Oxytocin promotes coordinated out-group attack during intergroup conflict in humans
Open accessPublished version of a preprint
Abstract
Intergroup conflict contributes to human discrimination and violence, but persists because individuals make costly contributions to their group’s fighting capacity. Yet how group members effectively coordinate their contributions during intergroup conflict remains poorly understood. Here we examine the role of oxytocin for (the coordination of) contributions to group attack or defense in a multi-round, real-time feedback economic contest. In a double-blind placebo-controlled study with N=480 males in an Intergroup Attacker-Defender contest game, we found that oxytocin reduced contributions to attack and over time increased attacker’s within-group coordination of contributions. However, rather than becoming peaceful, attackers given oxytocin better tracked their rival’s historical defense and coordinated their contributions into well-timed and hence more profitable attacks. Our results reveal coordination of contributions as a critical component of successful attacks and subscribe to the possibility that oxytocin enables individuals to contribute to in-group efficiency and prosperity even when doing so implies outsiders are excluded or harmed. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
AI snapshot
Written from the paper’s full text.
TL;DR
In a double-blind placebo-controlled Intergroup Attacker-Defender contest with 480 healthy males, intranasal oxytocin reduced contributions to attack and increased within-group coordination of attack over time, without increasing victories. Oxytocin-treated attackers better tracked rivals’ historical defense and coordinated well-timed attacks, yielding higher leftovers when attacks failed and marginally higher spoils when successful.
Key findings
- Oxytocin vs placebo lowered average contributions (M ± SE = 6.28 ± 0.27 vs. 7.08 ± 0.30; F(1,78) = 3.719, p = 0.057) and increased non-contributors in attacker groups, especially under simultaneous decision-making (Role × Treatment, F(1,78) = 5.043, p = 0.028; simultaneous F(1,78) = 5.712, p = 0.019).
- Oxytocin improved within-group coordination (lower variance) for out-group attack but not in-group defense, especially in earlier rounds (Role × Treatment × Round, F(14,1092) = 1.753, p = 0.041); ICC increased in attacker groups under simultaneous decision-making (t(78) = 2.057, p = 0.043).
- Attack victories were similar under oxytocin and placebo (24.8 ± 1.8% vs. 26.6 ± 1.6%; F(1,78) = 0.572, p = 0.452), but oxytocin groups had higher leftovers when attacks failed (t(78) = 2.609, p = 0.011, Cohen’s d = 0.581) and marginally higher spoils when attacks succeeded (t(74) = 1.819, p = 0.073).
- Under simultaneous decisions, oxytocin increased tracking of the rival’s past defense (α = −0.30 ± 0.05 vs. −0.042 ± 0.098; t(78) = −2.334, p = 0.022); mediation showed oxytocin’s effect on spoils via tracking and coordination (indirect effect = 0.147, SE = 0.103, 95% CI 0.019 to 0.511).
Methods
- Double-blind placebo-controlled between-subjects design: 486 healthy males recruited, 480 analyzed across 80 IADC sessions (age 18–29 years; M ± SE = 20.28 ± 0.09); participants received 24 IU intranasal oxytocin or placebo about 35 min before the task.
- Intergroup Attacker-Defender Contest: six strangers per session randomly assigned to 3-person attacker and defender groups; each round gave 20 MU endowment; two 15-round blocks (simultaneous vs. sequential decision-making, order counterbalanced) with real-time feedback.
- Group-level analyses used mixed-model ANOVA for contributions, non-contributors, within-group variance/ICC, success, leftovers, and spoils; regression of attack on rival’s historical defense (α); and bootstrapped mediation.
Limitations
- Paper-stated: only Chinese males participated, and it is unclear how exogenous intranasal oxytocin operates at the neurophysiological level.
- Evident from the text: the all-male sample leaves female generalization untested despite the authors’ cautious claim; the oxytocin effect on contributions was marginal (p = 0.057) and the spoils effect was marginal (p = 0.073); no endogenous oxytocin measure is reported.
Model-written summary. Check it against the paper before relying on it.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
0 of 48 cited sources checked · 0 supported · 0 flagged
- Findingown data
There were more non-contributing attackers when attack failed than succeeded.
