatial information (the spatial Stroop effect). Prior studies have found that visual versions of the spatial Stroop effect are magnified when alerting cues appear before the target and results are consistent with a dual-route framework where alerting cues boost automatic stimulus-response motor associations through the direct processing route. However, the influence of alerting signals on auditory versions of the spatial Stroop effect have not been tested and there are reasons to believe that the alerting-congruency interaction may differ across stimulus modality. In two experiments the effects of alerting cues on auditory (Experiment 1; N = 98) and visual (Experiment 2; N = 97) spatial Stroop effects are examined. Results show that alerting cues boost the spatial Stroop effect with visual stimuli but not auditory stimuli and a distributional analysis provides support for there being modality differences in the decay (or inhibition) of response-code activation. Implications for explanations of the alerting-congruence interaction are discussed.

Is the alerting-congruency interaction that is seen in experiments with stimulus-response motor associations moderated by a concurrent working-memory load?

The mechanisms underlying attention, distraction, and cognitive control have been widely studied, and results consistently show that reaction times are affected by alerting cues as well as by concurrent distraction. In addition, when distractors have pre-existing directional motor associations, alerting and distractor congruency interact in a manner where distractors have a larger effect when people are alerted to an upcoming target relative to when people are not alerted to the target's presentation. However, does a concurrent working memory load moderate this interaction in multitasking experiments, and if so, does it magnify or suppress this effect? The current study (N = 40) finds that although a memory-load significantly slows reaction times it does not moderate the alerting-congruency interaction. Discussion focuses on theoretical and applied implications of this empirical result.

Neural Mechanisms of Subliminal Mentor-Student Relationship Stimuli Processing: An ERP Study

In educational contexts, mentorship roles often complicate the mentor-student relationship because mentors act not only as the closest academic ally of graduate students but also their program supervisors who can affect their timely graduation. This study examines how graduate students react to their mentors’ names when subliminally presented. A total of 63 graduate students (31 male; Mean Age = 23.450) were asked to perform an irrelevant color judgment task of valenced words (positive vs. negative relationship words) after a subliminal presentation of three different types of names (i.e., mentors, authorities, and friends). Results show that mentor and friend names elicit a greater P2 peak than authority names, whereas mentor names evoke a reduced N2 and P3 amplitude than friend and authority names. In addition, participants with a history of abusive supervision tend to have an overall decline in P2 amplitude. These event-related potential (ERP) findings suggest that mentors are perceived by students as familiar while attention-inducing figures.

Persistence of the "Moving Things Are Alive" Heuristic into Adulthood: Evidence from EEG

Although a growing number of studies indicate that simple strategies, intuitions, or cognitive shortcuts called heuristics can persistently interfere with scientific reasoning in physics and chemistry, the persistence of heuristics related to learning biology is less known. In this study, we investigate the persistence of the "moving things are alive" heuristic into adulthood with 28 undergraduate students who were asked to select between two images, one of which one represented a living thing, while their electroencephalographic signals were recorded. Results show that N2 and LPP event-related potential components, often associated with tasks requiring inhibitory control, are higher in counterintuitive trials (i.e., in trials including moving things not alive or nonmoving things alive) compared with intuitive ones. To our knowledge, these findings represent the first neurocognitive evidence that the "moving things are alive" heuristic persists into adulthood and that overcoming this heuristic might require inhibitory control. Potential implications for life science education are discussed.

