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Narcissists are typically described as egocentric, meaning they behave and think without considering what others might think or feel, which led authors to claim that narcissists’ interpersonal difficulties stem from reduced perspective-taking abilities; a claim supported by self-reported measures of perspective taking. This study examined perspective-taking performance via a visual perspective-taking task along with the Narcissistic Personality Inventory (NPI; Raskin & Terry, 1988) and the Narcisistic Admiration and Rivalry Questionnaire (NARQ; Back et al., 2013). The task was designed to measure the ability to handle conflicting viewpoints and the attentional priority given to the egocentric perspective (i.e., self-centered) versus the altercentric perspective (i.e., another person’s). We found (N=99) and replicated (N=149) that individuals scoring high on narcissism were not more egocentric than individuals scoring low on narcissism; they actually prioritized less their egocentric viewpoint. The narcissists’ higher perspective-taking performance is interpreted and tested in terms of social competency through leadership, social comparisons to get ahead of others, and a deep need of others to self-regulate. When assessing social skills in relation to narcissism, it is essential to use performed-based measures rather than solely rely on self-reports.

Theory of mind (ToM), the ability to understand that other agents have different beliefs, desires, and knowledge than oneself, has been extensively researched. Theory of mind tasks involve participants dealing with interference between their self-perspective and another agent’s perspective, and this interference has been related to executive function, particularly to inhibitory control. This study assessed whether there are individual differences in self–other interference, and whether these effects are due to individual differences in executive function. A total of 142 participants completed two ToM (the director task and a Level 1 visual perspective-taking task), which both involve self–other interference, and a battery of inhibitory control tasks. The relationships between the tasks were examined using path analysis. Results showed that the self–other interference effects of the two ToM tasks were dissociable, with individual differences in performance on the ToM tasks being unrelated and performance in each predicted by different inhibitory control tasks. We suggest that self–other differences are part of the nature of ToM tasks, but self–other interference is not a unitary construct. Instead, self–other differences result in interference effects in various ways and at different stages of processing, and these effects may not be a major limiting step for adults’ performance on typical ToM tasks. Further work is needed to assess other factors that may limit adults’ ToM performance and hence explain individual differences in social ability. Electronic supplementary material The online version of this article (10.3758/s13423-019-01656-z) contains supplementary material, which is available to authorized users.

Thinking about how other people represent objects in the world around them is thought to require deliberate effort. In recent years, interactive "joint action" paradigms have shown how social context can affect our cognitive processing. We tested whether people would represent their partner's point of view in a simple team game. Participants played a game in which they had to judge the magnitude of a number either sat alone, or opposite a partner. Importantly they were never asked to judge their partner's point of view. Remarkably, when playing the game as a team, people were better when their partner happened to share their view of the number, such as when seeing a number 8, than when their partner viewed the number to be different, such as when seeing a number 6 that looked like a number 9 to their partner. In two further experiments, we identified the conditions under which the effect was present. Experiment two showed that the effect was only present after observing the prior involvement of one's partner in the task. Experiment 3, showed that the aspect of the stimulus (its magnitude) that participants were sensitive to did not need to be the aspect of the stimulus to which their partner was paying attention.

Two paradigms have shown that people automatically compute what or where another person is looking at. In the visual perspective-taking paradigm, participants judge how many objects they see; whereas, in the gaze cueing paradigm, participants identify a target. Unlike in the former task, in the latter task, the influence of what or where the other person is looking at is only observed when the other person is presented alone before the task-relevant objects. We show that this discrepancy across the two paradigms is not due to differences in visual settings (Experiment 1) or available time to extract the directional information (Experiment 2), but that it is caused by how attention is deployed in response to task instructions (Experiment 3). Thus, the mere presence of another person in the field of view is not sufficient to compute where/what that person is looking at, which qualifies the claimed automaticity of such computations.

