Semantic congruency modulates the speed-up of multisensory responses.

Responses to multisensory signals are often faster compared to their unisensory components. This speed-up is typically attributed to target redundancy in that a correct response can be triggered by one or the other signal. In addition, semantic congruency of signals can also modulate multisensory responses; however, the contribution of semantic content is difficult to isolate as its manipulation commonly changes signal redundancy as well. To disentangle the effects of redundancy and semantic congruency, we manipulated semantic content but kept redundancy constant. We presented semantically congruent/incongruent animal pictures and sounds and asked participants to respond with the same response to two target animals (cats and dogs). We find that the speed-up of multisensory responses is larger for congruent (e.g., barking dogs) than incongruent combinations (e.g., barking cats). We then used a computational modelling approach to analyse audio-visual processing interferences that may underlie the effect. Our data is best described by a model that explains the semantic congruency modulation with a parameter that was previously linked to trial sequence effects, which in our experiment occur from the repetition/switching of both sensory modality and animal category. Yet, a systematic analysis of such trial sequence effects shows that the reported congruency effect is an independent phenomenon. Consequently, we discuss potential contributors to the semantic modulation of multisensory responses.

Towards a conflict account of déjà vu: The role of memory errors and memory expectation conflict in the experience of déjà vu.

Déjà vu can be defined as conflict between a subjective evaluation of familiarity and a concurrent evaluation of novelty. Accounts of the déjà vu experience have not explicitly referred to a "conflict account of déjà vu" despite the acceptance of conflict-based definitions of déjà vu and relatively recent neuroimaging work that has implicated brain areas associated with conflict as underpinning the experience. Conflict monitoring functioning follows a similar age-related trajectory to déjà vu with a peak in young adulthood and a subsequent age-related decline. In this narrative review of the literature to date, we consider how déjà vu is defined and how this has influenced the understanding of déjà vu. We also review how déjà vu can be understood within theories of recognition memory and cognitive control. Finally, we summarise the conflict account of déjà vu and propose that this account of the experience may provide a coherent explanation as to why déjà vu experiences tend to decrease with age in the non-clinical population.

Dissociating neural activity associated with the subjective phenomenology of monocular stereopsis: An EEG study.

The subjective phenomenology associated with stereopsis, of solid tangible objects separated by a palpable negative space, is conventionally thought to be a by-product of the derivation of depth from binocular disparity. However, the same qualitative impression has been reported in the absence of disparity, e.g., when viewing pictorial images monocularly through an aperture. Here we aimed to explore if we could identify dissociable neural activity associated with the qualitative impression of stereopsis in the absence of the processing of binocular disparities. We measured EEG activity while subjects viewed pictorial (non-stereoscopic) images of 2D and 3D geometric forms under four different viewing conditions (binocular, monocular, binocular aperture, monocular aperture). EEG activity was analysed by oscillatory source localization (beamformer technique) to examine power change in occipital and parietal regions across viewing and stimulus conditions in targeted frequency bands (alpha: 8-13 Hz & gamma: 60-90 Hz). We observed expected event-related gamma synchronization and alpha desynchronization in occipital cortex and predominant gamma synchronization in parietal cortex across viewing and stimulus conditions. However, only the viewing condition predicted to generate the strongest impression of stereopsis (monocular aperture) revealed significantly elevated gamma synchronization within the parietal cortex for the critical contrasts (3D vs. 2D form). These findings suggest dissociable neural processes specific to the qualitative impression of stereopsis as distinguished from disparity processing.

Exploring the role of self/other perspective-shifting in theory of mind with behavioural and EEG measures.

Theory of Mind (ToM) refers to the ability to compute and attribute mental states to oneself and other people. This study sought to assess the extent of differentiation between "Self" and "Other" in ToM processes, and, of particular importance, the key role of perspective-shifting between "Self" and "Other". Utilizing a newly established false-belief paradigm in a matched design, healthy adult participants completed the task whilst behavioural measures (response times, error rates) and electrophysiological (EEG) recordings were taken. Results revealed that self-oriented belief-attribution was faster and less error-prone than other-oriented belief-attribution, and demonstrated a key role of perspective-shifting. Perspective shifts from Self-to-Other resulted in longer response times and more errors than shifts from Other-to-Self. In contrast, no difference between self and other probes was found in no perspective-shift trials. Reflecting this, EEG recordings showed a significant interaction between Perspective-Shifting and Probe Type at an early onset across right parieto/occipito-lateral areas (250 ms post-stimulus onset), and across frontal-central areas from 500 ms post-stimulus onset, indicating the key role of these areas in ToM engagement. Results demonstrate that "Self" and "Other" can be distinguished at a behavioural level, and highlight the critical role of "Perspective-Shifting" in ToM processes.