Anodal tDCS modulates specific processing codes during conflict monitoring associated with superior and middle frontal cortices

Conflict monitoring processes are central for cognitive control. Neurophysiological correlates of conflict monitoring (i.e. the N2 ERP) likely represent a mixture of different cognitive processes. Based on theoretical considerations, we hypothesized that effects of anodal tDCS (atDCS) in superior frontal areas affect specific subprocesses in neurophysiological activity during conflict monitoring. To investigate this, young healthy adults performed a Simon task while EEG was recorded. atDCS and sham tDCS were applied in a single-blind, cross-over study design. Using temporal signal decomposition in combination with source localization analyses, we demonstrated that atDCS effects on cognitive control are very specific: the detrimental effect of atDCS on response speed was largest in case of response conflicts. This however only showed in aspects of the decomposed N2 component, reflecting stimulus-response translation processes. In contrast to this, stimulus-related aspects of the N2 as well as purely response-related processes were not modulated by atDCS. EEG source localization analyses revealed that the effect was likely driven by activity modulations in the superior frontal areas, including the supplementary motor cortex (BA6), as well as middle frontal (BA9) and medial frontal areas (BA32). atDCS did not modulate effects of proprioceptive information on hand position, even though this aspect is known to be processed within the same brain areas. Physiological effects of atDCS likely modulate specific aspects of information processing during cognitive control.

Phasic alerting facilitates endogenous orienting of spatial attention: Evidence from event-related lateralizations of the EEG

Alerting has been hypothesized to affect spatial orienting either by accelerating the speed of attentional shift toward the cued target location (the accelerating hypothesis) or by enhancing the orienting effect without changing its time course (the enhancing hypothesis). To investigate the neural underpinnings of the effect of phasic alerting on endogenous orienting, we recorded the electroencephalogram (EEG) in a variant of the spatial cueing task with a tone presented 100 ms before the cue as a phasic alerting signal, and calculated cue-evoked event-related lateralizations (ERLs) providing a precise assessment of preparatory visuospatial attention. Behavioral results showed that the spatial orienting effect was increased under the phasic alerting condition, as expected. The EEG results showed that an orienting-related ERL component called a late directing attention positivity (LDAP) had shorter onset latency and larger amplitude in the alerting condition than in the no-alerting (no-tone) condition. In conclusion, phasic alerting seems to both accelerate and enhance orienting-related preparatory modulations within the ventral visual stream.

The neurocognitive underpinnings of the Simon effect: An integrative review of current research

For as long as half a century the Simon task - in which participants respond to a nonspatial stimulus feature while ignoring its position - has represented a very popular tool to study a variety of cognitive functions, such as attention, cognitive control, and response preparation processes. In particular, the task generates two theoretically interesting effects: the Simon effect proper and the sequential modulations of this effect. In the present study, we review the main theoretical explanations of both kinds of effects and the available neuroscientific studies that investigated the neural underpinnings of the cognitive processes underlying the Simon effect proper and its sequential modulation using electroencephalogram (EEG) and event-related brain potentials (ERP), transcranial magnetic stimulation (TMS), and functional magnetic resonance imaging (fMRI). Then, we relate the neurophysiological findings to the main theoretical accounts and evaluate their validity and empirical plausibility, including general implications related to processing interference and cognitive control. Overall, neurophysiological research supports claims that stimulus location triggers the creation of a spatial code, which activates a spatially compatible response that, in incompatible conditions, interferes with the response based on the task instructions. Integration of stimulus-response features plays a major role in the occurrence of the Simon effect (which is manifested in the selection of the response) and its modulation by sequential congruency effects. Additional neural mechanisms are involved in supporting the correct and inhibiting the incorrect response.

Conflict monitoring and the affective-signaling hypothesis-An integrative review

Conflict-monitoring theory proposes that conflict between incompatible responses is registered by a dedicated monitoring system, and that this conflict signal triggers changes of attentional filters and adapts control processes according to the current task demands. Extending the conflict-monitoring theory, it has been suggested that conflict elicits a negative affective reaction, and that it is this affective signal that is monitored and then triggers control adaptation. This review article summarizes research on a potential signaling function of affect for cognitive control. First, we provide an overview of the conflict-monitoring theory, discuss neurophysiological and behavioral markers of monitoring and control adaptation, and introduce the affective-signaling hypothesis. In a second part, we review relevant studies that address the questions of (i) whether conflict elicits negative affect, (ii) whether negative affect is monitored, and (iii) whether affect modulates control. In sum, the reviewed literature supports the claim that conflict and errors trigger negative affect and provides some support for the claim that affect modulates control. However, studies on the monitoring of negative affect and the influence of phasic affect on control are ambiguous. On the basis of these findings, in a third part, we critically reassess the affective-signaling hypothesis, discuss relevant challenges to this account, and suggest future research strategies.