Emotions and perspective-taking are ubiquitous in our daily social interactions, but little is known about the relation between the two. This study examined whether and how emotions can influence even the most basic forms of perspective-taking. Experiment 1 showed that guilt made participants more other-centered in a simple visual perspective-taking task while anger tended to make them more self-centered. These two emotions had, however, no effect on the ability to handle conflicting perspectives. Since the guilt induction method used in Experiment 1 also induced feelings of self-incompetence and shame, Experiment 2 aimed at isolating the effects of these concomitant feelings. Self-incompetence/shame reduced participants' ability to handle conflicting perspectives but did not influence attention allocation. In sum, these results highlight that emotions can affect even the simplest form of perspective-taking and that such influence can be brought about by the modulation of different cognitive mechanisms.

International audience; The frequency-tagging approach has generally been confined to study low-level sensory processes and always found related activation over the occipital region. Here for the first time, we investigated with it, high-level socio-cognitive functions, i.e. the processing of what other people are looking at which is referred to as level 1 visual perspective taking (VPT). Sixteen participants were presented with visual scenes alternating at 2.5 Hz which were depicting a person and an object in a room, while recording electrophysiological brain activity. The person orientation and object position changed at every stimulus but the person in the room always faced the object, except on every fifth stimulus. We found responses in the electroencephalography (EEG) spectrum exactly at the frequency corresponding to the presentation of the scenes where the person could not see the object, i.e. 0.5 Hz. While the 2.5 Hz stimulation rate response focused on typical medial occipital sites, the specific 0.5 Hz response was found mainly over a centro-parietal region. Besides a robust group effect, these responses were significant and quantifiable for most individual participants. Overall, these observations reveal a clear measure of level 1-VPT representation, highlighting the potential of EEG frequency-tagging to capture high-level socio-cognitive functions in the brain.

Every day, we engage in social interactions with other people which require understanding their as well as our own mental states. Such capacity is commonly referred to as Theory of Mind (ToM). Disturbances of ToM are often reported in diverse pathologies which affect brain functioning and lead to problems in social interactions. Identifying ToM deficits is thus crucial to guide the clinicians in the establishment of adequate rehabilitation strategies for patients. Previous studies have demonstrated that ToM is not a unitary function yet currently there are very few standardized tests which allow identifying the type of cognitive processes affected when a patient exhibits a ToM deficit. In the current study, we present two belief reasoning tasks which have been used in previous research to disentangle two types of processes involved in belief reasoning: self-perspective inhibition and the spontaneous inference of another person’s belief. A three-step procedure was developed to provide clinicians with the tools to interpret the patients’ performances on the tasks. First, these tasks were standardized and normative data was collected on a sample of 124 healthy participants aged between 18 and 74. Data collected showed a decrease in performance as a function of age only in the task that loaded most in spontaneous other-perspective demands. There was however no effect of gender or educational level. Cut-off scores to identify deficits were then calculated for the different age groups separately. Secondly, the three-step procedure was applied to 21 brain-damaged patients and showed a large diversity of profiles, including selective deficits of the two targeted ToM processes. The diversity of profiles shows the importance to take into account the multiple facets of ToM during the diagnosis and rehabilitation of patients with suspected ToM deficits.

A growing body of evidence suggests that adults can monitor other people’s beliefs in an efficient way. However, the nature and the limits of efficient belief tracking are still being debated. The present study addressed these issues by testing (a) whether adults spontaneously process other people’s beliefs when overt task instructions assign priority to participants’ own belief, (b) whether this processing relies on low-level associative processes and (c) whether the propensity to track other people’s beliefs is linked to empathic disposition. Adult participants were asked to alternately judge an agent’s belief and their own belief. These beliefs were either consistent or inconsistent with each other. Furthermore, visual association between the agent and the object at which he was looking was either possible or impeded. Results showed interference from the agent’s belief when participants judged their own belief, even when low-level associations were impeded. This indicates that adults still process other people’s beliefs when priority is given to their own belief at the time of computation, and that this processing does not depend on low-level associative processes. Finally, performance on the belief task was associated with the Empathy Quotient and the Perspective Taking scale of the Interpersonal Reactivity Index, indicating that efficient belief processing is linked to a dispositional dimension of social functioning.

