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Something to talk about: Are conversation sizes constrained by mental modeling abilities?

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Abstract

Conversations are ubiquitous and central elements of daily life. Yet a fundamental feature of conversation remains a mystery: It is genuinely difficult to maintain an everyday conversation with more than four speakers. Why? We introduce a “mentalizing explanation” for the conversation size constraint, which suggests that humans have a natural limit on their ability to model the minds of others, and that this limit, in turn, shapes the sizes of everyday conversations. Using established methodologies for investigating conversation size, we pit this mentalizing hypothesis against two competing explanations—that the size of a conversation is limited by a short-term memory capacity (limiting the factual information we process) or by an auditory constraint (speakers need to be able to hear what each other are saying)—in conversations drawn from a real-world college campus and from Shakespearean plays. Our results provide support for the mentalizing hypothesis and also render alternative accounts less plausible.

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... Yet, in the augmentation of face-to-face interactions, current systems are often positioned for one-on-one use [22,28] or a small number of users [32]. While everyday conversations at social events commonly involve only about four speakers [30], people engaging in these conversations, as demonstrated in prior literature [32], move between conversations, leaving and creating new groups. Whilst the conversations are often within small groups, these groups interchange through a larger pool [30] as users browse the crowd [31,32]. ...
... While everyday conversations at social events commonly involve only about four speakers [30], people engaging in these conversations, as demonstrated in prior literature [32], move between conversations, leaving and creating new groups. Whilst the conversations are often within small groups, these groups interchange through a larger pool [30] as users browse the crowd [31,32]. This pattern is not reflected in prior investigations of one-on-one multiple-user technology instances. ...
... The study ran for 65 minutes, which came to 35 minutes after the last person entered. This gave all participants enough time to settle into the study, per prior research guidelines [30]. One key benefit of the method we chose is that it enabled participants to enter the study room when they felt ready and were able to use the device as in normal contexts, all without disclosing potentially confounding information before the subject entered the room. ...
Article
Full-text available
Technologies that augment face-to-face interactions with a digital sense of self have been used to support conversations. That work has employed one homogenous technology, either 'off-the-shelf' or with a bespoke prototype, across all participants. Beyond speculative instances, it is unclear what technology individuals themselves would choose, if any, to augment their social interactions; what influence it may exert; or how use of heterogeneous devices may affect the value of this augmentation. This is important, as the devices that we use directly affect our behaviour, influencing affordances and how we engage in social interactions. Through a study of 28 participants, we compared head-mounted display, smartphones, and smartwatches to support digital augmentation of self during face-to-face interactions within a group. We identified a preference among participants for head-mounted displays to support privacy, while smartwatches and smartphones better supported conversational events (such as grounding and repair), along with group use through screen-sharing. Accordingly, we present software and hardware design recommendations and user interface guidelines for integrating a digital form of self into face-to-face conversations.
... Yet, in the augmentation of face-to-face interactions, current systems are often positioned for one-on-one use [22,28] or a small number of users [32]. While everyday conversations at social events commonly involve only about four speakers [30], people engaging in these conversations, as demonstrated in prior literature [32], move between conversations, leaving and creating new groups. Whilst the conversations are often within small groups, these groups interchange through a larger pool [30] as users browse the crowd [31,32]. ...
... While everyday conversations at social events commonly involve only about four speakers [30], people engaging in these conversations, as demonstrated in prior literature [32], move between conversations, leaving and creating new groups. Whilst the conversations are often within small groups, these groups interchange through a larger pool [30] as users browse the crowd [31,32]. This pattern is not reflected in prior investigations of one-on-one multiple-user technology instances. ...
... The study ran for 65 minutes, which came to 35 minutes after the last person entered. This gave all participants enough time to settle into the study, per prior research guidelines [30]. One key benefit of the method we chose is that it enabled participants to enter the study room when they felt ready and were able to use the device as in normal contexts, all without disclosing potentially confounding information before the subject entered the room. ...
Conference Paper
Technologies that augment face-to-face interactions with a digital sense of self have been used to support conversations. That work has employed one homogenous technology, either 'off-the-shelf' or with a bespoke prototype, across all participants. Beyond speculative instances, it is unclear what technology individuals themselves would choose, if any, to augment their social interactions; what influence it may exert; or how use of heterogeneous devices may affect the value of this augmentation. This is important, as the devices that we use directly affect our behaviour, influencing affordances and how we engage in social interactions. Through a study of 28 participants, we compared head-mounted display, smartphones, and smartwatches to support digital augmentation of self during face-to-face interactions within a group. We identified a preference among participants for head-mounted displays to support privacy, while smartwatches and smartphones better supported conversational events (such as grounding and repair), along with group use through screen-sharing. Accordingly, we present software and hardware design recommendations and user interface guidelines for integrating a digital form of self into face-to-face conversations.
... There appear to be upper limits to broadcast group size in the human group bonding behaviors studied thus far. The number of individuals who typically converse (Dezecache & Dunbar, 2012;Dunbar, 2016b;Dunbar, Duncan, & Nettle, 1995;Krems, Dunbar, & Neuberg, 2016) and laugh (Dezecache & Dunbar, 2012) together seems limited to approximately four. These restrictions appear to be based on limits in mentalizing ability (the ability to process others' mental states). ...
... Keeping track of more than four minds may simply be too cognitively demanding to do for very long. Indeed, Krems et al. (2016) conducted a discriminatory hypothesis test, in which they pit three potential explanations for observed limits to conversation group size against one another-auditory constraints (conversationalists need to be able to hear one another), short-term memory capacity, and mentalizing ability. Using field observation techniques, Krems et al. (2016) counted the size of conversation groups and then approached these groups to interview them on the topic of their conversation. ...
... Indeed, Krems et al. (2016) conducted a discriminatory hypothesis test, in which they pit three potential explanations for observed limits to conversation group size against one another-auditory constraints (conversationalists need to be able to hear one another), short-term memory capacity, and mentalizing ability. Using field observation techniques, Krems et al. (2016) counted the size of conversation groups and then approached these groups to interview them on the topic of their conversation. They classed these conversations into one of three categories: (i) conversations involving the mental states of absent parties, (ii) conversations involving non-mentalizing facts about absent parties, and (iii) conversations not involving reference to absent parties. ...
... At that event, it is likely that you enjoyed far more two-, three-, and four-person conversations than five-or six-person conversations. Conversations typically fission when they grow to contain five or more speakers (Krems, Dunbar, & Neuberg, 2016). This conversation size constraint has been colloquially termed 'the dinner party problem'-referring to the genuine difficulty of maintaining a casual, freely-forming conversation (as opposed to a lecture or formal) discussion with more than four speakers. ...