Applying deep learning to single-trial EEG data provides evidence for complementary theories on action control

Efficient action control is indispensable for goal-directed behaviour. Different theories have stressed the importance of either attention or response selection sub-processes for action control. Yet, it is unclear to what extent these processes can be identified in the dynamics of neurophysiological (EEG) processes at the single-trial level and be used to predict the presence of conflicts in a given moment. Applying deep learning, which was blind to cognitive theory, on single-trial EEG data allowed to predict the presence of conflict in ~95% of subjects ~33% above chance level. Neurophysiological features related to attentional and motor response selection processes in the occipital cortex and the superior frontal gyrus contributed most to prediction accuracy. Importantly, deep learning was able to identify predictive neurophysiological processes in single-trial neural dynamics. Hence, mathematical (artificial intelligence) approaches may be used to foster the validation and development of links between cognitive theory and neurophysiology of human behavior.

Vahid et al. use a deep-learning approach to analyze single-trial EEG data to examine theories on action control. Their approach enables the identification of spatial and temporal neurophysiological features that are predictive of the response control during the Simon task. The results confirm cognitive theory-driven approaches on the relationship between neurophysiology and human behavior.

Low and high stimulation frequencies differentially affect automated response selection in the superior parietal cortex - implications for somatosensory area processes

Response inhibition as a central facet of executive functioning is no homogeneous construct. Interference inhibition constitutes a subcomponent of response inhibition and refers to inhibitory control over responses that are automatically triggered by irrelevant stimulus dimensions as measured by the Simon task. While there is evidence that the area-specific modulation of tactile information affects the act of action withholding, effects in the context of interference inhibition remain elusive. We conducted a tactile version of the Simon task with stimuli designed to be predominantly processed in the primary (40 Hz) or secondary (150 Hz) somatosensory cortex. On the basis of EEG recordings, we performed signal decomposition and source localization. Behavioral results reveal that response execution is more efficient when sensory information is mainly processed via SII, compared to SI sensory areas during non-conflicting trials. When accounting for intermingled coding levels by temporally decomposing EEG data, the results show that experimental variations depending on sensory area-specific processing differences specifically affect motor and not sensory processes. Modulations of motor-related processes are linked to activation differences in the superior parietal cortex (BA7). It is concluded that the SII cortical area supporting cognitive preprocessing of tactile input fosters automatic tactile information processing by facilitating stimulus-response mapping in posterior parietal regions.

Funny kittens: Positive mood induced via short video-clips affects error processing but not conflict control

The interplay of performance monitoring functions and affective variables labeled as moods or emotions has been investigated within different theoretical frameworks including conflict adaptation and reinforcement learning. However, results regarding the electrophysiological underpinnings of performance monitoring such as the error-related negativity (ERN), the N200 or the error positivity (Pe) remain largely inconsistent. While some studies report ERN enhancements after positive mood induction, others find reductions due to positive affect. An additional source of complexity regards the manifold induction methods across studies. Here, we investigated whether performance-independent, blocked mood inductions via mini-clips alter electrophysiological markers of performance monitoring. Positive clips consisted of a pre-rated collection of human and animal funny/fail videos, while neutral clips showed natural scenes of humans and animals or sport events. The main task was a modified flanker paradigm. The effectivity of mood induction was confirmed via recorded skin conductance response (SCR), facial-muscle electromyogram (EMG) and intermittent subjective mood questionnaires. Regarding interference control neither reaction times nor error rates were influenced by mood induction, similarly no mood effects of the N2 component were observed. In contrast, we found enhanced ERN as well as Pe amplitudes in the positive compared to the neutral condition. Additional to post error slowing we found increased interference effects after errors in positive blocks on the behavioral level. The results suggest a specific receptiveness of evaluative control components to positive affect that will be discussed regarding their possible neuronal underpinnings.

