Kevin Lewis

December 23, 2018

Shared Plates, Shared Minds: Consuming from a Shared Plate Promotes Cooperation
Kaitlin Woolley & Ayelet Fishbach
Psychological Science, forthcoming

A meal naturally brings people together, but does the way a meal is served and consumed further matter for cooperation between people? This research (n = 1476) yielded evidence that it does. People eating from shared plates (i.e., Chinese style meal) cooperated more in social dilemmas and negotiations than those eating from separate plates. Specifically, sharing food from a single plate increased perceived coordination among diners, which in turn led them to behave more cooperatively and less competitively toward each other compared with individuals eating the same food from separate plates. The effect of sharing a plate on cooperation occurred among strangers, which suggests that sharing plates can bring together not only allies, but strangers as well.

Handshaking promotes deal-making by signaling cooperative intent
Juliana Schroeder et al.
Journal of Personality and Social Psychology, forthcoming

We examine how a simple handshake - a gesture that often occurs at the outset of social interactions - can influence deal-making. Because handshakes are social rituals, they are imbued with meaning beyond their physical features. We propose that during mixed-motive interactions, a handshake is viewed as a signal of cooperative intent, increasing people's cooperative behavior and affecting deal-making outcomes. In Studies 1a and 1b, pairs who chose to shake hands at the onset of integrative negotiations obtained better joint outcomes. Study 2 demonstrates the causal impact of handshaking using experimental methodology. Study 3 suggests a driver of the cooperative consequence of handshaking: negotiators expected partners who shook hands to behave more cooperatively than partners who avoided shaking hands or partners whose nonverbal behavior was unknown; these expectations of cooperative intent increased negotiators' own cooperation. Study 4 uses an economic game to demonstrate that handshaking increased cooperation even when handshakes were uninstructed (vs. instructed). Further demonstrating the primacy of signaling cooperative intent, handshaking actually reduced cooperation when the action signaled ill intent (e.g., when the hand-shaker was sick; Study 5). Finally, in Study 6, executives assigned to shake hands before a more antagonistic, distributive negotiation were less likely to lie about self-benefiting information, increasing cooperation even to their own detriment. Together, these studies provide evidence that handshakes, ritualistic behaviors imbued with meaning beyond mere physical contact, signal cooperative intent and promote deal-making.

Costs and benefits of acting extraverted: A randomized controlled trial
Rowan Jacques-Hamilton, Jessie Sun & Luke Smillie
Journal of Experimental Psychology: General, forthcoming

Evidence suggests that extraverted (i.e., bold, agentic) behavior increases positive affect (PA), and could be targeted in wellbeing interventions. However, this evidence is either causally ambiguous or has questionable ecological validity, and the potential costs of sustained extraverted behavior have received minimal attention. To address these limitations, we conducted a randomized controlled trial examining the wellbeing benefits and costs of an extraverted behavior intervention conducted in everyday life. Participants (n = 147) were randomly assigned to an "act-extraverted" intervention or a "sham" (active control) intervention for 1 week in everyday life. Additional data for a contact control condition were obtained from a previous study (n = 76). Wellbeing outcomes included PA and negative affect (NA), feelings of authenticity, and tiredness - assessed both in the moment and retrospectively. There was a positive overall effect of the acting extraverted intervention on PA and authenticity. However, wellbeing outcomes also depended on dispositional extraversion: more introverted participants had weaker PA increases, experienced increased NA and tiredness, and decreased feelings of authenticity. Implications for wellbeing interventions and personality theory are discussed.