... This conversation size constraint has been colloquially termed 'the dinner party problem'-referring to the genuine difficulty of maintaining a casual, freely-forming conversation (as opposed to a lecture or formal) discussion with more than four speakers. Whereas existing research has both demonstrated this constraint across a range of social contexts (Dezecache & Dunbar, 2012;Dunbar et al., 1995;Krems & Dunbar, 2013;Matthews & Barrett, 2005;Stiller et al., 2003), and has also explained why this four-person constraint might exist (Cohen, 1971;Dunbar, et al., 1995;Krems et al., 2016;Sommer, 1971;Webster, 1965), little research has focused on asking why four, specifically, seems to be a magic number in human sociality. Just what is so special about four? ...
... Everyday, casual conversations-as opposed to lectures or formal discussions-rarely exceed four participants (Dezecache & Dunbar, 2013;Dunbar, Duncan & Nettle, 1995;Dunbar, 2009;Dunbar, 2016;Krems et al., 2016). For example, Krems et al.'s (2016) recent observation of freely-forming conversation groups (i.e., consisting of individuals speaking and those paying close attention to the speaker[s]) on a university campus found that typical conversations had an average upper limit of about four speakers. ...
Article
It is genuinely difficult to sustain a casual conversation that includes more than four speakers. Add a fifth speaker, and the conversation often quickly fissions into smaller groups. Termed ‘the dinner party problem,’ this four-person conversation size limit is believed to be caused by evolved cognitive constraints on human mentalizing capacities. In this view, people can mentally manage three other minds at any one time, leading to four-person conversations. But whereas existing work has posited and empirically tested alternative accounts of what drives the conversation size constraint, to our knowledge, no work has explored the question of why this capacity is specifically four? In this theoretical paper, we (a) review research demonstrating this cognitive constraint in sociality, (b) review the relevant working memory literature, which has explored the “why four” question at some length, and (c) we begin to pose possible answers to our specific social “why four” question. Using simple mathematical models of small-scale sociality, which we imbue with evolutionarily-relevant content, we present one novel possible explanation for the four-person conversation size constraint.
... Yet, in the augmentation of face-to-face interactions, current systems are often positioned for one-on-one use [22,28] or a small number of users [32]. While everyday conversations at social events commonly involve only about four speakers [30], people engaging in these conversations, as demonstrated in prior literature [32], move between conversations, leaving and creating new groups. Whilst the conversations are often within small groups, these groups interchange through a larger pool [30] as users browse the crowd [31,32]. ...
... While everyday conversations at social events commonly involve only about four speakers [30], people engaging in these conversations, as demonstrated in prior literature [32], move between conversations, leaving and creating new groups. Whilst the conversations are often within small groups, these groups interchange through a larger pool [30] as users browse the crowd [31,32]. This pattern is not reflected in prior investigations of one-on-one multiple-user technology instances. ...
... The study ran for 65 minutes, which came to 35 minutes after the last person entered. This gave all participants enough time to settle into the study, per prior research guidelines [30]. One key benefit of the method we chose is that it enabled participants to enter the study room when they felt ready and were able to use the device as in normal contexts, all without disclosing potentially confounding information before the subject entered the room. ...
Preprint
Full-text available
Technologies that augment face-to-face interactions with a digital sense of self have been used to support conversations. That work has employed one homogenous technology, either 'off-the-shelf' or with a bespoke prototype, across all participants. Beyond speculative instances, it is unclear what technology individuals themselves would choose, if any, to augment their social interactions; what influence it may exert; or how use of heterogeneous devices may affect the value of this augmentation. This is important, as the devices that we use directly affect our behaviour, influencing affordances and how we engage in social interactions. Through a study of 28 participants, we compared head-mounted display, smartphones, and smartwatches to support digital augmentation of self during face-to-face interactions within a group. We identified a preference among participants for head-mounted displays to support privacy, while smartwatches and smartphones better supported conversational events (such as grounding and repair), along with group use through screen-sharing. Accordingly, we present software and hardware design recommendations and user interface guidelines for integrating a digital form of self into face-to-face conversations.
... Indeed, while most attention has historically been drawn to the study of child language acquisition, more recent studies have pointed to a significant gap in our understanding of the relation between language and adult higher-order intentionality. Moreover, several primatologists and evolutionary psychologists have recently argued the adult capacity for higher-order intentionality may have been critical for the emergence of many uniquely human behaviors and cultural institutions including communication, humor, religion, cooperation, story-telling, and even consciousness (Corballis, 2011;Dunbar, 2003Dunbar, , 2005Dunbar, , 2008Dunbar, Launay, & Curry, 2016;Graziano, 2013;Krems, Dunbar, & Neuberg, 2016;Tomasello, 2008). Indeed, both ancient and modern humans have long occupied a social ecological niche in which the ability to monitor and manage social interactions, reason about other's motives and intentions, keep track of relationships, and decide who can be trusted has been of critical importance (Byrne & Whiten, 1989;Dunbar, 2003;Humphrey, 1976). ...
... 117e137;Tomasello, 2008), a capacity which non-human primates are unable to duplicate (Call & Tomasello, 2008). Further, observational studies have also shown that within typical freely-forming natural conversations, fourth or fifth-order mentalising is relatively common, especially given that many conversations are not strictly dyadic: around half of conversations contain three or more persons (Dunbar, Duncan, & Nettle, 1995) or refer to absent third-party individuals (Dunbar, Duncan, & Marriott, 1997;Krems et al., 2016). In principle, intentional states therefore provide a natural platform for communication through mentalising capacity (an individual's understanding of states of mind, typically exemplified by the use of words like believe, intend, suppose, think, et cetera). ...
Article
Theory of mind, also known as mentalising, meta-representation, second-order intentionality, or mindreading is the ability to attribute and reflect on the mental states of others. A number of investigators have noted that an important relationship exists between child language development and children’s understanding of second-order intentionality. However, although the ontogeny of theory of mind has been extensively studied over the past few decades, only recently have we begun to understand more concerning the limits of human mentalising ability in adults. For example, several studies have shown that the limits of mentalising ability for normal adults are consistently placed around fifth-order intentionality (i.e. I believe that you suppose that I imagine that you want me to believe that...), forming a naturally recursive hierarchy which corresponds to increasingly embedded mindreading. Moreover, several psychologists have recently suggested the adult capacity for higher-order intentionality may have played a critical role in the evolution of language, including especially the ability for recursive syntax comprehension and production, according to a cognitive bootstrapping effect. Here, we used the Imposing Memory Task (n = 210 female and 204 male adults) to analyse the association and interaction between higher-order intentionality capacity and performance on a recursive syntax measure. Multiple regression analyses indicated that recursive syntax abilities are lower than mindreading competences below fifth-order, but then reverses at higher values. In addition, a path analysis further suggested intentionality capacity as the likely causal variable. Thus, these results seem to suggest that first-order through fifth-order intentionality is necessary to assist the processing of simpler syntactic structures, but beyond fifth-order intentionality the cognitive scaffolding provided by recursive syntax may be engaged to enable higher-order mentalising. In summary, this may explain in part how and why many modern languages exhibit recursive syntax. *Now available for free download for a limited time: www.sciencedirect.com/science/article/pii/S091160441630029X
... Similarly, the dyad proved to be the most common group size at observations during free play at a nursery school, tourist parties visiting a national monument, and the size of dinner parties in a restaurant or conversation lounge [16,17]. More recently, a program of research by Dunbar and colleagues [18][19][20][21] has found support for Cohen's [16] hypothesis that, for conversation groups specifically, there is an upper limit of four persons who can engage in active conversation, primarily due to cognitive constraints. It also seems plausible that conversations can be coordinated (e.g., turn-taking, being able to hear one another well) better within a group of up to four persons rather than groups much larger in size. ...