Transcutaneous vagus nerve stimulation (tVNS) enhances conflict-triggered adjustment of cognitive control

Response conflicts play a prominent role in the flexible adaptation of behavior as they represent context-signals that indicate the necessity for the recruitment of cognitive control. Previous studies have highlighted the functional roles of the affectively aversive and arousing quality of the conflict signal in triggering the adaptation process. To further test this potential link with arousal, participants performed a response conflict task in two separate sessions with either transcutaneous vagus nerve stimulation (tVNS), which is assumed to activate the locus coeruleus-noradrenaline (LC-NE) system, or with neutral sham stimulation. In both sessions the N2 and P3 event-related potentials (ERP) were assessed. In line with previous findings, conflict interference, the N2 and P3 amplitude were reduced after conflict. Most importantly, this adaptation to conflict was enhanced under tVNS compared to sham stimulation for conflict interference and the N2 amplitude. No effect of tVNS on the P3 component was found. These findings suggest that tVNS increases behavioral and electrophysiological markers of adaptation to conflict. Results are discussed in the context of the potentially underlying LC-NE and other neuromodulatory (e.g., GABA) systems. The present findings add important pieces to the understanding of the neurophysiological mechanisms of conflict-triggered adjustment of cognitive control.

Are eyes special? Electrophysiological and behavioural evidence for a dissociation between eye-gaze and arrows attentional mechanisms

It has been proposed that attention triggered by eye-gaze may represent a unique attentional process, different from that triggered by non-social stimuli such as arrows. To investigate this issue, in the present study we compared the temporal dynamics of the conflict processing triggered by eye-gaze and arrow stimuli. We investigated the electrophysiological activity during a task in which participants were required to identify the direction of laterally presented eye-gaze or arrow targets. Opposite behavioural effects were observed: while arrows produced the typical effect, with faster responses when they were congruent with their position, eye-gaze targets produced a reversed effect with faster responses when they were incongruent. Event-related potentials showed common and dissociable congruency modulation: whereas eye-gaze and arrows showed similar effects on earlier ERP components (P1 and N1), they led to opposite effects in later components such as N2 and P3. This represents the first electrophysiological demonstration of both early shared and later dissociable congruency effects for eye-gaze and arrow stimuli.

RETRACTED: Neurophysiological mechanisms underlying the modulation of cognitive control by simultaneous conflicts

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal) This article has been retracted at the request of the Editor-in-Chief with the agreement of the authors. In a previous version of the paper reviewed in another journal, the reviewer suggested changing the filter settings because the setting used (reported hp 0.5) can produce serious artifactual effects on the ERP components (N200, N400 and P300) that the authors were interested in. In this published version of the article a different filter (0.2Hz HP) setting is reported in the methods. However, the results sections are identical. A change in filter setting should have led to different results. There is reasonable doubt that the reported filter settings were indeed applied on the reported data. However, there is consensus that this was due to an error, acknowledged by the authors who fully co-operated with the investigation and agreed with the decision. There is no indication of any fraudulent motivation.

Do alerting signals increase the size of the attentional focus?

Previous research has shown that the presentation of an auditory alerting signal before a visual target increases the interference from flanking distractors. Recently, it has been suggested that this increase in interference may be due to an expansion of the spatial focus of attention. In five experiments, this hypothesis was tested by using a probe technique dedicated to measuring variations in the size of the attentional focus: In the majority of trials, participants performed a letter discrimination task in which their attention was focused on a central target letter. In a randomly intermixed probe task, the size of the attentional focus was measured by letting participants respond to a probe occurring at varying positions. In all experiments, reaction time (RT) to the probe increased from the most central to more lateral probe positions. This V-shaped probe-RT function, however, was not flattened by the presentation of an alerting signal. Overall, this pattern of results is inconsistent with the hypothesis that alerting signals increase the attentional focus. Instead, it is consistent with nonspatial accounts that attribute the increase in interference to an alerting effect on perceptual processing, which then leads to a detrimental effect at the level of response selection.