Intellectual, narcissistic, or Machiavellian? How Twitter users differ from Facebook-only users, why they use Twitter, and what they tweet about
Tara Marshall et al.
Psychology of Popular Media Culture, forthcoming

Twitter is one of the world's most popular social networking sites, yet gaps remain in our knowledge about the psychology of its users. The current studies sought to fill these gaps by examining whether the Big Five and Dark Triad personality traits predicted differences between Twitter users and Facebook-only users, motives for using Twitter, the frequency of tweeting about 4 topics - intellectual pursuits, personal achievements, diet/exercise, and social activities - and how much they liked to read tweets about these topics. Study 1 found that Twitter users (N = 346) were higher in openness (i.e., intellect and creativity) than Facebook-only users (N = 268). In Study 2, a preregistered replication, Twitter users (N = 255) were not only higher in openness than Facebook-only users (N = 248), but they were also more Machiavellian. In both studies, Twitter users who were higher in openness were more strongly motivated to use Twitter for career promotion, and in turn, they tweeted more frequently and most liked to read tweets about intellectual pursuits. Narcissists were more strongly motivated to use Twitter for career promotion, social connection, and attention-seeking, and in turn, they tweeted more frequently and most liked to read tweets about personal achievements and diet/exercise. On average, participants most liked to read tweets about intellectual pursuits and least liked tweets about diet/exercise. We discuss the implications of these findings for tailoring one's tweets to retain followers and for drawing the boundary conditions when extrapolating from Twitter-based "big data" to larger populations.

The Contrasting Effects of Performance Incentives: How Exposure to Incentives Shape Social Interactions Within and Outside Organizations
Julia Hur, Alice Lee-Yoon & Ashley Whillans
Harvard Working Paper, October 2018

Employees today report being too busy to talk with their friends and family, even though the number of hours that employees work has remained relatively constant over the last five decades. To explain this paradox, we explore the role of incentive systems in shaping how employees think about and allocate time to their social relationships. Across 4 studies (n = 132,139), we examine how exposure to performance incentives shape employees' social interactions. Results from one archival dataset, one panel survey, and two experiments show that when employees' pay is contingent on performance, they prioritize spending time with work ties at the sacrifice of spending time with personal ties. We also document a mechanism for these results: employees who are rewarded for their performance perceive work ties as more instrumental. These results are strongest when performance incentives are based on peer evaluations and administered to employees (vs. managers). These findings provide the first empirical evidence incentives shape employees' social interactions both within and outside of the workplace, potentially providing a novel explanation for the dissolution of familial and close ties in North America.

Norm talk and human cooperation: Can we talk ourselves into cooperation?
Daniel Shank et al.
Journal of Personality and Social Psychology, forthcoming

Norm talk is verbal communication that explicitly states or implicitly implies a social norm. To investigate its ability to shape cultural dynamics, 2 types of norm talk were examined: injunction, which explicitly states what should be done, and gossip, which implies a norm by stating an action approved or disapproved of by the communicator. In 2 experiments, participants engaged in norm talk in repeated public goods games. Norm talk was found to help sustain cooperation relative to the control condition; immediately after every norm talk opportunity, cooperation spiked, followed by a gradual decline. Despite the macrolevel uniformity in their effects on cooperation, evidence suggests different microlevel mechanisms for the cooperation-enhancing effects of injunction and gossip. A 3rd study confirmed that both injunction and gossip sustain cooperation by making salient the norm of cooperation, but injunction also effects mutual verification of the communicated norm, whereas gossip emphasizes its reputational implications by linking cooperation to status conferral and noncooperation to reputational damage. A 4th experiment provided additional evidence that norm talk was superior to the promise of conditional cooperation in sustaining cooperation. Implications of the findings for cultural dynamics are discussed in terms of how feelings of shared morality, language-based interpersonal communication, and ritualization of norm communication contribute to social regulation.

The strength of long-range ties in population-scale social networks
Patrick Park, Joshua Blumenstock & Michael Macy
Science, 21 December 2018, Pages 1410-1413

Long-range connections that span large social networks are widely assumed to be weak, composed of sporadic and emotionally distant relationships. However, researchers historically have lacked the population-scale network data needed to verify the predicted weakness. Using data from 11 culturally diverse population-scale networks on four continents - encompassing 56 million Twitter users and 58 million mobile phone subscribers - we find that long-range ties are nearly as strong as social ties embedded within a small circle of friends. These high-bandwidth connections have important implications for diffusion and social integration.

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