Cross-cultural differences in adult Theory of Mind abilities: A comparison of native-English speakers and native-Chinese speakers on the Self/Other Differentiation task.

Theory of Mind (ToM) refers to the ability to compute and attribute mental states to ourselves and other people. It is currently unclear whether ToM abilities are universal or whether they can be culturally influenced. To address this question, this research explored potential differences in engagement of ToM processes between two different cultures, Western (individualist) and Chinese (collectivist), using a sample of healthy adults. Participants completed a computerised false-belief task, in which they attributed beliefs to either themselves or another person, in a matched design, allowing direct comparison between "Self"- and "Other"-oriented conditions. Results revealed that both native-English speakers and native-Chinese individuals responded significantly faster to self-oriented than other-oriented questions. Results also showed that when a trial required a "perspective-shift," participants from both cultures were slower to shift from Self-to-Other than from Other-to-Self. Results indicate that despite differences in collectivism scores, culture does not influence task performance, with similar results found for both Western and non-Western participants, suggesting core and potentially universal similarities in the ToM mechanism across these two cultures.

Eye fixation during multiple object attention is based on a representation of discrete spatial foci.

We often look at and attend to several objects at once. How the brain determines where to point our eyes when we do this is poorly understood. Here we devised a novel paradigm to discriminate between different models of spatial selection guiding fixation. In contrast to standard static attentional tasks where the eye remains fixed at a predefined location, observers selected their own preferred fixation position while they tracked static targets that were arranged in specific geometric configurations and which changed identity over time. Fixations were best predicted by a representation of discrete spatial foci, not a polygonal grouping, simple 2-foci division of attention or a circular spotlight. Moreover, attentional performance was incompatible with serial selection. Together with previous studies, our findings are compatible with a view that attentional selection and fixation rely on shared spatial representations and suggest a more nuanced definition of overt vs. covert attention.

A causal role for the anterior mid-cingulate cortex in negative affect and cognitive control.

Converging evidence has linked the anterior mid-cingulate cortex to negative affect, pain and cognitive control. It has previously been proposed that this region uses information about punishment to control aversively motivated actions. Studies on the effects of lesions allow causal inferences about brain function; however, naturally occurring lesions in the anterior mid-cingulate cortex are rare. In two studies we therefore recruited 94 volunteers, comprising 15 patients with treatment-resistant depression who had received bilateral anterior cingulotomy, which consists of lesions made within the anterior mid-cingulate cortex, 20 patients with treatment-resistant depression who had not received surgery and 59 healthy control subjects. Using the Ekman 60 faces paradigm and two Stroop paradigms, we tested the hypothesis that patients who received anterior cingulotomy were impaired in recognizing negative facial affect expressions but not positive or neutral facial expressions, and impaired in Stroop cognitive control, with larger lesions being associated with more impairment. Consistent with this hypothesis, we found that larger volume lesions predicted more impairment in recognizing fear, disgust and anger, and no impairment in recognizing facial expressions of surprise or happiness. However, we found no impairment in recognizing expressions of sadness. Also consistent with the hypothesis, we found that larger volume lesions predicted impaired Stroop cognitive control. Notably, this relationship was only present when anterior mid-cingulate cortex lesion volume was defined as the overlap between cingulotomy lesion volume and Shackman's meta-analysis-derived binary masks for negative affect and cognitive control. Given substantial evidence from healthy subjects that the anterior mid-cingulate cortex is part of a network associated with the experience of negative affect and pain, engaging cognitive control processes for optimizing behaviour in the presence of such stimuli, our findings support the assertion that this region has a causal role in these processes. While the clinical justification for cingulotomy is empirical and not theoretical, it is plausible that lesions within a brain region associated with the subjective experience of negative affect and pain may be therapeutic for patients with otherwise intractable mood, anxiety and pain syndromes.

The effects of musical training on movement pre-programming and re-programming abilities: an event-related potential investigation.