Processes for perspective-taking can be differentiated on whether or not they require us to mentally rotate ourselves into the position of the other person (Michelon & Zacks, 2006). Until now, only two perspective-taking tasks have been differentiated in this way, showing that judging whether something is to someone’s left or right does require mental rotation, but judging if someone can see something or not does not. These tasks differ firstly on whether the content of the perspective is visual or spatial and secondly on whether the type of the judgement is early-developing (level-1 type) or later-developing (level-2 type). Across two experiments, we tested which of these factors was likely to be most important by using four different perspective-taking tasks which crossed orthogonally the content of judgement (visual vs. spatial) and the type of judgement (level-1 type vs. level-2 type). We found that the level-2 type judgements, of how something looks to someone else and whether it is to their left or right, required egocentric mental rotation. On the other hand, level-1 type judgements, of whether something was in front of or behind someone and of whether someone could see something or not, did not involve mental rotation. We suggest from this that the initial processing strategies employed for perspective-taking are largely independent of whether judgements are visual or spatial in nature. Furthermore, early developing abilities have features that make mental rotation unnecessary.

Total sleep deprivation (TSD) is known to alter cognitive processes. Surprisingly little attention has been paid to its impact on social cognition. Here, we investigated whether TSD alters levels-1 and -2 visual perspective-taking abilities, i.e. the capacity to infer (a) what can be seen and (b) how it is seen from another person's visual perspective, respectively. Participants completed levels-1 and -2 visual perspective-taking tasks after a night of sleep and after a night of TSD. In these tasks, participants had to take their own (self trials) or someone else's (other trials) visual perspective in trials where both perspectives were either the same (consistent trials) or different (inconsistent trials). An instruction preceding each trial indicated the perspective to take (i.e. the relevant perspective). Results show that TSD globally deteriorates social performance. In the level-1 task, TSD affects the selection of relevant over irrelevant perspectives. In the level-2 task, the effect of TSD cannot be unequivocally explained. This implies that visual perspective taking should be viewed as partially state-dependent, rather than a wholly static trait-like characteristic., SCOPUS: ar.j, info:eu-repo/semantics/published

This study aimed to test whether individual differences in perspective taking could be explained with two underpinning cognitive dimensions: The ability to handle the conflict between our egocentric perspective and another person’s perspective and the relative attentional focus during processing on the egocentric perspective versus another person’s perspective. We conducted cluster analyses on 346 participants who completed a visual perspective-taking task assessing performance on these two cognitive dimensions. Individual differences were best reduced by forming four clusters, or profiles, of perspective-takers. This partition reflected a high heterogeneity along both dimensions. In addition, deconstructing the perspective-taking performance into two distinct cognitive dimensions better predicted participants’ self-reported everyday life perspective-taking tendencies. Altogether, considering attentional focus and conflict handling as two potential sources of variability allows forming a two-dimensional space that enriches our understanding of the individual differences in perspective taking.

In the paper a modification of a Socio-cognitive Particle Swarm Optimization algorithm, recently proposed by the authors, is presented. This modification consists in devising a mechanism for dynamic adaptation of the population structure of the swarm. Besides the design and rationale for the approach, referring to the state-of-the-art PSO original algorithm and several of its modifications, experimental results tackling popular benchmark functions are presented and discussed in detail., SCOPUS: cp.p, info:eu-repo/semantics/published

Keysar et al. (Keysar, Barr, Balin, & Brauner, 2000; Keysar, Lin, & Barr, 2003) report that adults frequently failed to use their conceptual competence for theory of mind (ToM) in an online communication game where they needed to take account of a speaker's perspective. The current research reports 3 experiments investigating the cognitive processes contributing to adults’ errors. In Experiments 1 and 2 the frequency of adults’ failure to use ToM was unaffected by perspective switching. In Experiment 3 adults made more errors when interpreting instructions according to the speaker's perspective than according to an arbitrary rule. We suggest that adults are efficient at switching perspectives, but that actually using what another person knows to interpret what they say is relatively inefficient, giving rise to egocentric errors during communication.