... These results are in line with classic research conducted in the 1950s and 1970s [14][15][16][17] which also found dyads to be the most common group size at local sites with local participants (also see recent work by Dunbar and colleagues for conversation sizes specifically, [18][19][20][21]). Yet how do dyads relate to other, larger, group sizes? ...
Article
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A salient objective feature of the social environment in which people find themselves is group size. Knowledge of group size is highly relevant to behavioural scientists given that humans spend considerable time in social settings and the number of others influences much of human behaviour. What size of group do people actually look for and encounter in everyday life? Here we report four survey studies and one experience-sampling study (total N = 4,398) which provide evidence for the predominance of the dyad in daily life. Relative to larger group sizes, dyads are most common across a wide range of activities (e.g., conversations, projects, holidays, movies, sports, bars) obtained from three time moments (past activities, present, and future activities), sampling both mixed-sex and same-sex groups, with three different methodological approaches (retrospective reports, real-time data capture, and preference measures) in the United States and the Netherlands. We offer four mechanisms that may help explain this finding: reciprocity , coordination , social exclusion , and reproduction . The present findings advance our understanding of how individuals organize themselves in everyday life.
... The mean number of people involved in a conversation was 4.6 ± 2.3 SD. This is a little higher than, but well within the range of, that reported by previous studies (Dezecache and Dunbar 2012;Dunbar 2016;Dunbar et al. 1995;Krems et al. 2016). Figure 2 partitions conversation group size by the composition of the group. ...
... The values for mean conversation group size are all well within the range of variation in conversation group size observed in previous samples of European and American populations (Dezecache and Dunbar 2012;Dunbar 2016;Dunbar et al. 1995;Krems et al. 2016). Although the proportion of time devoted to social topics in the present sample (76%) is slightly higher than in previous European samples (66-70%: Dunbar et al. 1997;Emler 1994), it is clearly in broadly the same ballpark: natural conversations are overwhelmingly dominated by social topics. ...
Article
Previous empirical studies have suggested that language is primarily used to exchange social information, but our evidence on this derives mainly from English speakers. We present data from a study of natural conversations among Farsi (Persian) speakers in Iran and show that not only are conversation groups the same size as those observed in Europe and North America, but people also talk predominantly about social topics. We argue that these results reinforce the suggestion that language most likely evolved for the transmission of information about the social world. We also explore sex differences in conversational behavior: while the pattern is broadly similar between the sexes, men may be more sensitive than women are to discussing some topics in the presence of many other people.
... One reason for this may be that, as group size increases, it becomes increasingly difficult for listeners to hear and understand multiple speakers (Argyle, Lalljee, & Cook, 1968;Cohen, 1971;Leavitt & Mueller, 1955). For this reason, freely forming conversation groups only very rarely exceed four individuals (one speaker and three listeners; Dahmardeh & Dunbar, 2018;Dezecache & Dunbar, 2012;Dunbar et al., 1995;Dunbar, 2016;Krems, Dunbar, & Neuberg, 2016;Waller et al., 2011). In contrast, gesture appears not to suffer the same limitations from noise interference as auditory communication, as larger groups gestured proportionately more frequently. ...
... In fact, sample size is usually a problem only in so far as statistical tests are more conservative when samples are small. Moreover, consistent with the way in which small and large groups have traditionally been defined in previous studies (Dahmardeh & Dunbar, 2018;Dezecache & Dunbar, 2012;Dunbar, 2016;Dunbar et al., 1995;Krems et al., 2016;Waller et al., 2011), the fact that we find consistent statistical differences between our small and large groups suggests that the small and large groups measured here represent actual group size categories of real consequence and that the results are robust. ...
Article
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Exploitation of food resources that are dispersed in time and space has been crucial to the evolutionary success of humans. Recent experimental work has shown that an absence of communication impairs decision‐making in a foraging task. Here, we found that individuals in larger teams were more likely to reach group consensus and were more accurate and efficient foragers. Individuals in larger teams were also more likely to gesture to one another, while levels of verbal exchange were not significantly different in small and large groups. At last, teams in which individuals reported that they knew one another and rated team members as helpful and information‐seeking were more accurate in their foraging. Overall, our findings offer experimental evidence that larger, communicating, familiar teams are quicker and more accurate foragers. We therefore suggest that complex communication within socially bonded relationships may have been important to the ecological success of the human lineage.
... p < 0.001) and pub type (F 1,91 = 8.55, p = 0.004), but not for sex (F 1,91 = 0.03, p = 0.855). Note that those attending their 'local' and those in community pubs were in conversation-sized groups (which typically have a maximum size of 4: Dezecache and Dunbar 2012;Dunbar 2016;Krems et al. 2016;Dahmardeh and Dunbar 2017), whereas casual customers and those in city centre bars were typically in parties that were larger than the normative limit for conversations. Figure 3b plots how integrated into their local community people felt themselves to be (indexed by the IOS scale). ...
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Alcohol use has a long and ubiquitous history. Despite considerable research on the misuse of alcohol, no one has ever asked why it might have become universally adopted, although the conventional view assumes that its only benefit is hedonic. In contrast, we suggest that alcohol consumption was adopted because it has social benefits that relate both to health and social bonding. We combine data from a national survey with data from more detailed behavioural and observational studies to show that social drinkers have more friends on whom they can depend for emotional and other support, and feel more engaged with, and trusting of, their local community. Alcohol is known to trigger the endorphin system, and the social consumption of alcohol may thus have the same effect as the many other social activities such as laughter, singing and dancing that we use as a means of servicing and reinforcing social bonds.
... Nonetheless, the average size of lunch and dinner groups ( Fig. 3: means of 3.3 ± 1.2 and 3.6 ± 1.3 respectively, including the respondent) is virtually identical to the average size of free-forming conversational groups (~3.5: Dunbar 2016;Krems et al. 2016;Dahmardeh and Dunbar 2017). ...