“There were more non-contributing attackers when attack failed than succeeded (Failure vs. Success: M ± SE = 1.68 ± 0.60 vs. 0.37 ± 0.05, F (1, 74) = 636.941, p < 0.001; η2 = 0.891).”
Quote in the paperNot a substantial claim - Findingown data
Lower within-group variance was associated with higher attacker's spoils when winning.
“the lower within-group variance when contributing, the higher the attacker’s spoils when winning the conflict (r = −0.328, p=0.004, Figure 6C).”
Quote in the paperSubstantial claim- Rests on an assumption: Lower within-group variance in contributions indicates better coordination.
- Findingown data
When decisions were made simultaneously, attack regressed more strongly on α under oxytocin than placebo.
“when decisions were made simultaneously, attack regressed more strongly on α when groups received oxytocin (M ± SE: -0.30 ± 0.05) rather than placebo (M ± SE: -0.042 ± 0.098; t(78) = -2.334; p = 0.022, Cohen’s d = -0.522, 95% CI, -0.482 to -0.038)”
Quote in the paperSubstantial claim- Rests on an assumption: The past defense parameter α captures the rival’s vulnerability.
- Findingown data
Contributions to in-group defense were higher than to out-group attack, especially in earlier rounds.
“Figure 3A showed higher contributions to in-group defense than to out-group attack, especially in earlier rounds (Role, F(1, 78) = 287.903, p < 0.001; η2 = 0.787; Role × Round, F(14, 65) = 4.529, p < 0.001, η2 = 0.494).”
Quote in the paperNot a substantial claim - Findingown data
There were more non-contributors in attacker compared to defender groups.
“There were more non-contributors in attacker compared to defender groups (M ± SE = 20.23 ± 0.90 vs. 4.25 ± 0.44; F(1, 78) = 408.489, p < 0.001; η2 = 0.840)”
Quote in the paperSubstantial claim
- Findingown data
Oxytocin increased the speed with which individuals in attacker groups decided not to contribute.
“Oxytocin increased the speed with which individuals in attacker groups decided to not contribute (Treatment × Contribute: F(1, 77) = 4.857, p = 0.031; η2 = 0.059, Figure 4).”
Quote in the paperSubstantial claim - Findingown data
The distribution of attacker groups under oxytocin and placebo indicates a clear separation, especially under simultaneous decision-making.
“The distribution of attacker groups under oxytocin and placebo in a space defined by the two vectors (contribution and payment) indicates a clear separation of oxytocin and placebo treatments (especially when decisions were made simultaneously, that is black dots vs. grey dots).”
Quote in the paperSubstantial claim - Findingown data
Attacker's higher spoils under oxytocin was mediated by increased tracking of defender group's past investments and increased within-group coordination.
“Indirect mediation analyses confirmed that the attacker’s higher spoils under oxytocin was mediated by (i) increased tracking of defender group’s past investments and (ii) concomitant increased within-group coordination (indirect effect = 0.147, SE = 0.103; 95% CI, 0.019 to 0.511, Figure 6D).”
Quote in the paperSubstantial claim- Rests on an assumption: Lower within-group variance in contributions indicates better coordination.
- Rests on an assumption: The past defense parameter α captures the rival’s vulnerability.
- Findingown data
Oxytocin reduced individual contributions to out-group attack compared to placebo.
“we found that oxytocin reduced contributions to attack and over time increased attacker’s within-group coordination of contributions.”
- Also stated in: § Results · plain
“oxytocin decreased contributions to attack (a shift toward less contribution) but increased payment (a shift toward more payment).”
Quote in the paperSubstantial claim- Rests on an assumption: Intranasal oxytocin reaches relevant brain regions and produces the intended neurobiological effects in this study.
- Rests on an assumption: Oxytocin and placebo groups were comparable at baseline.
- Also stated in: § Results · plain
- Findingown data
The oxytocin-induced increase in non-contributing attackers was stronger under simultaneous than sequential decision-making.
“This Role × Treatment effect is especially true when decisions were made simultaneously (F(1, 78) = 5.712, p = 0.019, η2 = 0.068) but less so when decisions were made sequentially (F(1, 78) = 2.143, p = 0.147; η2 = 0.027).”
Quote in the paperNot a substantial claim- Rests on an assumption: The number of non-contributors reflects strategic refraining from attack.
- Findingown data
Groups given oxytocin had higher leftovers when attacks failed.