Objective: The validity and functional predictive values of the apraxia tests in the Birmingham Cognitive Screen (BCoS) were evaluated. BCoS was developed to identify patients with different forms of praxic deficit using procedures designed to be inclusive for patients with aphasia and/or spatial neglect. Method: Observational studies were conducted from a university neuropsychological assessment centre and from acute and rehabilitation stroke care hospitals throughout an English region. Volunteers from referred patients with chronic acquired brain injuries, a consecutive hospital sample of patients within 3 months of stroke (n=635) and a population based healthy control sample (n=100) were recruited. The main outcome measures used were the Barthel Index, the Nottingham Extended Activities of Daily Living Scale as well as recovery from apraxia. Results: There were high inter-rater reliabilities and correlations between the BCoS apraxia tasks and counterpart tests from the literature. The vast majority (88.3%) of the stroke survivors were able to complete the screen. Pantomime and gesture recognition tasks were more sensitive in differentiating between individuals with left hemisphere damage and right hemisphere damage whereas the Multistep Object Use test and the imitation task had higher functional correlates over and above effects of hemiplegia. Together, the initial scores of the four tasks enabled predictions with 75% accuracy, the recovery of apraxia and independence level at 9 months. Conclusions: As a model based assessment, BCoS offers a quick and valid way to detect apraxia and predict functional recovery. It enables early and informative assessment of most stroke patients for rehabilitation planning.

A standard view in the neuroscience literature is that the frontal lobes sustain our ability to process others' mental states such as beliefs, intentions and desires (this ability is often referred to as having 'theory of mind'). Here we report evidence from brain-damaged patients showing that, in addition to involvement of the frontal lobes, the left temporoparietal junction is necessary for reasoning about the beliefs of others.

Perspective taking is a crucial ability that guides our social interactions. In this study, we show how the specific patterns of errors of brain-damaged patients in perspective taking tasks can help us further understand the factors contributing to perspective taking abilities. Previous work [e.g., Samson, D., Apperly, I. A., Chiavarino, C., & Humphreys, G. W. (2004). Left temporoparietal junction is necessary for representing someone else's belief. Nature Neuroscience, 7, 499-500; Samson, D., Apperly, I. A., Kathirgamanathan, U., & Humphreys, G. W. (2005). Seeing it my way: A case of a selective deficit in inhibiting self-perspective. Brain, 128, 1102-1111] distinguished two components of perspective taking: the ability to inhibit our own perspective and the ability to infer someone else's perspective. We assessed these components using a new nonverbal false belief task which provided different response options to detect three types of response strategies that participants might be using: a complete and spared belief reasoning strategy, a reality-based response selection strategy in which participants respond from their own perspective, and a simplified mentalising strategy in which participants avoid responding from their own perspective but rely on inaccurate cues to infer the other person's belief. One patient, with a self-perspective inhibition deficit, almost always used the reality-based response strategy; in contrast, the other patient, with a deficit in taking other perspectives, tended to use the simplified mentalising strategy without necessarily transposing her own perspective. We discuss the extent to which the pattern of performance of both patients could relate to their executive function deficit and how it can inform us on the cognitive and neural components involved in belief reasoning. (c) 2007 Elsevier Ltd. All rights reserved.

In our recent research, we implemented an enhancement of Ant Colony Optimization incorporating the socio-cognitive dimension of perspective taking. Our initial results suggested that increasing the diversity of ant population — introducing different pheromones, different species and dedicated inter-species relations — yielded better results. In this paper, we explore the diversity issue by introducing novel diversity measurement strategies for ACO. Based on these strategies we compare both classic ACO and its socio-cognitive variation.