Two response precuing experiments were conducted to investigate effects of musical skill level on the ability to pre- and re-programme simple movements. Participants successfully used advance information to prepare forthcoming responses and showed response slowing when precue information was invalid rather than valid. This slowing was, however, only observed for partially invalid but not fully invalid precues. Musicians were generally faster than non-musicians, but no group differences in the efficiency of movement pre-programming or re-programming were observed. Interestingly, only musicians exhibited a significant foreperiod lateralized readiness potential (LRP) when response hand was pre-specified or full advance information was provided. These LRP findings suggest increased effector-specific motor preparation in musicians than non-musicians. However, here the levels of effector-specific preparation did not predict preparatory advantages observed in behaviour. In sum, combining the response precuing and ERP paradigms serves a valuable tool to examine influences of musical training on movement pre- or re-programming processes.

From self to social cognition: Theory of Mind mechanisms and their relation to Executive Functioning.

'Theory of Mind' refers to the ability to attribute mental states to oneself and other people (Premack & Woodruff, 1978). This study examined the extent to which 'Self' and 'Other' belief-attribution processes within the Theory of Mind (ToM) mechanism could be distinguished behaviourally, and whether these separable components differentially related to Executive Functioning (EF) abilities. A computerized false-belief task, utilizing a matched-design to allow direct comparison of self-oriented vs. other-oriented belief-attribution, was used to assess ToM, and a face-image Stroop task was employed to assess EF, within a population of typically-developed adults. Results revealed significantly longer reaction times when attributing beliefs to other people as opposed to recognizing and attributing beliefs to oneself. Intriguingly, results revealed that 'perspective-shift' requirements (i.e. changing from adoption of the 'self' perspective to the perspective of the 'other', or vice versa) across false-belief trials influenced reaction times. Reaction times were significantly longer when the perspective shift was from self-to-other than from other-to-self. It is suggested that the 'self' forms the stem of understanding the 'other', and is therefore processed regardless of ultimate task demands; in contrast, the 'other' perspective is only processed when explicitly required. We conclude that adopting another person's perspective, even when their belief state is matched to one's own, requires more cognitive effort than recalling and reflecting on self-oriented belief-states.

Reactive and proactive control adjustments under increased depressive symptoms: insights from the classic and emotional-face Stroop task.

The current research investigated differences in reactive and proactive cognitive control as a function of depressive symptomatology. Three participant groups with varying symptom levels (Beck Depression Inventory-II, BDI-II score) completed both the classic and an emotional-face Stroop task separately under speed and accuracy instructions. All groups made equivalent speed-accuracy trade-offs independent of task, suggesting that proactive adjustments are unaffected by depressive symptoms. Additionally, groups made equivalent reactive control adjustments (Stroop effects, congruency sequence effects) in the classic Stroop task, suggesting that these reactive control adjustments are spared across a wide range of BDI-II scorers. In contrast, the high BDI-II group displayed a selective impairment in the resolution of conflict in the emotional-face Stroop task. Thus, while proactive control and many aspects of reactive control were unaffected by the level of depressive symptoms, specific impairments occurred when current task demands required the trial-to-trial regulation of emotional processing.

Improved effectiveness of performance monitoring in amateur instrumental musicians.

Here we report a cross-sectional study investigating the influence of instrumental music practice on the ability to monitor for and respond to processing conflicts and performance errors. Behavioural and electrophysiological indicators of response monitoring in amateur musicians with various skill levels were collected using simple conflict tasks. The results show that instrumental musicians are better able than non-musicians to detect conflicts and errors as indicated by systematic increases in the amplitude of the error-related negativity and the N200 with increasing levels of instrumental practice. Also, high levels of musical training were associated with more efficient and less reactive responses after experience of conflicts and errors as indicated by reduced post-error interference and post-conflict processing adjustments. Together, the present findings suggest that playing a musical instrument might improve the ability to monitor our behavior and adjust our responses effectively when needed. As these processes are amongst the first to be affected by cognitive aging, our evidence could promote musical activity as a realistic intervention to slow or even prevent age-related decline in frontal cortex mediated executive functioning.

Group membership affects spontaneous mental representation: failure to represent the out-group in a joint action task.