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Communal eating, whether in feasts or everyday meals with family or friends, is a human universal, yet it has attracted surprisingly little evolutionary attention. I use data from a UK national stratified survey to test the hypothesis that eating with others provides both social and individual benefits. I show that those who eat socially more often feel happier and are more satisfied with life, are more trusting of others, are more engaged with their local communities, and have more friends they can depend on for support. Evening meals that result in respondents feeling closer to those with whom they eat involve more people, more laughter and reminiscing, as well as alcohol. A path analysis suggests that the causal direction runs from eating together to bondedness rather than the other way around. I suggest that social eating may have evolved as a mechanism for facilitating social bonding.
... Though ostensibly similar, mentalising (and hence identification) differs from empathy in being a form of 'cold cognition' (beliefs about mindstates), whereas empathy is a form of 'hot cognition' (emotional feelings). Higher-order mentalising (beyond formal theory of mind) not only makes it possible to parse complex utterances in speech (Oesch and Dunbar, 2017), but also limits the number of individuals whose minds we can monitor simultaneously (Stiller and Dunbar, 2007;Powell et al., 2012;Krems et al., 2016) as well as directly affecting the complexity of the stories we can enjoy (Carney et al., 2014). Without the capacity to mentalise, we would be unable to distinguish between the speaker and the mental states of the characters they describe or recognise that an actor is representing a fictional character rather than speaking their own thoughts. ...
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Fictional storytelling has played an important role in human cultural life since earliest times, and we are willing to invest significant quantities of time, mental effort and money in it. Nonetheless, the psychological mechanisms that make this possible, and how they relate to the mechanisms that underpin real-world social relationships, remain understudied. We explore three factors: identification (the capacity to identify with a character), moral approval and causal attribution with respect to a character’s behaviour in live performances of two plays from the European literary canon. There were significant correlations between the extent to which subjects identified with a character and their moral approval of that character’s behaviour that was independent of the way the play was directed. However, the subjects’ psychological explanations for a character’s behaviour (attribution) were independent of whether or not they identified with, or morally approved of, the character. These data extend previous findings by showing that moral approval plays an important role in facilitating identification even in live drama. Despite being transported by an unfolding drama, audiences do not necessarily become biased in their psychological understanding of why characters behaved as they did. The psychology of drama offers significant insights into the psychological processes that underpin our everyday social world.
... Converging lines of evidence strongly suggest that people can possess only so many close relationships, including friendships, at any one time-whether to owing to limited time in the day and/or our limited abilities to track social relationships (e.g., Dunbar, 1993Dunbar, , 2008Krems, Dunbar, & Neuberg, 2016;Krems & Wilkes, 2019;Miritello et al., 2013;Roberts & Dunbar, 2011;Roberts, Dunbar, Pollet, & Kuppens, 2009;Zhou, Sornette, Hill, & Dunbar, 2005). For example, time is required to build and also to sustain individual friendships and other social relationships (Canary & Stafford, 1994;Oswald et al., 2004;Miritello et al., 2013;Nie, 2001), but time is also notably inelastic. ...
Article
Close friendships are associated with greater happiness and improved health; historically, they would likely have provided beneficial fitness outcomes. Yet each friendship requires one's finite time and resources to develop and maintain. Because people can maintain only so many close relationships, including friendships, at any one time, choosing which prospective friends to pursue and invest in is likely to have been a recurrent adaptive problem. Moreover, not all friends are created equal; some might be kind but unintelligent, some intelligent but disloyal, and so on. How might people integrate their friend preferences to make friend choices? Work using a Euclidean model of mate preferences has had significant success in elucidating this integration challenge in the domain of mating. Here, we apply this model to the domain of friendship, specifically exploring same-sex best and close friendships. We test and find some support for several critical predictions derived from a Euclidean integration hypothesis: People with higher Euclidean friend value (a) have best friends who better fulfill their best friend preferences, (b) have higher friend-value ideal best friends, and (c) have higher friend-value actual best friends. We also (d) replicate existing similar findings with regard to mating and (e) additionally provide a first test of whether people's Euclidean friend value (versus mate value) is a better predictor of their friend outcomes, and vice versa, finding some, albeit mixed, support for the dissocialbility of these constructs.
... Since then, these have been attracting the attention of many mathematical chemists [30,39] and many others. One may refer [40][41][42][43][44][45][46][47][48][49][50][51] for some extensive works related to above directions. ...
... Second, robust research suggests that a person can maintain only so many relationships at any one time, whether because we have finite time to invest in these relationships (Dunbar, 1993(Dunbar, , 2008Milardo, Johnson, & Huston, 1983;Roberts & Dunbar, 2011;Roberts, Dunbar, Pollet, & Kuppens, 2009;Zhou, Sornette, Hill, & Dunbar, 2005), and/or because we may be able to keep close track of only so many relationship partners at once (Hall, Larson, & Watts, 2011;Krems, Dunbar, & Neuberg, 2016;Krems & Wilkes, 2019;Miritello et al., 2013;Oswald et al., 2004). For example, relationships require time to build and to maintain (e.g., Miritello et al., 2013;Oswald et al., 2004), but time is a notably inelastic resource. ...
Preprint
Full-text available
Friendships can foster happiness, health, and reproductive fitness. But friendships end—even when we might not want them to. A primary reason for this is interference from third parties. Yet little work has explored how people meet the challenge of maintaining friendships in the face of real or perceived threats from third parties, as when our friends inevitably make new friends or form new romantic relationships. In contrast to earlier conceptualizations from developmental research, which viewed friendship jealousy as solely maladaptive, we propose that friendship jealousy is one overlooked tool of friendship maintenance. We derive and test—via a series of 11 studies (N = 2918) using hypothetical scenarios, recalled real-world events, and manipulation of on-line emotional experiences—whether friendship jealousy possesses the features of a tool well-designed to help us retain friends in the face of third-party threats. Consistent with our proposition, findings suggest that friendship jealousy is (1) uniquely evoked by third-party threats to friendships (but not the prospective loss of the friendship alone), (2) sensitive to the value of the threatened friendship, (3) strongly calibrated to cues that one is being replaced, even over more intuitive cues (e.g., the amount of time a friend and interloper spend together), and (4) ultimately motivates behavior aimed at countering third-party threats to friendship (“friend guarding”). Even as friendship jealousy may be negative to experience, it may include features designed for beneficial—and arguably prosocial—ends: to help maintain friendships.
... Since then, these have been attracting the attention of many mathematical chemists [30,39] and many others. One may refer [40][41][42][43][44][45][46][47][48][49][50][51] for some extensive works related to above directions. ...
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Topological indices describe mathematical invariants of molecules in mathematical chemistry. M-polynomials of chemical graph theory have freedom about the nature of molecular graphs and they play a role as another topological invariant. Social networks can be both cyclic and acyclic in nature. We develop a novel application of M-polynomials, the ( m , n , r ) -agent recruitment graph where n > 1 , to study the relationship between the Dunbar graphs of social networks and the small-world phenomenon. We show that the small-world effects are only possible if everyone uses the full range of their network when selecting steps in the small-world chain. Topological indices may provide valuable insights into the structure and dynamics of social network graphs because they incorporate an important element of the dynamical transitivity of such graphs.