RLS patients show better nocturnal performance in the Simon task due to diminished visuo-motor priming

OBJECTIVE

The restless legs syndrome (RLS) is characterized by sensory-motor symptoms which usually occur predominantly at rest in the evening and at night. It is assumed that this circadian rhythm is caused by low dopamine levels in the evening. Yet, it has never been investigated whether RLS patients show diurnal variations in cognitive functions modulated by dopamine and what neurophysiological and functional neuroanatomical processes underlie such modulations.

METHODS

We used a Simon task combined with EEG and source localization to investigate whether top-down response selection and/or automatic visuo-motor priming are subject to diurnal changes in RLS patients, as compared to matched healthy controls.

RESULTS

We found that RLS patients showed better task performance due to reduced visuo-motor priming in the evening, as reflected by smaller early lateralized readiness potential (e-LRP) amplitudes and decreased activation of the superior parietal cortex and premotor cortex. Top-down response selection and early attentional processing were unaffected by RLS.

CONCLUSIONS

Counterintuitively, RLS patients show enhanced task performance in the evening, i.e. when experiencing dopaminergic deficiency. Yet, this may be explained by deficits in visuo-motor priming that lead to reduced false response tendencies.

SIGNIFICANCE

This study reveals a counterintuitive circadian variation of cognitive functions in RLS patients.

Differential effects of phasic and tonic alerting on the efficiency of executive attention

The study examined how alerting and executive attention interact in a task involving conflict resolution. We proposed a tentative scenario in which an initial exogenous phasic alerting phase is followed by an endogenous tonic alerting phase, and hypothesized that these two processes may have distinct effects on conflict resolution. Phasic alerting was expected to increase the conflict, whereas tonic alerting was expected to decrease the conflict. Three experiments were conducted using different variants of the flanker task with visual alerting cues and varied cue-target intervals (SOA), to differentiate between effects of phasic alerting (short SOA) and tonic alerting (long SOA). The results showed that phasic alerting consistently decreased the efficiency of conflict resolution indexed by response time and accuracy, whereas tonic alerting increased the accuracy of conflict resolution, but at a cost in the speed of processing the conflict. The third experiment additionally showed that the effects of phasic alerting may be modulated by the psychophysical strength of alerting cues. Discussed are possible mechanisms that could account for the observed interactions between alerting and conflict resolution, as well as some discrepancies between the current and previous studies.

Cognitive control, dynamic salience, and the imperative toward computational accounts of neuromodulatory function

We draw attention to studies indicating that phasic arousal increases interference effects in tasks necessitating the recruitment of cognitive control. We suggest that arousal-biased competition models such as GANE (glutamate amplifies noradrenergic effects) may be able to explain these findings by taking into account dynamic, within-trial changes in the relative salience of task-relevant and task-irrelevant features. However, testing this hypothesis requires a computational model.

Reliable Attention Network Scores and Mutually Inhibited Inter-network Relationships Revealed by Mixed Design and Non-orthogonal Method