OBJECTIVE: We report data on the validation and functional correlates of Apples Test, which attempts to differentiate between different forms of unilateral neglect. METHOD: Study 1 presents data from 25 participants with chronic brain lesions who completed the Apples Test and another standard measure of neglect (Star Cancellation). The patients' performance relative to 86 controls was assessed and their relative performance across the two tests compared. Study 2 recruited 115 acute hospital stroke patients who completed the Apples Test as part of the Birmingham University Cognitive Screen procedure. We assessed the relations between the different forms of neglect. Study 3 examined neglect type (as measured by the Apples Test) among the acute stroke group in relation to their activities of daily living abilities and affect. RESULTS: In Study 1 Apples Test scores correlated with Star Cancellation performance, while also differentiating between neglect across the page and neglect of parts of objects. Study 2 confirmed the dissociation from Study 1. "Pure" forms of each type of neglect were equally prevalent after right and left hemisphere lesions, while the presence of both deficits was associated with right hemisphere damage. Study 3 showed that each form of neglect also correlated with other measures of cognition. When compared with pure page-based neglect, object-centered neglect was associated with a lower Barthel score (p < .001), while patients with both forms of neglect had higher level of depression (p < .001) than those with the pure forms. CONCLUSIONS: We conclude that the Apples test provides a clinically applicable measure of different forms of neglect. In addition it is a useful predictor of functional outcome. We discuss the nature of the two forms of neglect diagnosed by the test and the functional implications.

Previous research suggests that perspective-taking and other "theory of mind" processes may be cognitively demanding for adult participants, and may be disrupted by concurrent performance of a secondary task. In the current study, a Level-1 visual perspective task was administered to 32 adults using a dual-task paradigm in which the secondary task tapped executive function. Results suggested that the secondary task did not affect the calculation of perspective, but did affect the selection of the relevant (Self or Other) perspective for a given trial. This is the first direct evidence of a cognitively efficient process for "theory of mind" in adults that operates independently of executive function. The contrast between this and previous findings points to a distinction between simple perspective-taking and the more complex and cognitively demanding abilities more typically examined in studies of "theory of mind". It is suggested that these findings may provide a parsimonious explanation of the success of infants on 'indirect' measures of perspective-taking that do not explicitly require selection of the relevant perspective.

In a series of three visual perspective-taking experiments, we asked adult participants to judge their own or someone else's visual perspective in situations where both perspectives were either the same or different. We found that participants could not easily ignore what someone else saw when making self-perspective judgments. This was observed even when participants were only required to take their own perspective within the same block of trials (Experiment 2) or even within the entire experiment (Experiment 3), i.e. under conditions which gave participants a clear opportunity to adopt a strategy of ignoring the other person's irrelevant perspective. Under some circumstances, participants were also more efficient at judging the other person's perspective than at judging their own perspective. Collectively, these results suggest that adults make use of rapid and efficient processes to compute what other people can see.

When trying to make sense of other people's behaviour we usually invoke their mental states, such as their intentions, beliefs or emotions. This mind reading ability has been traditionally investigated in developmental psychology and comparative psychology but is now receiving increasing attention from the cognitive neurosciences. I will show the important role that neuropsychology plays in unravelling the cognitive and neural basis of our mind reading abilities. I will illustrate this by showing how cases of adults with acquired brain lesions can help us tease apart the different mechanisms that underlie mind reading abilities and can help us understand the nature of these mechanisms, especially their relation to language and executive function.

Much of what we know about other people's beliefs comes non-inferentially from what people tell us. Developmental research suggests that 3-year-olds have difficulty processing such information: they suffer interference from their own knowledge of reality when told about someone's false belief (e.g., [Wellman, H. M., & Bartsch, K. (1988). Young children's reasoning about beliefs. Cognition, 30, 239-277.]). The current studies examined for the first time whether similar interference occurs in adult participants. In two experiments participants read sentences describing the real colour of an object and a man's false belief about the colour of the object, then judged the accuracy of a picture probe depicting either reality or the man's belief. Processing costs for picture probes depicting reality were consistently greater in this false belief condition than in a matched control condition in which the sentences described the real colour of one object and a man's unrelated belief about the colour of another object. A similar pattern was observed for picture probes depicting the man's belief in most cases. Processing costs were not sensitive to the time available for encoding the information presented in the sentences: costs were observed when participants read the sentences at their own pace (Experiment 1) or at a faster or a slower pace (Experiment 2). This suggests that adults' difficulty was not with encoding information about reality and a conflicting false belief, but with holding this information in mind and using it to inform a subsequent judgement. (C) 2007 Elsevier B.V. All rights reserved.

