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.

Narcissism is a prevalent personality trait associated with low concern for others and high self-focus. Congruently, reduced automatic imitation in narcissists was reported in one study (23 participants), but it was not replicated in another (57 participants). In this study, 100 participants completed the previously used narcissism and automatic imitation measures but here along with a visual perspective-taking task allowing to dissociate 4 profiles of perspective-takers. While we confirmed a non-replication at whole-sample level, we did find a reliable negative association between narcissism and automatic imitation among egocentric perspective-takers, that is, characterized as highly self-centered when tasked to adopt someone else's point of view. Our findings shed a new light on whether narcissistic individuals are less sensitive to others, highlight the importance of considering performance-based individual differences within the narcissistic personality, and revisit the recent claim that automatic imitation poorly relates to social functioning by presenting a theoretical framework that questions the sensitivity of the automatic imitation task.

Scientific evidence indicating that humans are tuned to rapidly notice and respond to others’ behaviors mainly stem from the laboratory observations that we spontaneously imitate others’ movements even when such imitation interferes with a task at hand. For instance, seeing another person’s index finger being lifted slows us down when tasked to lift a non-index finger. One study showed however that highly narcissistic individuals are less interfered by their tendency to imitate others, but then this was not observed in two other studies. The current study shows that highly narcissistic individuals are indeed less interfered by their spontaneous imitations but only within a fraction of the population that is characterized as highly self-centered when tasked to adopt someone else’s point of view.

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.

A metaheuristic proposed by us recently, Ant Colony Optimization (ACO) hybridized with socio-cognitive inspirations, turned out to generate interesting results when compared to classic ACO. Even though it does not always find better solutions to the considered problems, it usually finds sub-optimal solutions. Moreover, instead of a trial-and-error approach to configure the parameters of the ant species in the population, the actual structure of the population emerges from a predefined species-to-species ant migration strategies in our approach. Experimental results of our approach are compared to classic ACO and selected socio-cognitive versions of this algorithm.

Moral judgements are crucial for social life and rely on the analysis of the agent’s intention and the outcome of the agent’s action. The current study examines to the influence of how the information is presented on moral judgement. The first experiment investigated the effects of the order in which intention and outcome information was presented. The results showed that participants relied more on the last presented information, suggesting a recency effect. The second experiment required participants to make two types of judgments (wrongness vs. punishment) and manipulated the order of the requested two types of judgments. Results showed an asymmetrical transfer effect whereby punishment judgements, but not wrongness judgements were affected by the order of presentation. This asymmetrical transfer effect was likely linked to the ambiguity of the punishment judgement. Altogether, the study showed that the order in which information was presented and the order in which one was asked to think about the wrongness of an action or the punishment that the action deserves were two factors that should be irrelevant, but actually influenced moral judgements. The influence of these factors was mostly observed during the most difficult judgements, precisely in situations where human decision is called upon, such as in court trials.

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.

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.

Recently we proposed an application of ant colony optimization (ACO) to simulate socio-cognitive features of a population, incorporating perspective-taking ability to generate differently acting ant colonies. Although our main goal was simulation, we took advantage of the fact that the quality of the constructed system was evaluated based on selected traveling salesman problem instances, and the resulting computing system became a metaheuristic, which turned out to be a promising method for solving discrete problems. In this paper, we extend the initial sets of populations driven by different perspective-taking inspirations, seeking both optimal configuration for solving a number of TSP benchmarks, at the same time constituting a tool for analyzing socio-cognitive features of the individuals involved. The proposed algorithms are compared against classic ACO, and are found to prevail in most of the benchmark functions tested.

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.

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.

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.

Neuropsychological assessments have typically divided cognitive functions into several domains (eg, attention, language, memory; Heilman & Valenstein, 2012), and this division of cognition into different domains is supported by evidence from functional brain imaging in normal participants, where brain activity clusters into different domains for language, memory, attention, and so forth (Laird et al., 2011). Previous studies have shown that the co-occurrence of impairments in two or more domain functions, such as impaired executive functions or sustained attention alongside language impairments or neglect, may adversely affect the rehabilitation outcome of the primary function–that is, in language (Lambon Ralph, Snell, Fillingham, Conroy, & Sage, 2010) or visual attention (Malhotra et al., 2005; Robertson, 2001). Therefore, assessment needs to cover not only primary symptoms but also contributing, co-occurring impairments.

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.

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.

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.

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.