The attention system can be divided into alerting, orienting, and executive control networks. The efficiency and independence of attention networks have been widely tested with the attention network test (ANT) and its revised versions. However, many studies have failed to find effects of attention network scores (ANSs) and inter-network relationships (INRs). Moreover, the low reliability of ANSs can not meet the demands of theoretical and empirical investigations. Two methodological factors (the inter-trial influence in the event-related design and the inter-network interference in orthogonal contrast) may be responsible for the unreliability of ANT. In this study, we combined the mixed design and non-orthogonal method to explore ANSs and directional INRs. With a small number of trials, we obtained reliable and independent ANSs (split-half reliability of alerting: 0.684; orienting: 0.588; and executive control: 0.616), suggesting an individual and specific attention system. Furthermore, mutual inhibition was observed when two networks were operated simultaneously, indicating a differentiated but integrated attention system. Overall, the reliable and individual specific ANSs and mutually inhibited INRs provide novel insight into the understanding of the developmental, physiological and pathological mechanisms of attention networks, and can benefit future experimental and clinical investigations of attention using ANT.

Accessory stimulus modulates executive function during stepping task

When multiple sensory modalities are simultaneously presented, reaction time can be reduced while interference enlarges. The purpose of this research was to examine the effects of task-irrelevant acoustic accessory stimuli simultaneously presented with visual imperative stimuli on executive function during stepping. Executive functions were assessed by analyzing temporal events and errors in the initial weight transfer of the postural responses prior to a step (anticipatory postural adjustment errors). Eleven healthy young adults stepped forward in response to a visual stimulus. We applied a choice reaction time task and the Simon task, which consisted of congruent and incongruent conditions. Accessory stimuli were randomly presented with the visual stimuli. Compared with trials without accessory stimuli, the anticipatory postural adjustment error rates were higher in trials with accessory stimuli in the incongruent condition and the reaction times were shorter in trials with accessory stimuli in all the task conditions. Analyses after division of trials according to whether anticipatory postural adjustment error occurred or not revealed that the reaction times of trials with anticipatory postural adjustment errors were reduced more than those of trials without anticipatory postural adjustment errors in the incongruent condition. These results suggest that accessory stimuli modulate the initial motor programming of stepping by lowering decision threshold and exclusively under spatial incompatibility facilitate automatic response activation. The present findings advance the knowledge of intersensory judgment processes during stepping and may aid in the development of intervention and evaluation tools for individuals at risk of falls.

Electrophysiological dynamics reveal distinct processing of stimulus-stimulus and stimulus-response conflicts

The present study examined electroencephalogram profiles on a novel stimulus-response compatibility (SRC) task in order to elucidate the distinct brain mechanisms of stimulus-stimulus (S-S) and stimulus-response (S-R) conflict processing. The results showed that the SRC effects on reaction times (RTs) and N2 amplitudes were additive when both S-S and S-R conflicts existed. We also observed that, for both RTs and N2 amplitudes, the conflict adaptation effects-the reduced SRC effect following an incongruent trial versus a congruent trial-were present only when two consecutive trials involved the same type of conflict. Time-frequency analysis revealed that both S-S and S-R conflicts modulated power in the theta band, whereas S-S conflict additionally modulated power in the alpha and beta bands. In summary, our findings provide insight into the domain-specific conflict processing and the modular organization of cognitive control.

Evaluation of the attention network test using vibrotactile stimulations

We report a vibrotactile version of the attention network test (ANT)-the tactile ANT (T-ANT). It has been questioned whether attentional components are modality specific or not. The T-ANT explores alertness, orienting, cognitive control, and their relationships, similar to its visual counterpart, in the tactile modality. The unique features of the T-ANT are in utilizing stimuli on a single plane-the torso-and replacing the original imperative flanker task with a tactile Simon task. Subjects wore a waist belt mounted with two vibrotactile stimulators situated on the back and positioned to the right and left of the spinal column. They responded by pressing keys with their right or left hand in reaction to the type of vibrotactile stimulation (pulsed/continuous signal). On a single trial, an alerting tone was followed by a short tactile (informative/noninformative) peripheral cue and an imperative tactile Simon task target. The T-ANT was compared with a variant of the ANT in which the flanker task was replaced with a visual Simon task. Experimental data showed effects of orienting over control only when the peripheral cues were informative. In contrast to the visual task, interactions between alertness and control or alertness and orienting were not found in the tactile task. A possible rationale for these results is discussed. The T-ANT allows examination of attentional processes among patients with tactile attentional deficits and patients with eyesight deficits who cannot take part in visual tasks. Technological advancement would enable implementation of the T-ANT in brain-imaging studies.