We incorporate socio-cognitively inspired metaheuristics, which we have used successfully in the ACO algorithms in our past research, into the classical particle swarm optimization algorithms. The swarm is divided into species and the particles get inspired not only by the global and local optima, but share their knowledge of the optima with neighboring agents belonging to other species. Our experimental research gathered for common benchmark functions tackled in 100 dimensions show that the metaheuristics are effective and perform better than the classic PSO. We experimented with various proportions of different species in the swarm population to find the best mix of population., SCOPUS: cp.p, info:eu-repo/semantics/published

Efficient social interactions require taking into account other people’s mental states such as their beliefs, intentions or emotions. Recent studies have shown that in some social situations at least, we do spontaneously take into account others’ mental states. The extent to which we have dedicated brain areas for such spontaneous perspective taking is however still unclear. Here, we report two brain-damaged patients whose common lesions were almost exclusively in the left posterior temporoparietal junction (TPJp) and who both showed the same striking and distinctive theory of mind (ToM) deficit. More specifically, they had an inability to take into account someone else’s belief unless they were explicitly instructed to tell what that other person thinks or what that person will do. These patients offer a unique insight into the causal link between a specific subregion of the TPJ and a specific cognitive facet of ToM.

A growing body of work suggests that in some circumstances, humans may be capable of ascribing mental states to others in a way that is fast, cognitively efficient, and implicit (implicit mentalizing hypothesis). However, the interpretation of this work has recently been challenged by suggesting that the observed effects may reflect "submentalizing" effects of attention and memory, with no ascription of mental states (submentalizing hypothesis). The present study employed a strong test between these hypotheses by examining whether apparently automatic processing of another's visual perspective is influenced by experience-dependent beliefs about whether that person can see. Altercentric interference was observed when participants judged their own perspective on stimuli involving an avatar wearing goggles that participants believed to be transparent but not when they believed the goggles to be opaque. These results are consistent with participants ascribing mental states to the avatar and not with the submentalizing hypothesis that altercentric interference arises merely because avatars cue shifts in spatial attention. (PsycINFO Database Record

Objective: We examined the utility of the Birmingham Cognitive Screen (BCoS) in discriminating cognitive profiles and recovery of function across stroke survivors. BCoS was designed for stroke-specific problems across 5 cognitive domains: (a) controlled and spatial attention, (b) language, (c) memory, (d) number processing, and (e) praxis. Method: On the basis of specific inclusion criteria, this cross-section observational study analyzed cognitive profiles of 657 subacute stroke patients, 331 of them reassessed at 9 months. Impairments on 32 measures were evaluated by comparison with 100 matched healthy controls. Measures of affect, apathy, and activities of daily living were also taken. Between-subjects group comparisons of mean performance scores and impairment rates and within-subject examination of impairment rates over time were conducted. Logistic regressions and general linear modeling were used for multivariate analysis of domain-level effects on outcomes. Results: Individuals with repeated stroke experienced significantly less cognitive recovery at 9 months than those with a first stroke despite similar initial level of cognitive performance. Individuals with left hemisphere lesions performed more poorly than those with right hemisphere lesions, but both groups showed similar extent of recovery at 9 months. BCoS also revealed lesion-side-specific deficits and common areas of persistent problems. Functional outcome at 9 months correlated with domain-level deficits in controlled attention, spatial attention, and praxis over and above initial dependency and concurrent levels of affect and apathy. Conclusion: The study demonstrates how BCoS can identify differential cognitive profiles across patient groups. This can potentially help predict outcomes and inform rehabilitation. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