“groups given oxytocin rather than placebo had higher leftovers when attacks failed (t(78) = 2.609, p=0.011, Cohen’s d = 0.581, 95% Confidence Interval (CI), 0.232 to 1.76, Figure 5B)”
Quote in the paperSubstantial claim - Findingown data
Under oxytocin but not placebo, the regression on α was stronger in simultaneous than sequential decision-making.
“under oxytocin but not placebo, the regression on α was also stronger in simultaneous rather than sequential decision-making (Treatment × Procedure interaction, F(1, 78) = 8.312, p = 0.005, η2 = 0.097, Figure 6A).”
Quote in the paperNot a substantial claim- Rests on an assumption: The past defense parameter α captures the rival’s vulnerability.
- Findingown data
Individuals contributed more under sequential than simultaneous decision-making.
“Individuals contributed more under sequential than simultaneous decision-making (M ± SE = 6.89 ± 0.20 vs. 6.47 ± 0.24; F(1, 78) = 5.109, p = 0.027, η2 = 0.061)”
Quote in the paperNot a substantial claim - Findingown data
Groups given oxytocin had somewhat higher spoils when attacks were successful (marginal significance).
“somewhat higher spoils when attacks were successful (t(74) = 1.819, p=0.073, Cohen’s d = 0.419, 95% CI, −0.086 to 1.888, marginal significance, Figure 5C).”
Quote in the paperNot a substantial claim - Findingown data
Individuals in attacker groups made decisions not to contribute faster than decisions to contribute.
“individuals in attacker groups made their decisions to not contribute faster than to contribute (F(1, 78) =137.679, p < 0.001, η2 = 0.641).”
Quote in the paperNot a substantial claim - Findingown data
Attacker groups given oxytocin tracked their rival's past defense and attacked especially when defenders appeared more rather than less vulnerable (attack regressed negatively on rival's historical defense).
“attacker groups given oxytocin tracked their rival’s past defense and attacked especially when defenders appeared more rather than less vulnerable (i.e. attack regressed negatively on rival’s historical defense).”
Quote in the paperSubstantial claim- Rests on an assumption: The past defense parameter α captures the rival’s vulnerability.
- Findingown data
The number of victories was similar in attacker groups given oxytocin and placebo.
“the number of victories was similar in attacker groups given oxytocin (M ± SE: 24.8 ± 1.8%) and placebo (M ± SE: 26.6 ± 1.6%), (F(1, 78)=0.572, p=0.452; η2 = 0.007).”
Quote in the paperSubstantial claim - Findingown data
There were more non-contributors in groups given oxytocin than placebo.
“more non-contributors in groups given oxytocin than placebo (M ± SE = 13.46 ± 0.90 vs. 11.01 ± 0.75; F(1,78) = 4.345, p = 0.040; η2 = 0.053).”
Quote in the paperSubstantial claim - Findingown data
When decisions were made simultaneously, stronger reliance on tracking α was associated with lower within-group variance.
“when decisions were made simultaneously, the more strongly attacker groups relied on tracking parameter α, the lower their within-group variance when contributing (r = 0.281, p=0.012, Figure 6B)”
Quote in the paperSubstantial claim- Rests on an assumption: Lower within-group variance in contributions indicates better coordination.
- Rests on an assumption: The past defense parameter α captures the rival’s vulnerability.
- Findingown data
Using a dynamic attack-defense contest, oxytocin selectively affects group attacking.
“Using a dynamic attack-defense contest we revealed selective effects of oxytocin on group attacking.”
Quote in the paperSubstantial claim - Findingown data
Oxytocin increased attacker groups' ICC under simultaneous decision-making.
“oxytocin increased attacker groups’ ICC under simultaneous decision-making (t(78) = 2.057, p = 0.043, Cohen’s d = 0.460, Figure 5—figure supplement 1”
Quote in the paperSubstantial claim - Findingown data
Oxytocin increases the number of non-contributors in attacker groups.
“We showed that oxytocin increases the number of non-contributors in attacker groups.”
- Also stated in: § Response time for decisions to (not) contribute · plain
“oxytocin selectively influenced the number of non-contributors in attacker groups.”
Quote in the paperSubstantial claim - Also stated in: § Response time for decisions to (not) contribute · plain
- Findingown data
Oxytocin did not influence defender groups' ICC.