Priming by the variability of visual information

According to recent theories, perception relies on summary representations that encode statistical information about the sensory environment. Here, we used perceptual priming to characterize the representations that mediate categorization of a complex visual array. Observers judged the average shape or color of a target visual array that was preceded by an irrelevant prime array. Manipulating the variability of task-relevant and task-irrelevant feature information in the prime and target orthogonally, we found that observers were faster to respond when the variability of feature information in the prime and target arrays matched. Critically, this effect occurred irrespective of whether the element-by-element features in the prime and target array overlapped or not, and was even present when prime and target features were drawn from opposing categories. This "priming by variance" phenomenon occurred with prime-target intervals as short as 100 ms. Further experiments showed that this effect did not depend on resource allocation, and occurred even when prime and target did not share the same spatial location. These results suggest that human observers adapt to the variability of visual information, and provide evidence for the existence of a low-level mechanism by which the range or dispersion of visual information is rapidly extracted. This information may in turn help to set the gain of neuronal processing during perceptual choice.

Lateralization of spatial information processing in response monitoring

The current study aims at identifying how lateralized multisensory spatial information processing affects response monitoring and action control. In a previous study, we investigated multimodal sensory integration in response monitoring processes using a Simon task. Behavioral and neurophysiologic results suggested that different aspects of response monitoring are asymmetrically and independently allocated to the hemispheres: while efference-copy-based information on the motor execution of the task is further processed in the hemisphere that originally generated the motor command, proprioception-based spatial information is processed in the hemisphere contralateral to the effector. Hence, crossing hands (entering a “foreign” spatial hemifield) yielded an augmented bilateral activation during response monitoring since these two kinds of information were processed in opposing hemispheres. Because the traditional Simon task does not provide the possibility to investigate which aspect of the spatial configuration leads to the observed hemispheric allocation, we introduced a new “double crossed” condition that allows for the dissociation of internal/physiological and external/physical influences on response monitoring processes. Comparing behavioral and neurophysiologic measures of this new condition to those of the traditional Simon task setup, we could demonstrate that the egocentric representation of the physiological effector's spatial location accounts for the observed lateralization of spatial information in action control. The finding that the location of the physical effector had a very small influence on response monitoring measures suggests that this aspect is either less important and/or processed in different brain areas than egocentric physiological information.

Conflict-Specific Effects of Accessory Stimuli on Cognitive Control in the Stroop Task and the Simon Task

Both the Stroop and the Simon paradigms are often used in research on cognitive control, however, there is evidence that dissociable control processes are involved in these tasks: While conflicts in the Stroop task may be resolved mainly by enhanced task-relevant stimulus processing, conflicts in the Simon task may be resolved rather by suppressing the influence of task-irrelevant information on response selection. In the present study, we show that these control mechanisms interact in different ways with the presentation of accessory stimuli. Accessory stimuli do not affect cognitive control in the Simon task, but they impair the efficiency of cross-trial control processes in the Stroop task. Our findings underline the importance of differentiating between different types of conflicts and mechanisms of cognitive control.

The effects of alerting signals in masked priming

Alerting signals often serve to reduce temporal uncertainty by predicting the time of stimulus onset. The resulting response time benefits have often been explained by facilitated translation of stimulus codes into response codes on the basis of established stimulus-response (S-R) links. In paradigms of masked S-R priming alerting signals also modulate response activation processes triggered by subliminally presented prime stimuli. In the present study we tested whether facilitation of visuo-motor translation processes due to alerting signals critically depends on established S-R links. Alerting signals resulted in significantly enhanced masked priming effects for masked prime stimuli that included and that did not include established S-R links (i.e., target vs. novel primes). Yet, the alerting-priming interaction was more pronounced for target than for novel primes. These results suggest that effects of alerting signals on masked priming are especially evident when S-R links between prime and target exist. At the same time, an alerting-priming interaction also for novel primes suggests that alerting signals also facilitate stimulus-response translation processes when masked prime stimuli provide action-trigger conditions in terms of programmed S-R links.