The retention of first-order theory of mind (ToM) despite severe loss of grammar has been reported in two patients with left hemisphere brain damage (Varley and Siegal, 2000; Varley, Siegal, and Want, 2001). We report a third, and more detailed, case study. Patient PH shows significant general language impairment, and severe grammatical impairment similar to that reported in previous studies. In addition we were able to show that PH's impairment extends to grammatical constructions most closely related to ToM in studies of children (embedded complement clauses and relative clauses). Despite this, PH performed almost perfectly on first-order false belief tasks and on a novel nonverbal second-order false belief task. PH was also successful on a novel test of "ToM semantics" that required evaluation of the certainty implied by different mental state terms. The data strongly suggest that grammar is not a necessary source of structure for explicit ToM reasoning in adults, but do not rule out a critical role for "ToM semantics." In turn this suggests that the relationship observed between grammar and ToM in studies of children is the result of an exclusively developmental process.

Precedence of the global over the local level in visual perception is well established by the use of compound, or hierarchical, stimuli. However, (a) virtually nothing is known concerning the fate of global precedence with normal aging, and (b) there is still a debate about the early versus late perceptual locus of the effect. The present study was planned to investigate both topics. Two experiments are reported where young adult and elderly subjects were enrolled for the recognition of compound letters either at the global or at the local level. In order to recruit late perceptual processes, the case of the letters varied in such a way that subjects had to activate graphemic codes to take their decision. It appeared that the global precedence effect was preserved. This observation shows an early perceptual source of the global precedence effect, which is then transferred to later stages of information processing. Age did not affect the global precedence phenomenon.

We present an application of Ant Colony Optimisation (ACO) to simulate socio-cognitive features of a population. We incorporated perspective taking ability to generate three different proportions of ant colonies: Control Sample, High Altercentricity Sample, and Low Alter-centricity Sample. We simulated their performances on the Travelling Salesman Problem and compared them with the classic ACO. Results show that all three ‘cognitively enabled’ ant colonies require less time than the classic ACO. Also, though the best solution is found by the classic ACO, the Control Sample finds almost as good a solution but much faster. This study is offered as an example to illustrate an easy way of defining inter-individual interactions based on stigmergic features of the environment.

The neurohormone Oxytocin (OT) has been one of the most studied peptides in behavioral sciences over the past two decades. Many studies have suggested that OT could increase trusting behaviors. A previous study, based on the “Envelope Task” paradigm, where trust is assessed by the degree of openness of an envelope containing participant’s confidential information, showed that OT increases trusting behavior and reported one of the most powerful effects of OT on a behavioral variable. In this paper we present two failed replications of this effect, despite sufficient power to replicate the original large effect. The non-significant results of these two failed replications clearly exclude a large effect of OT on trust in this paradigm but are compatible with either a null effect of OT on trust, or a small effect, undetectable with small sample size (N = 95 and 61 in Study 1 and 2, respectively). Taken together, our results question the purported size of OT’s effect on trust and emphasize the need for replications.

Background Previous studies have shown that alcohol-dependent (AD) individuals have difficulties inferring other people's emotion, understanding humor, and detecting a faux pas. This study aimed at further understanding the nature of such “Theory of Mind” (ToM) difficulties. Methods A total of 34 recently detoxified AD and 34 paired controls were compared based on 2 nonverbal and video-based false belief tasks. These tasks were designed to identify 3 different types of deficits: (i) a deficit in dealing with the general task demands, (ii) a selective deficit in self-perspective inhibition, and (iii) a deficit in tracking the other person's mental state. (i) and (ii) are compatible with the hypothesis of a prefrontal cortex dysfunction being at the origin of AD individuals’ social difficulties, while (iii) would suggest the possible contribution of a dysfunction of the temporo-parietal junction in explaining the social difficulties. Results Group analyses highlighted that AD individuals performed worse on the 2 false belief tasks than controls. Individual analyses showed, however, that just under half of the AD individuals were impaired compared to controls. Moreover, most of the AD individuals who were impaired showed a deficit in tracking the other person's belief. This deficit was linked to disease-related factors such as illness duration, average alcohol consumption, and craving but not to general reasoning abilities, depression, anxiety, or demographic variables. Conclusions Just under half of the AD individuals tested showed a ToM deficit, and in most cases, the deficit concerned the tracking of other people's mental states. Such a type of deficit has previously been associated with lesions to the temporo-parietal brain areas, indicating that a prefrontal cortex dysfunction may not be the sole origin of the social cognition deficits observed in alcohol dependence.