“did not influence defender groups’ ICC (simultaneous: t(78) = 0.485, p = 0.629, Cohen’s d = 0.108; sequential: t(78) = 0.389, p = 0.698, Cohen’s d = 0.087).”
Quote in the paperNot a substantial claim - Findingown data
Multistep mediational analysis showed that the oxytocin effect on increasing attacker group's spoils from winning the conflict plus leftovers from losing the conflict was mediated by its effect on increasing tracking of defenders' history so as to increase within-group coordination.
“multistep mediational analysis showed that the oxytocin effect on increasing attacker group’s spoils from winning the conflict plus leftovers from losing the conflict was mediated by its effect on increasing tracking of defenders’ history so as to increase within-group coordination.”
Quote in the paperSubstantial claim - Findingown data
Under placebo, attackers defeated defenders in 22.08% (SE = 2.2%) of their attacks, which is below the Nash success-rate.
“Attackers defeated defenders in 22.08% (SE = 2.2%) of their attacks, which is below the Nash success-rate (t(39) = −4.734, p < 0.001).”
Quote in the paperNot a substantial claim- The authors state this as an assumption: Participants in the IADC have risk-neutral preferences.
- Findingown data
Oxytocin did not increase attacker groups' ICC under sequential decision-making.
“not under sequential block: t(78) = -0.179, p = 0.859, Cohen’s d = 0.040”
Quote in the paperNot a substantial claim - Findingown data
Defender groups relied more on α to track attacker groups under simultaneous (relative to sequential) decision-making.
“defender groups relied more on α to track attacker groups under simultaneous (relative to sequential) decision-making.”
Quote in the paperNot a substantial claim - Interpretationreasoning
Oxytocin enables individuals to contribute to in-group efficiency and prosperity even when doing so implies outsiders are excluded or harmed.
“subscribe to the possibility that oxytocin enables individuals to contribute to in-group efficiency and prosperity even when doing so implies outsiders are excluded or harmed.”
Quote in the paperSubstantial claim - Interpretationown data
Oxytocin serves as a neurobiological mechanism underlying well-timed and coordinated attacks.
“we uncovered that oxytocin serves as a neurobiological mechanism underlying such well-timed and coordinated attacks.”
Quote in the paperSubstantial claim - Interpretationreasoning
Oxytocin might be a potential neurobiological mechanism through which social bonding and coordinated rituals help groups better coordinate their attacks.
“it suggests that oxytocin might be a potential neurobiological mechanism through which social bonding and performing coordinated rituals can help groups to better coordinate their attacks.”
Quote in the paperSubstantial claim - Interpretationown data
Oxytocin enables groups to coordinate on attacking at the right moment with the right force (rather than a peaceful no-attack strategy).
“Thus, rather than making groups coordinate on a peaceful no-attack strategy, oxytocin may enable groups to coordinate on attacking at the right moment with the right force.”
Quote in the paperSubstantial claim - Interpretationreasoning
Oxytocin-mediated within-group coordination can be substituted by institutional arrangements, such as a sequential decision-making protocol.
“Our findings furthermore suggest that such oxytocin-mediated within-group coordination can be substituted by institutional arrangements, such as a sequential decision-making protocol.”
Quote in the paperSubstantial claim - Interpretationown data
Coordination of contributions is a critical component of successful attacks.
“Our results reveal coordination of contributions as a critical component of successful attacks”
Quote in the paperSubstantial claim - Interpretationreasoning
Exogenous enhancers, whether at the neurobiological or institutional level, appear not necessary for in-group defense coordination.
“Exogenous enhancers, whether at the neurobiological or institutional level, appear not necessary.”
Quote in the paperSubstantial claim - Premisereasoning
Early evidence did not clearly distinguish the distinct motives for contributing to in-group efficiency and out-group hostility.
“did not clearly distinguish the distinct motives for contributing to in-group efficiency and out-group hostility”
Quote in the paperSubstantial claim - Premisecitation
When lacking explicit coordination mechanisms, groups use social norms and focal points to tacitly coordinate collective action.
“when lacking explicit coordination mechanisms such as a leader or decision-making protocols (De Dreu et al., 2016a; Gavrilets and Fortunato, 2014; Hermalin, 1998), groups use social norms and focal points to tacitly coordinate collective action (Halevy and Chou, 2014; Schelling, 1960).”