... Second, robust research suggests that a person can maintain only so many relationships at any one time, whether because we have finite time to invest in these relationships (Dunbar, 1993(Dunbar, , 2008Milardo, Johnson, & Huston, 1983;Roberts & Dunbar, 2011;Roberts, Dunbar, Pollet, & Kuppens, 2009;Zhou, Sornette, Hill, & Dunbar, 2005), and/or because we may be able to keep close track of only so many relationship partners at once (Hall, Larson, & Watts, 2011;Krems, Dunbar, & Neuberg, 2016;Krems & Wilkes, 2019;Miritello et al., 2013;Oswald et al., 2004). For example, relationships require time to build and to maintain (e.g., Miritello et al., 2013;Oswald et al., 2004), but time is a notably inelastic resource. ...
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Friendships can foster happiness, health, and reproductive fitness. However, friendships end-even when we might not want them to. A primary reason for this is interference from third parties. Yet, little work has explored how people meet the challenge of maintaining friendships in the face of real or perceived threats from third parties, as when our friends inevitably make new friends or form new romantic relationships. In contrast to earlier conceptualizations from developmental research, which viewed friendship jealousy as solely maladaptive, we propose that friendship jealousy is one overlooked tool of friendship maintenance. We derive and test-via a series of 11 studies (N = 2,918) using hypothetical scenarios, recalled real-world events, and manipulation of online emotional experiences-whether friendship jealousy possesses the features of a tool well-designed to help us retain friends in the face of third-party threats. Consistent with our proposition, findings suggest that friendship jealousy is (a) uniquely evoked by third-party threats to friendships (but not the prospective loss of the friendship alone), (b) sensitive to the value of the threatened friendship, (c) strongly calibrated to cues that one is being replaced, even over more intuitive cues (e.g., the amount of time a friend and interloper spend together), and (d) ultimately motivates behavior aimed at countering third-party threats to friendship ("friend guarding"). Even as friendship jealousy may be negative to experience, it may include features designed for beneficial-and arguably prosocial-ends: to help maintain friendships. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
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I argue that three questions are invariably overlooked in the study of religion: (1) why religions, and particularly shamanic-type religions, evolved, (2) why doctrinal religions evolved a mere 8000 years ago, and (3) why only humans have religion.
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Background Breast cancer survivors (BCS) may be limited in their ability to attend support groups due to transportation, geography, finances, and/or time. Evidence suggests that internet platforms, texting, and videoconferencing can be used to provide education and support. Objective To evaluate if participating in Virtual Breast Cancer Education and Support Group (VBCESG) sessions via Zoom® videoconferencing will change perceived satisfaction and ability for survivors to complete their chosen activities. Methods Support group flyers were posted on social media, emailed, and/or faxed to breast cancer providers and survivors to recruit participants. Inclusion criteria included participants who were diagnosed with Stage 0-III breast cancer, completed treatment, excluding HER2 suppressant and/or anti-hormone medications, and had internet access and basic computer skills. Canadian Occupational Performance Measure (COPM) was administered via Zoom® videoconferencing before the first and after the sixth VBCESG session. Based on BCS interests and information gained from the COPM and a survey, each education session was developed to address participants’ identified interests. Participants received an activity tracker to count their steps. After each session, participants completed a brief survey to provide feedback on the quality of the session. Data analysis will include descriptive and inferential statistics to assess changes in perceived performance and satisfaction of BCS important activities and step counts, and BCS satisfaction with the VBCESG. COPM and survey open-ended question responses will be analyzed thematically. Plan Results of this pilot study will inform the design and implementation of a future study to examine the perceived functional impact of VBCESG.
Article
Conversation is flexible enough to be conducted with varying numbers of individuals, but most conversation is dyadic. Is the prevalence of dyadic focal participation frameworks facilitated by structures of conversation? Using video recordings of spontaneous naturally occurring conversations, I explore multiperson interactions focusing on how structures of turn taking, sequence organization, storytelling, and speaker gaze facilitate or inhibit the inclusion of multiple individuals in conversation. As I show, because our system favors dyadic participation through turn allocation and sequence organization, sustaining focal triadic or multiparty participation frameworks requires more interactional work than sustaining a dyadic focal participation framework. However, serially dyadic participation, which keeps dyads shifting, and story- and joke telling facilitate the participation of multiple individuals. Although conversational structures can be adapted to partition focal participation as dyadic or multiparty on a moment-by-moment basis, the structures generally facilitate dyadic focal participation. Data are in American English.
Chapter
Storytelling has played a major role in human evolution as a mechanism for engineering social cohesion. In large measure, this is because a shared worldview is an important basis for the formation not just of friendships but, more generally, of social communities. Storytelling thus provides the mechanism for the transmission of shared cultural icons and shared histories within a community. That being so, the effectiveness with which stories do their job is likely to be related to the storyteller?s ability to make challenging yet realistic stories without overtaxing the listeners? abilities to comprehend the narrative. I summarise some of the constraints likely to act on this both in terms of community size and organisation and in terms of cognition, and explore their implications for storytelling.
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Although laughter is probably of deep evolutionary origin, the telling of jokes, being language-based, is likely to be of more recent origin within the human lineage. In language-based communication, speaker and listener are engaged in a process of mutually understanding each other's intentions (mindstates), with a conversation minimally requiring three orders of intentionality. Mentalizing is cognitively more demanding than non-mentalizing cognition, and there is a well-attested limit at five orders in the levels of intentionality at which normal adult humans can work. Verbal jokes commonly involve commentary on the mindstates of third parties, and each such mindstate adds an additional level of intentionality and its corresponding cognitive load. We determined the number of mentalizing levels in a sample of jokes told by well-known professional comedians and show that most jokes involve either three or five orders of intentionality on the part of the comedian, depending on whether or not the joke involves other individuals' mindstates. Within this limit there is a positive correlation between increasing levels of intentionality and subjective ratings of how funny the jokes are. The quality of jokes appears to peak when they include five or six levels of intentionality, which suggests that audiences appreciate higher mentalizing complexity whilst working within their natural cognitive constraints.
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Theory of mind (ToM)-or thinking about the mental states of others-is a cornerstone of successful everyday social interaction. However, the brain bases of ToM are most frequently measured via explicit laboratory tasks that pose direct questions about mental states (e.g., "In this story, what does Steve think Julia believes?"). Neuroanatomical measures may provide a way to explore the brain bases of individual differences in more naturalistic, everyday mentalizing. In the current study, we examined the relation between cortical thickness and spontaneous ToM using the novel Spontaneous Theory of Mind Protocol (STOMP), which measures participants' spontaneous descriptions of the beliefs, emotions, and goals of characters in naturalistic videos. We administered standard ToM tasks and the STOMP to young adults (aged 18-26 years) and collected structural MRI data from a subset of these participants. The STOMP produced robust individual variability and was correlated with performance on traditional ToM tasks. Further, unlike the traditional ToM tasks, STOMP performance was related to cortical thickness for a set of brain regions that have been functionally linked to ToM processing. These findings offer novel insight into the brain bases of variability in naturalistic mentalizing performance, with implications for both typical and atypical populations.