Calculating prodigies are individuals who are exceptional at quickly and accurately solving complex mental calculations. With positron emission tomography (PET), we investigated the neural bases of the cognitive abilities of an expert calculator and a group of non-experts, contrasting complex mental calculation to memory retrieval of arithmetic facts. We demonstrated that calculation expertise was not due to increased activity of processes that exist in non-experts; rather, the expert and the non-experts used different brain areas for calculation. We found that the expert could switch between short-term effort-requiring storage strategies and highly efficient episodic memory encoding and retrieval, a process that was sustained by right prefrontal and medial temporal areas.

We describe the performance of a brain-damaged subject who suffered from visual agnosia leading to major difficulties in generating and exploiting visual representations from long-term memory. His performance in a physical judgement task in which he was required to answer questions about the visual shapes of Arabic numerals reflected his agnosic problems. However, he showed no impairment in usual number processing and calculation tasks. This case shows that, despite some commonalities in number and object processing, actual numerical processes are not affected by visual agnosia and can be preserved even when fine visual processes are impaired.

We describe the basic and exceptional calculation abilities of a calculating prodigy whose performances were investigated in single- and multi-digit number multiplication, numerical comparison, raising of powers, and short-term memory tasks. The study shows how the highly efficient long-term memory storage and retrieval processes of this calculating prodigy, his knowledge of calculation algorithms, and his good short-term memory capacity all contribute to his calculation expertise. Moreover, his pattern of performance in tasks based on memory retrieval strategies sheds new light on the problem-size/difficulty effect exhibited by normal subjects in basic arithmetical operations. When direct memory retrieval is the only strategy used by this calculating prodigy to answer a problem, the size of the item and the size of the answer do not affect the response latency. This result supports interpretations of the problem-size/difficulty effect in terms of learning and practice, and challenges interpretations in terms of magnitude itself.

We report a single case study of a 22-year-old, brain-damaged patient, Jennifer, who showed a semantic deficit affecting living entities (animals and fruit and vegetables) to a greater extent than non-living ones (implements and means of transport). We first show that this category effect was reliable both across time and naming conditions and that it was not an artefact of uncontrolled stimulus factors. We then show that Jennifer had no impairment at the visual or structural processing level and that her deficit was probably located at a semantic processing level. Specific semantic deficits for living entities have usually been explained by damage to the visual semantic system. However, when Jennifer's access to visual and non-visual semantics was assessed through an attribute-verification task, no evidence of an attribute-specific impairment was found: Jennifer was equally impaired in retrieving visual and non-visual attributes of living entities and she was not at all impaired in retrieving visual attributes of non-living entities. Thus, the hypothesis of damage to visual semantics cannot account for the pattern of living things impairment found in this patient. Rather, this pattern seems to require the assumption that the semantic system is organized according to the living/non-living dimension.

To test different hypotheses about age-related slowing of word and picture naming, response latencies of young and older adults were compared in 2 experiments using the same 4 tasks: picture naming, written word pronunciation, and picture and word categorization. In each case, the target word or picture was presented with a distractor word that had to be ignored. Analyses showed the expected main effects of age, modality, and interference conditions but no consistent interaction between age and other factors. More particularly, age-related slowing was similar in word and picture processing and interference was proportional to overall speed of responding. Thus, no support was found for the hypotheses assuming either declining inhibitory mechanisms or task-specific deficits in older adults. These results were discussed in relation to characteristics of the experimental tasks.