Quote in the paperSubstantial claim0 of 3 sources checked- cites De Dreu et al., 2016a
Not checked in the free run.
- cites Gavrilets and Fortunato, 2014
Not checked in the free run.
- cites Hermalin, 1998
Not checked in the free run.
- Premisecitation
Out-group attacks frequently fail because individual contributions to out-group attacks are poorly coordinated.
“out-group attacks frequently fail because individual contributions to out-group attacks are poorly coordinated (De Dreu et al., 2016a).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites De Dreu et al., 2016a
Not checked in the free run.
- Premisecitation
Recent work on the role of oxytocin in in-group cooperation suggests similar effects for both male and female participants.
“recent work on the role of oxytocin in in-group cooperation suggests similar effects for both male and female participants (Ten Velden et al., 2017).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Ten Velden et al., 2017 source
Not checked in the free run.
- Premisecitation
Intranasal oxytocin elevates brain-level presence of oxytocin.
“intranasal oxytocin elevates brain-level presence of oxytocin”
Quote in the paperSubstantial claim0 of 3 sources checked - Premisecitation
Intranasal oxytocin modulates neural responses in brain regions involved in threat detection and reward processing.
“intranasal administration of oxytocin has been shown to modulate neural responses in brain regions involved in threat detection and reward processing (Ma et al., 2016b; Paloyelis et al., 2016; Wang et al., 2017; Liu et al., 2019).”
Quote in the paperNot a substantial claim0 of 3 sources checked - Premisereasoning
Early evidence on oxytocin in intergroup interaction was limited to individual-level decision-making.
“Without exception, this early evidence was limited to individual-level decision-making”
Quote in the paperSubstantial claim - Premisecitation
In multi-round intergroup contests, the rival's history of play can serve as a focal point for groups to coordinate their contributions to attack and/or defend.
“In multi-round intergroup contests, the rival’s history of play can serve as a focal point for groups to coordinate their contributions to attack and/or defend (De Dreu et al., 2016b).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites De Dreu et al., 2016b
Not checked in the free run.
- Premisecitation
Intranasal oxytocin impacts behavioral decisions through neural networks involved in threat detection and reward processing.
“impacts behavioral decisions through neural networks involved in threat detection and reward processing”
Quote in the paperNot a substantial claim0 of 3 sources checked - Study design and conductnone given
The study involved only Chinese males as participants.
“First, it involved only Chinese males as study participants.”
Quote in the paperNot a substantial claim - Interpretationown data
In-group coordination for collective action can be tracked to evolutionary preserved neurobiological factors.
“we also obtained first-time evidence that in-group coordination for collective action can be tracked to evolutionary preserved neurobiological factors.”
Quote in the paperSubstantial claim - Premisecitation
Attacking rivals expected to have strong defenses more likely results in failure and waste than attacking groups expected to be weak and defenseless.
“attacking rivals who are expected to have strong defenses more likely results in failure and waste, than attacking groups expected to be weak and defenseless (De Dreu et al., 2016b; Grossman and Kim, 2002; Goeree et al., 2003).”
Quote in the paperNot a substantial claim0 of 3 sources checked - Premisecitation
Small groups preparing for intergroup conflict build cohesion and commitment through social bonding routines and rituals.
“small groups preparing for intergroup conflict build cohesion and commitment through social bonding routines and rituals.”
Quote in the paperSubstantial claim - Premisecitation
The sequential decision-making protocol acts as a coordination device that facilitates behavioral coordination within groups.
“The sequential decision-making protocol acts as a ‘coordination device’ that facilitates behavioral coordination within groups (De Dreu et al., 2016a; Gavrilets and Fortunato, 2014; Hermalin, 1998).”
Quote in the paperSubstantial claim0 of 3 sources checked- cites De Dreu et al., 2016a
Not checked in the free run.
- cites Gavrilets and Fortunato, 2014
Not checked in the free run.
- cites Hermalin, 1998
Not checked in the free run.
- Interpretationown data
The present study provides a new perspective on oxytocin in intergroup conflict by highlighting its functionality for strategic attack rather than defense.