Predicting others' actions is crucial to successful social interaction. Previous research on joint action, based on a reaction-time paradigm called the Joint Simon Task, suggests that successful joint action stems from the simultaneous representation of the self with the other. Performance on this task provides a read-out of the degree of intrusion from a partner that participants experience from acting jointly compared to acting alone, which in turn is a measure of the degree to which participants mentally represent their co-actors during the task. To investigate the role of perceived group membership in this type of joint action and its influence on the representation of others, we first subjected participants to a minimal group paradigm while manipulating differences in social competition. We then asked participants to do the Joint Simon Task in pairs with an in-group or out-group member. Only participants who acted with an "in-group" partner on the joint task showed altered reaction times compared to when acting alone, presumably a change caused by the simultaneous and automatic representation of their in-group partner. In contrast, participants who acted with an out-group partner were unaffected in their reactions when doing the joint task, showing no evidence of representation of their out-group partner. This effect was present in both the high-competition and low-competition conditions, indicating that the differential effects of group membership on representation during joint action were driven by perceived group membership and independent of the effects of social competition. We concluded that participants failed to represent out-group members as socially relevant agents not based on any personality or situational characteristics, but in reaction only to their status as "other". In this way group membership appears to affect cognition on a very immediate and subconscious level.

False external feedback modulates posterror slowing and the f-P300: implications for theories of posterror adjustment.

People tend to slow down after mistakes. This posterror slowing (PES) has commonly been explained by a change to a more conservative response threshold to avoid future errors. Alternatively, the attention-orienting account posits that all infrequent, surprising events (including errors) elicit an orienting response followed by a time-consuming process of task reorientation, explaining PES without increased response caution. In the present study, we employed both behavioral and electrophysiological measures to compare the predictions of these accounts using a flanker paradigm in which accurate or false external response feedback was provided. Participants demonstrated typical posterror adjustments, responding more slowly and accurately in posterror than in postcorrect trials. This finding provides initial evidence suggesting that posterror adjustments are motivated by the avoidance of subsequent mistakes. Most importantly, PES and an event-related potential relating to the attentional processing of feedback, the feedback-related P300 (f-P300), were modulated by feedback type. More specifically, the f-P300 was larger after false than after accurate feedback, suggesting that participants oriented their attention toward (i.e., were surprised by) inaccurate feedback signals. Interestingly, false feedback differentially modulated reaction times: Participants were slower after correct responses when feedback falsely informed of an error rather than confirmed the correct response. In contrast, faster responses were made after errors when feedback falsely indicated correct rather than incorrect performance. When these patterns of results are regarded together, they are best explained by theories of cognitive control in which posterror adjustments in choice reaction time tasks are assumed to reflect control processes leading to more conservative performance after error signals.

Weaker error signals do not reduce the effectiveness of post-error adjustments: comparing error processing in young and middle-aged adults.

In this study we investigated age-related differences in error processing, comparing performance measures and physiological indicators of error processing of middle-aged (41-59years) and young (18-31years) adults using a version of the Eriksen flanker task. Although middle-aged participants were overall slower, both groups showed a comparable decrease in reaction time on error trials as well as slower and more accurate post-error performance. Despite the preserved error speeding and post-error slowing effects, we found an amplitude reduction in the Ne/ERN, contradicting the existence of a direct relationship between the amplitude of this component and post-error adjustments. This was further supported by the lack of significant correlations between the single-trial Ne/ERN amplitude and error-related reaction times. The single-trial Ne/ERN distribution showed a reduced variance for middle-aged compared to young participants, suggesting that weaker overall error signals rather than lapses in error detection are responsible for the observed Ne/ERN amplitude reductions. However, we argue that the signal still reached the necessary threshold to trigger normal post-error adjustments. Finally, the early Pe showed a reduction in amplitude and an increase in latency for middle-aged compared to young adults. Together, the findings suggest clear signs of a physiological decline in error processing at an earlier age than previously known, but these changes do not yet affect implementation of adaptive behavioral changes in middle-aged participants.

"I will fix only my own mistakes": an ERP study investigating error processing in a joint choice-RT task.

The current study investigated error monitoring and subsequent control adjustments in a joint choice RT task. External feedback relating to the combined performance of both actors was provided. Participants slowed down only after their own but not after the co-actor's mistakes. In order to investigate the neural correlates of interpersonal error monitoring, ERPs associated with error processing (Ne/ERN, Pe) and feedback-related processing (FRN, f-P300) were analysed. The Ne/ERN and Pe were only affected by own but not the co-actor's actions. Conversely, at the feedback stage both the FRN and the f-P300 were larger when external feedback indicated a co-actor's error, yet despite this finding, co-actor errors did not affect the actor's subsequent performance. These findings are in line with previous research suggesting that we monitor not only our own but also others' errors. Importantly, however, monitoring others' performance seems insufficient to trigger subsequent behavioural adjustment in the form of post-error slowing, but might only occur when a surprising outcome is evaluated as negative.