N1 and N2 ERPs reflect the regulation of automatic approach tendencies to positive stimuli

The Approach-Avoidance Task (AAT) measures automatic approach-avoidance tendencies and their regulation: compatible reactions (approach positive, avoid negative) are faster than incompatible ones (approach negative, avoid positive). The present study assessed event-related potentials (ERPs) in 15 healthy persons for depicting neuropsychological sub-processes of such stimulus-response compatibility (SRC) effects. Early attention allocation preparing efficient stimulus classification (N1 ERP) and response inhibition on the level of response representations (N2 ERP) were found to underlie the solution of the AAT-conflict. For positive stimuli, these processes were enhanced during the incompatible condition avoid positive compared to the compatible condition approach positive. Source localization analysis revealed activity in right occipital areas (N1 ERP), and in left DLPFC and insula (N2 ERP) to be neuronal generators of these electrophysiological SRC effects. This neuronal regulation resulted in no influence of incompatibility at the behavioural level. For negative pictures, we found the reversed pattern: there were no electrophysiological SRC effects, but clear behavioural SRC effects in both RTs and error frequency, i.e. participants were faster and made fewer errors during avoiding than approaching negative pictures. These valence-specific differences are in line with previous studies indicating negative stimuli - probably due to higher importance for survival - to more strongly influence behaviour.

How the emotional content of discourse affects language comprehension

Emotion effects on cognition have often been reported. However, only few studies investigated emotional effects on subsequent language processing, and in most cases these effects were induced by non-linguistic stimuli such as films, faces, or pictures. Here, we investigated how a paragraph of positive, negative, or neutral emotional valence affects the processing of a subsequent emotionally neutral sentence, which contained either semantic, syntactic, or no violation, respectively, by means of event-related brain potentials (ERPs). Behavioral data revealed strong effects of emotion; error rates and reaction times increased significantly in sentences preceded by a positive paragraph relative to negative and neutral ones. In ERPs, the N400 to semantic violations was not affected by emotion. In the syntactic experiment, however, clear emotion effects were observed on ERPs. The left anterior negativity (LAN) to syntactic violations, which was not visible in the neutral condition, was present in the negative and positive conditions. This is interpreted as reflecting modulatory effects of prior emotions on syntactic processing, which is discussed in the light of three alternative or complementary explanations based on emotion-induced cognitive styles, working memory, and arousal models. The present effects of emotion on the LAN are especially remarkable considering that syntactic processing has often been regarded as encapsulated and autonomous.

Functional significance of the emotion-related late positive potential

The late positive potential (LPP) is an event-related potential (ERP) component over visual cortical areas that is modulated by the emotional intensity of a stimulus. However, the functional significance of this neural modulation remains elusive. We conducted two experiments in which we studied the relation between LPP amplitude, subsequent perceptual sensitivity to a non-emotional stimulus (Experiment 1) and visual cortical excitability, as reflected by P1/N1 components evoked by this stimulus (Experiment 2). During the LPP modulation elicited by unpleasant stimuli, perceptual sensitivity was not affected. In contrast, we found some evidence for a decreased N1 amplitude during the LPP modulation, a decreased P1 amplitude on trials with a relatively large LPP, and consistent negative (but non-significant) across-subject correlations between the magnitudes of the LPP modulation and corresponding changes in d-prime or P1/N1 amplitude. The results provide preliminary evidence that the LPP reflects a global inhibition of activity in visual cortex, resulting in the selective survival of activity associated with the processing of the emotional stimulus.