“the present study provides a new perspective on oxytocin in intergroup conflict by highlighting its functionality for strategic attack (rather than defense).”
Quote in the paperSubstantial claim - Premisecitation
The IADC is an all-pay contest with a single mixed-strategy Nash equilibrium.
“The IADC is an all-pay contest with a single mixed-strategy Nash equilibrium (Abbink et al., 2010; Dechenaux et al., 2015).”
Quote in the paperSubstantial claim0 of 2 sources checked
- May combine two claims. 24
- Classified as probably not a substantial claim. 24
May combine two claims.
Findingown dataOxytocin increased the number of non-contributing attackers only in failed rounds, not in successful attacks.
“Oxytocin increased the number of non-contributing attackers only in failed rounds (Oxytocin vs. Placebo: M ± SE = 1.84 ± 0.09 vs. 1.52 ± 0.09; F (1, 74) = 7.036; p = 0.010; η2 = 0.083) but not in successful attacks (Oxytocin vs. Placebo: M ± SE = 0.34 ± 0.06 vs. 0.40 ± 0.06; F (1, 74) = 0.448; p = 0.505; η2 = 0.006).”
Quote in the paperNot a substantial claim- Rests on an assumption: The number of non-contributors reflects strategic refraining from attack.
May combine two claims.
Findingown dataSequential decision-protocol facilitated coordination for attack and reduced coordination for defense.
“sequential decision-protocol facilitated coordination for attack (F(1, 78) = 77.852, p < 0.001, η2 = 0.500) and, unexpectedly, reduced coordination for defense (F(1, 78) = 39.268, p < 0.001, η2 = 0.335).”
Quote in the paperNot a substantial claim- Rests on an assumption: Lower within-group variance in contributions indicates better coordination.
May combine two claims.
Findingown dataOxytocin increased the number of non-contributing members in attacker groups but not in defender groups.
“oxytocin increased the number of non-contributors in attacker groups but not in defender groups (Role × Treatment, F(1, 78) = 5.043, p = 0.028, η2 = 0.061, Figure 3B).”
Quote in the paperSubstantial claim- Rests on an assumption: The number of non-contributors reflects strategic refraining from attack.
May combine two claims.
FindingreasoningNeither oxytocin nor the sequential decision-protocol contributed to within-group coordination in defender groups.
“Neither oxytocin nor the sequential decision-protocol contributed to within-group coordination in defender groups.”
Quote in the paperSubstantial claim- Rests on an assumption: Lower within-group variance in contributions indicates better coordination.
May combine two claims.
Findingown dataOxytocin increased within-group coordination of contributions (reduced within-group variance) in attacker groups, especially in earlier rounds, but not in defender groups.
“over time increased attacker’s within-group coordination of contributions.”
- Also stated in: § Results · plain
“oxytocin facilitated group-level coordination (i.e. reduced within-group variance in contributions) of out-group attack but not of in-group defense, especially in earlier rounds”
- Also stated in: § Discussion · plain
“oxytocin enabled individuals within attacker groups to converge their individual contributions on each other more”
Quote in the paperSubstantial claim- Rests on an assumption: Lower within-group variance in contributions indicates better coordination.
- Also stated in: § Results · plain
May combine two claims.
Findingown dataProviding group members with oxytocin or an explicit coordination device enables them to earn more from their victories.
“and to earn more from their victories.”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataProviding group members with oxytocin or an explicit coordination device enables them to waste less on failed attacks.
“providing group members with oxytocin or an explicit coordination device enables them to waste less on failed attacks”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataThe main effect of Treatment and its interaction with Procedure were not significant for defender groups' tracking of attacker groups.
“The main effect of Treatment and its interaction with Procedure were not significant (ps >0.05).”
Quote in the paperNot a substantial claimClassified as probably not a substantial claim.
Findingown dataThere were very few rounds (9%) in which defenders decided not to contribute.
“there were very few rounds (9%) in which defenders decided not to contribute”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataA Treatment × Role × Procedure ANOVA showed effects for Role, Procedure, and Role x Procedure interaction on ICC.
“A Treatment × Role × Procedure ANOVA showed effects for Role (F(1,78) = 43.090, p < 0.001, η2= 0.356), Procedure (F(1,78) = 166.199, p < 0.001, η2 = 0.681) and for the Role x Procedure interaction (F(1,78) = 147.586, p < 0.001, η2 = 0.654).”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown dataAcross the 15 rounds of simultaneous decision-making under placebo, both out-group attack and in-group defense fell below the Nash equilibrium.