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Understanding others’ mental states is a crucial skill that enables the complex social relationships that characterize human societies. Yet little research has investigated what fosters this skill, which is known as Theory of Mind (ToM), in adults. We present five experiments showing that reading literary fiction led to better performance on tests of affective ToM (experiments 1 to 5) and cognitive ToM (experiments 4 and 5) compared with reading nonfiction (experiments 1), popular fiction (experiments 2 to 5), or nothing at all (experiments 2 and 5). Specifically, these results show that reading literary fiction temporarily enhances ToM. More broadly, they suggest that ToM may be influenced by engagement with works of art.
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Hyperlink cinema is an emergent film genre that seeks to push the boundaries of the medium in order to mirror contemporary life in the globalized community. Films in the genre thus create an interacting network across space and time in such a way as to suggest that people's lives can intersect on scales that would not have been possible without modern technologies of travel and communication. This allows us to test the hypothesis that new kinds of media might permit us to break through the natural cognitive constraints that limit the number and quality of social relationships we can manage in the conventional face-to-face world. We used network analysis to test this hypothesis with data from 12 hyperlink films, using 10 motion pictures from a more conventional film genre as a control. We found few differences between hyperlink cinema films and the control genre, and few differences between hyperlink cinema films and either the real world or classical drama (e.g., Shakespeare's plays). Conversation group size seems to be especially resilient to alteration. It seems that, despite many efficiency advantages, modern media are unable to circumvent the constraints imposed by our evolved psychology.
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Drama, at least according to the Aristotelian view, is effective inasmuch as it successfully mirrors real aspects of human behavior. This leads to the hypothesis that successful dramas will portray fictional social networks that have the same properties as those typical of human beings across ages and cultures. We outline a methodology for investigating this hypothesis and use it to examine ten of Shakespeare’s plays. The cliques and groups portrayed in the plays correspond closely to those which have been observed in spontaneous human interaction, including in hunter-gatherer societies, and the networks of the plays exhibit “small world” properties of the type which have been observed in many human-made and natural systems.
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Psychological studies of relationships tend to focus on specific types of close personal relationships (romantic, parent-offspring, friendship) and examine characteristics of both the individuals and the dyad. This paper looks more broadly at the wider range of relationships that constitute an individual's personal social world. Recent work on the composition of personal social networks suggests that they consist of a series of layers that differ in the quality and quantity of relationships involved. Each layer increases relationship numbers by an approximate multiple of 3 (5-15-50-150) but decreasing levels of intimacy (strong, medium, and weak ties) and frequency of interaction. To account for these regularities, we draw on both social and evolutionary psychology to argue that relationships at different layers serve different functions and have different cost-benefit profiles. At each layer, the benefits are asymptotic but the costs of maintaining a relationship at that level (most obviously, the time that has to be invested in servicing it) are roughly linear with the number of relationships. The trade-off between costs and benefits at a given level, and across the different types of demands and resources typical of different levels, gives rise to a distribution of social effort that generates and maintains a hierarchy of layered sets of relationships within social networks. We suggest that, psychologically, these trade-offs are related to the level of trust in a relationship, and that this is itself a function of the time invested in the relationship.
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The social brain hypothesis, an explanation for the unusually large brains of primates, posits that the size of social group typical of a species is directly related to the volume of its neocortex. To test whether this hypothesis also applies at the within-species level, we applied the Cavalieri method of stereology in conjunction with point counting on magnetic resonance images to determine the volume of prefrontal cortex (PFC) subfields, including dorsal and orbital regions. Path analysis in a sample of 40 healthy adult humans revealed a significant linear relationship between orbital (but not dorsal) PFC volume and the size of subjects' social networks that was mediated by individual intentionality (mentalizing) competences. The results support the social brain hypothesis by indicating a relationship between PFC volume and social network size that applies within species, and, more importantly, indicates that the relationship is mediated by social cognitive skills.
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Evidence for successful socio-cognitive training in typical adults is rare. This study attempted to improve Theory of Mind (ToM) and visual perspective taking in healthy adults by training participants to either imitate or to inhibit imitation. Twenty-four hours after training, all participants completed tests of ToM and visual perspective taking. The group trained to inhibit their tendency to imitate showed improved performance on the visual perspective-taking test, but not the ToM test. Neither imitation training, nor general inhibition training, had this effect. These results support a novel theory of social cognition suggesting that the same self-other discrimination process underlies imitation inhibition and perspective taking. Imitation, perspective taking and ToM are all pro-social processes--ways in which we reach out to others. Therefore, it is striking that perspective taking can be enhanced by suppressing imitation; to understand another, sometimes we need, not to get closer, but to pull away.
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Miller (1956) summarized evidence that people can remember about seven chunks in short-term memory (STM) tasks. However, that number was meant more as a rough estimate and a rhetorical device than as a real capacity limit. Others have since suggested that there is a more precise capacity limit, but that it is only three to five chunks. The present target article brings together a wide variety of data on capacity limits suggesting that the smaller capacity limit is real. Capacity limits will be useful in analyses of information processing only if the boundary conditions for observing them can be carefully described. Four basic conditions in which chunks can be identified and capacity limits can accordingly be observed are: (1) when information overload limits chunks to individual stimulus items, (2) when other steps are taken specifically to block the recording of stimulus items into larger chunks, (3) in performance discontinuities caused by the capacity limit, and (4) in various indirect effects of the capacity limit. Under these conditions, rehearsal and long-term memory cannot be used to combine stimulus items into chunks of an unknown size; nor can storage mechanisms that are not capacity-limited, such as sensory memory, allow the capacity-limited storage mechanism to be refilled during recall. A single, central capacity limit averaging about four chunks is implicated along with other, noncapacity-limited sources. The pure STM capacity limit expressed in chunks is distinguished from compound STM limits obtained when the number of separately held chunks is unclear. Reasons why pure capacity estimates fall within a narrow range are discussed and a capacity limit for the focus of attention is proposed.
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Feeding relationships can cause invasions, extirpations, and population fluctuations of a species to dramatically affect other species within a variety of natural habitats. Empirical evidence suggests that such strong effects rarely propagate through food webs more than three links away from the initial perturbation. However, the size of these spheres of potential influence within complex communities is generally unknown. Here, we show for that species within large communities from a variety of aquatic and terrestrial ecosystems are on average two links apart, with >95% of species typically within three links of each other. Species are drawn even closer as network complexity and, more unexpectedly, species richness increase. Our findings are based on seven of the largest and most complex food webs available as well as a food-web model that extends the generality of the empirical results. These results indicate that the dynamics of species within ecosystems may be more highly interconnected and that biodiversity loss and species invasions may affect more species than previously thought.