Temporal dynamics of trustworthiness perception.

Behavioral and neuroimaging studies suggest that the attribution of trustworthiness to faces relies on emotional and structural cues. Attributions happen spontaneously and very rapidly but the precise temporal dynamics of the underlying processes are not known. We investigated the temporal dynamics of trustworthiness perception by employing scalp recorded event related potentials and evaluating effects on components previously implicated in face processing: P1 (positive component ~100 ms post-stimulus), N170 (negative deflection sensitive to faces) and a posterior-occipital negativity~230 to 280 ms (early posterior negativity-EPN). Participants judged the gender and trustworthiness of female and male images manipulated to look either more or less trustworthy. The results indicated that facilitated behavioral processing of socially important stimuli-in particular males that looked untrustworthy (and should be avoided) but also females that looked trustworthy (and who might therefore be useful in cooperative ventures)-was reflected in an increased negativity of N170 amplitude over the right hemisphere. Additionally, trustworthiness continued to modulate the amplitude of the negative deflection~230 to 280 ms post-stimulus during explicit judgments of trustworthiness but not during gender judgments. The results suggest that negativity accompanies the relevance of the faces (female trustworthy and male untrustworthy) that are important to remember for future social interactions.

Are temporal response features prepared in fixed order? Inferences from movement-related potentials.

Using a response precuing task, we investigated whether motor preparation of temporal response features follows a fixed order as implied by the generalized motor program (GMP) view. Relative timing and overall duration of sequential key presses were factorially manipulated. Precues either provided no information, provided partial information about relative or overall duration, or fully specified the response. Reaction time decreased with the amount of advance information, reflecting the reduction of response alternatives by the precue and influences on preparatory motor processes. The contingent negative variation (CNV) over the left but not the medial and right motor regions increased with the amount of advance information provided. The foreperiod lateralized readiness potential indicated hand-specific activation for the full precue condition only. These findings disagree with the assumption that a GMP's invariant and variable response features are prepared in fixed order.

The implicit identity effect: identity primes, group size, and helping.

Three studies consider the implicit bystander effect in the light of recent advances in social identity approaches to helping. Drawing on the social identity model of deindividuation effects we argue that the implicit bystander effect is shaped not by the number of others imagined, but by who those others are imagined to be. Studies 1 and 2 demonstrate that, when group membership is primed, increasing group size can facilitate helping in line with the norms and values of the group. Study 3 explores mediation processes in group level helping. As group size increases, female participants react faster to words associated with communalism when others are imagined as women rather than strangers. The paper demonstrates that group size and helping behaviour is qualified by an implicit identity effect.

Speeding before and slowing after errors: is it all just strategy?

People are usually faster before and slower after committing an error. This finding has traditionally been explained by strategic changes of response criteria to less or more conservative thresholds. This idea has been implemented in current cognitive control frameworks, where it is proposed that high or low levels of processing conflict can dynamically change these response thresholds to achieve optimal performance. However, recent evidence suggests that evaluation of conflict is time consuming and can potentially interfere with subsequent processing [Jentzsch, I., Dudschig, C., 2009. Why do we slow down after an error? Mechanisms underlying the effects of posterror slowing. Quarterly Journal of Experimental Psychology, 62, 209-218]. The present study aims to extend this finding by investigating whether similar mechanisms underlie effects of pre-error speeding and posterror slowing and whether the amplitude of the Ne/ERN predicts posterror slowing in the current task setting. The response stimulus interval (RSI) was systematically manipulated. Speed-up in pre-error trials was unaffected by RSI, suggesting that this effect is not the result of strategic, time-consuming control processes. Posterror slowing dramatically increased and performance became more error prone with decreasing RSI, providing further evidence for the idea that error evaluation can produce substantial interference with subsequent trial processing, particularly when there is insufficient time between the error and the subsequent event. Importantly, we did not find a positive relationship between the RSI-dependent change in posterror slowing and the Ne/ERN amplitude, questioning a direct link between the amplitude of this component and the amount of subsequent performance adjustments.