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The 'social brain hypothesis' for the evolution of large brains in primates has led to evidence for the coevolution of neocortical size and social group sizes, suggesting that there is a cognitive constraint on group size that depends, in some way, on the volume of neural material available for processing and synthesizing information on social relationships. More recently, work on both human and non-human primates has suggested that social groups are often hierarchically structured. We combine data on human grouping patterns in a comprehensive and systematic study. Using fractal analysis, we identify, with high statistical confidence, a discrete hierarchy of group sizes with a preferred scaling ratio close to three: rather than a single or a continuous spectrum of group sizes, humans spontaneously form groups of preferred sizes organized in a geometrical series approximating 3-5, 9-15, 30-45, etc. Such discrete scale invariance could be related to that identified in signatures of herding behaviour in financial markets and might reflect a hierarchical processing of social nearness by human brains.
Chapter
This chapter has three main objectives. First, it briefly summarizes the reasons why language might have evolved, and what we are to make of these. It then considers what this has to tell us about why only the hominin lineage evolved the capacity for language. Finally, it revisits the author's previous analyses (Aiello and Dunbar 1993) on the timing of language evolution in the hominin fossil record using new estimates for all the equations involved, in order to explore the sequence by which language might have evolved, and the transitional states involved.
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Man-environment relations is such a broad field that a researcher has to choose his audience as well as his problem area. Over the years, I have had three different audiences in mind, which has meant writing three different kinds of articles. The first contained various social scientists. Interestingly, sociologists have been far more receptive to studies of spatial behavior than have psychologists who tend to think in terms of psychological rather than physical spaces. Anthropologists were interested in the work from the standpoint of non-verbal communication. Because I want to change the world, I also aimed at architects, landscape people and others concerned with the design of the physical environment, and space managers such as hospital administrators, student housing directors, school principals and air terminal managers who are directly responsible for the furnishing, allocation, and utilization of institutional spaces. It is noteworthy that animal biologists and ecologists, whom I have never tried to reach directly, are the people to whom I am most indebted for my theoretical orientation and concepts.
Article
Human conversation groups have a characteristic size limit at around four individuals. Although mixed-sex social groups can be significantly larger than this, census data on casual social groups suggest that there is a fractal pattern of fission in conversations when social group size is a multiple of this value. This study suggests that, as social group size increases beyond four, there is a tendency for sexual segregation to occur resulting in an increasing frequency of single-sex conversational subgroups. It is not clear why conversations fragment in this way, but a likely explanation is that sex differences in conversational style result in women (in particular) preferring to join all-female conversations when a social group is large enough to allow this.
Article
Conventional wisdom over the past 160 years in the cognitive and neurosciences has assumed that brains evolved to process factual information about the world. Most attention has therefore been focused on such features as pattern recognition, color vision, and speech perception. By extension, it was assumed that brains evolved to deal with essentially ecological problem-solving tasks. 1.
Article
Data from various settings suggest that there is an upper limit of about four on the number of individuals who can interact in spontaneous conversation. This limit appears to be a consequence of the mechanisms of speech production and detection. There appear to be no differences between men and women in this respect, other than those introduced by women's lighter voices.
Article
Recent studies suggest that laughter plays an important role in social bonding. Human communities are much larger than those of other primates and hence require more time to be devoted to social maintenance activities. Yet, there is an upper limit on the amount of time that can be dedicated to social demands, and, in nonhuman primates, this sets an upper limit on social group size. It has been suggested that laughter provides the additional bonding capacity in humans by allowing an increase in the size of the “grooming group.” In this study of freely forming laughter groups, we show that laughter allows a threefold increase in the number of bonds that can be “groomed” at the same time. This would enable a very significant increase in the size of community that could be bonded.
Article
Previous work on Shakespearian plays has shown that the structure of these dramas reflects the levels of grouping found in a variety of human societies. In this paper, we use data from soap operas to investigate whether this form of narrative drama also displays evidence of this form of social structuring. Data from ten weekly serials were analysed and revealed that mean scene size (number of speaking characters per scene) was similar to that previously found for Shakespearian plays, and also similar to the mean size of naturally forming conversational groups. This group size is usually identified as corresponding to individual “support cliques” in the literature. The number of recurring characters appearing per episode and per week of episodes was also similar to that found for Shakespeare's plays and corresponded to the size of human “sympathy groups”. A questionnaire study administered to 30 respondents revealed that individuals maintained an average of 85.8 “para-social” television-based relationships. However, since they also apparently had real social networks of conventional size, the data do not suggest that individuals who are avid followers of TV soaps necessarily do so because they are less sociable than those who do not.
Article
The intentional stance is the strategy of prediction and explanation that attributes beliefs, desires, and other “intentional” states to systems – living and nonliving – and predicts future behavior from what it would be rational for an agent to do, given those beliefs and desires. Any system whose performance can be thus predicted and explained is an intentional system, whatever its innards. The strategy of treating parts of the world as intentional systems is the foundation of “folk psychology,” but is also exploited (and is virtually unavoidable) in artificial intelligence and cognitive science more generally, as well as in evolutionary theory. An analysis of the role of the intentional stance and its presuppositions supports a naturalistic theory of mental states and events, their content or intentionality, and the relation between “mentalistic” levels of explanation and neurophysiological or mechanistic levels of explanation. As such, the analysis of the intentional stance grounds a theory of the mind and its relation to the body.
Article
The ability to understand and conceptualize the mental processes of other people is considered to play a vital role in social interactions. Deficits in this area, sometimes known as theory-of-mind (ToM) deficits, have been identified as playing a possible causal role in autism, Asperger's syndrome and schizophrenic disorders, particularly paranoia. Paranoia has also been associated with an abnormal attributional style, an observation that suggests that ToM and attributional processes may be related phenomena. This paper describes a study examining the relationship between attributional processes and ToM deficits. Seventy-seven undergraduate participants completed a ToM task and forty-six also completed the Internal, Personal and Situational Attributions Questionnaire (IPSAQ). ToM deficits were associated with an increased tendency to identify other individuals as responsible for negative social situations. The implications of the observed relationship between attributions and ToM deficits are discussed.
Article
Food-web structure mediates dramatic effects of biodiversity loss including secondary and `cascading' extinctions. We studied these effects by simulating primary species loss in 16 food webs from terrestrial and aquatic ecosystems and measuring robustness in terms of the secondary extinctions that followed. As observed in other networks, food webs are more robust to random removal of species than to selective removal of species with the most trophic links to other species. More surprisingly, robustness increases with food-web connectance but appears independent of species richness and omnivory. In particular, food webs experience `rivet-like' thresholds past which they display extreme sensitivity to removal of highly connected species. Higher connectance delays the onset of this threshold. Removing species with few trophic connections generally has little effect though there are several striking exceptions. These findings emphasize how the number of species removed affects ecosystems differently depending on the trophic functions of species removed.
Article
Human social networks typically consist of a hierarchically organized series of grouping levels. There is, however, considerable variation between individuals in the sizes of any given network layer. We test between two possible factors (memory capacity and theory of mind) that might limit the size of two different levels within human social networks (support cliques and sympathy groups). We show that the size of an individual's support clique (the number of individual's in the innermost circle of friends) is better explained by individual differences in social cognition (mentalising skills). However, the size of the sympathy group (the most frequent social partners) is better explained by individual's performance on memory tasks.
Article
The co-authorship network of scientists represents a prototype of complex evolving networks. In addition, it offers one of the most extensive database to date on social networks. By mapping the electronic database containing all relevant journals in mathematics and neuro-science for an 8-year period (1991–98), we infer the dynamic and the structural mechanisms that govern the evolution and topology of this complex system. Three complementary approaches allow us to obtain a detailed characterization. First, empirical measurements allow us to uncover the topological measures that characterize the network at a given moment, as well as the time evolution of these quantities. The results indicate that the network is scale-free, and that the network evolution is governed by preferential attachment, affecting both internal and external links. However, in contrast with most model predictions the average degree increases in time, and the node separation decreases. Second, we propose a simple model that captures the network's time evolution. In some limits the model can be solved analytically, predicting a two-regime scaling in agreement with the measurements. Third, numerical simulations are used to uncover the behavior of quantities that could not be predicted analytically. The combined numerical and analytical results underline the important role internal links play in determining the observed scaling behavior and network topology. The results and methodologies developed in the context of the co-authorship network could be useful for a systematic study of other complex evolving networks as well, such as the world wide web, Internet, or other social networks.
Article
Cognitive abilities such as Theory of Mind (ToM), and more generally mentalizing competences, are central to human sociality. Neuroimaging has associated these abilities with specific brain regions including temporo-parietal junction, superior temporal sulcus, frontal pole, and ventromedial prefrontal cortex. Previous studies have shown both that mentalizing competence, indexed as the ability to correctly understand others' belief states, is associated with social network size and that social group size is correlated with frontal lobe volume across primate species (the social brain hypothesis). Given this, we predicted that both mentalizing competences and the number of social relationships a person can maintain simultaneously will be a function of gray matter volume in these regions associated with conventional Theory of Mind. We used voxel-based morphometry of Magnetic Resonance Images (MRIs) to test this hypothesis in humans. Specifically, we regressed individuals' mentalizing competences and social network sizes against gray matter volume. This revealed that gray matter volume in bilateral posterior frontal pole and left temporoparietal junction and superior temporal sucus varies parametrically with mentalizing competence. Furthermore, gray matter volume in the medial orbitofrontal cortex and the ventral portion of medial frontal gyrus, varied parametrically with both mentalizing competence and social network size, demonstrating a shared neural basis for these very different facets of sociality. These findings provide the first fine-grained anatomical support for the social brain hypothesis. As such, they have important implications for our understanding of the constraints limiting social cognition and social network size in humans, as well as for our understanding of how such abilities evolved across primates.
Article
Networks of coupled dynamical systems have been used to model biological oscillators, Josephson junction arrays, excitable media, neural networks, spatial games, genetic control networks and many other self-organizing systems. Ordinarily, the connection topology is assumed to be either completely regular or completely random. But many biological, technological and social networks lie somewhere between these two extremes. Here we explore simple models of networks that can be tuned through this middle ground: regular networks 'rewired' to introduce increasing amounts of disorder. We find that these systems can be highly clustered, like regular lattices, yet have small characteristic path lengths, like random graphs. We call them 'small-world' networks, by analogy with the small-world phenomenon (popularly known as six degrees of separation. The neural network of the worm Caenorhabditis elegans, the power grid of the western United States, and the collaboration graph of film actors are shown to be small-world networks. Models of dynamical systems with small-world coupling display enhanced signal-propagation speed, computational power, and synchronizability. In particular, infectious diseases spread more easily in small-world networks than in regular lattices.
Article
Speech‐intelligibility scores as a function of noise level are studied for face‐to‐face, sound‐powered‐phone, and amplified speech(earphone and loudspeaker) communication conditions. The speech‐interference level (SIL) for octaves of noise centered at 500, 1000, and 2000 cps (0.5/1/2) is used as the measure of noise level. By using this noise measure, much of the work in this field can be brought together and interpreted. It is noted that “noisy” and “very noisy” spaces are associated with SIL&apos;s such that “shouting” or “very loud” voice levels (or 95‐dB speech levels) are required for conversations at 1.5 or 3 ft, and this is the region where telephone conversations are judged to be “difficult” or “unsatisfactory.” All of these adverse noise conditions occur at the region where ear protection will aid intelligibility and at the boundary where ear protection should be used to protect against hearing losses. Where people must converse or communicate via some interior communication device, 0.5/1/2 SIL&apos;s above 70 dB should be avoided. At 0.5/1/2 SIL&apos;s greater than 90 dB, the wearing of hearing protection should be made mandatory and every noiseproofing technique (except a noise shield for the microphone) should be employed. At 0.5/1/2 SIL&apos;s above 100 dB, every noise‐proofing technique should be employed
Close social relationships: an evolutionary perspective
  • Sbg Roberts
  • H Arrow
  • J Lehmann
  • Dunbar
  • Rim
Roberts, SBG, Arrow, H, Lehmann, J, & Dunbar, RIM (2014). Close social relationships: an evolutionary perspective. Lucy to language: the benchmark papers (pp. 151-180). Oxford: Oxford University Press.
  • J A Krems
J.A. Krems et al. / Evolution and Human Behavior 37 (2016) 423–428
The complete Moby ™ Shakespeare Reading literary fiction improves theory of mind
  • J Hylton
Hylton, J. (n.d.). The complete Moby ™ Shakespeare. Retrieved September 3, 2013, from http://shakespeare.mit.edu Kidd, DC, & Castano, E (2013). Reading literary fiction improves theory of mind. Science, 342(6156), 377–380.
The strategic bystander: theory of mind and common knowledge in decision to help. Paper presented at the meeting of the human behavior and evolution society Columbia
  • J Defreitas
  • K A Thomas
  • P D Descioli
  • S Pinker
DeFreitas, J, Thomas, KA, DeScioli, PD, & Pinker, S (2015). The strategic bystander: theory of mind and common knowledge in decision to help. Paper presented at the meeting of the human behavior and evolution society Columbia, MO.
The complete Moby ™ Shakespeare
  • J Hylton
Hylton, J. (n.d.). The complete Moby ™ Shakespeare. Retrieved September 3, 2013, from http://shakespeare.mit.edu