“Across the 15 rounds of simultaneous decision-making under placebo, both out-group attack and in-group defense fell below the Nash-equilibrium (t(39) = −11.30, p < 0.001 and t(39) = −4.18, p < 0.001).”
Quote in the paperNot a substantial claim- The authors state this as an assumption: Participants in the IADC have risk-neutral preferences.
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
Findingown dataThe analysis on β (defense change) failed to show significant main effects of Treatment/Procedure or their interaction.
“the analysis on β failed to show significant main effects of Treatment/Procedure or their interaction (ps >0.1).”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown dataOxytocin did not influence deviations from rationality in attack, defense, or success-rate.
“Oxytocin did not influence deviations from rationality (attack: t(39) = −15.78, p<0.001; defense: t(39) = −6.022, p<0.001; success-rate: t(39) = −6.615, p < 0.001).”
Quote in the paperNot a substantial claim- The authors state this as an assumption: Participants in the IADC have risk-neutral preferences.
Classified as probably not a substantial claim.
InterpretationreasoningIn-group defense is tacitly well-coordinated because of stronger alignment of individual interests within defender groups.
“As a result of this stronger common fate in defender groups, individuals contribute spontaneously and tacitly coordinate well on avoiding collective defeat.”
Quote in the paperSubstantial claimMay combine two claims.
Interpretationown dataGroups given oxytocin created more spoils from winning and had higher leftovers when attacks failed because they better coordinated attack at the right time and with the proper force.
“Combined, results suggest that groups given oxytocin created more spoils from winning and had higher leftovers when attacks failed because they better coordinated attack at the right time and with the proper force.”
Quote in the paperSubstantial claimMay combine two claims.
PremisecitationFindings for the comparison between out-group attack and in-group defense and between sequential and simultaneous decision-making protocols resonate with findings obtained in Western culture, with both male and female participants.
“findings for the comparison between out-group attack and in-group defense and between sequential and simultaneous decision-making protocols resonate with findings obtained in Western culture, with both male and female participants (De Dreu et al., 2016a).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites De Dreu et al., 2016a
Not checked in the free run.
Classified as probably not a substantial claim.
Study design and conductown dataData from 480 participants (80 IADC sessions) were included in the final data analysis.
“Data from 480 participants (80 IADC sessions, age 18–29 years; M ± SE = 20.28±0.09 years) were included in the final data analysis.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationA 24 IU dosage is the most commonly used dosage in oxytocin literature.
“A 24 IU dosage is the most commonly used dosage in oxytocin literature (Wang et al., 2017)”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Wang et al., 2017 source
Not checked in the free run.
Classified as probably not a substantial claim.
Study design and conductcitationThe IADC game was fully incentivized.
“We examined these possibilities using a dynamic, fully incentivized Intergroup Attacker-Defender Contest game (De Dreu et al., 2016a).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites De Dreu et al., 2016a
Not checked in the free run.
May combine two claims.
InterpretationcitationCurrent findings may generalize across cultural contexts and apply to male as well as female participants.
“we cautiously conclude that current findings may generalize across cultural contexts and apply to male as well as female participants.”
Quote in the paperSubstantial claimMay combine two claims.
PremisecitationOxytocin shifts focus from self-interest to in-group interests, limits trust and cooperation to in-group members, and promotes aggression toward threatening rivals.
“oxytocin shifts the focus from self-interest to in-group interests (De Dreu and Kret, 2016), limits trust and cooperation to in-group members (De Dreu et al., 2010; Ma et al., 2015; Ten Velden et al., 2017), and promotes aggression toward threatening rivals (Madden and Clutton-Brock, 2011; Samuni et al., 2017; Striepens et al., 2012; Ne'eman et al., 2016).”
Quote in the paperSubstantial claim0 of 3 sources checked- cites De Dreu and Kret, 2016
Not checked in the free run.
- cites De Dreu et al., 2010 source
Not checked in the free run.
- cites Ma et al., 2015
Not checked in the free run.
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationNeuroendocrine studies link social bonding practices to release of oxytocin.
“Neuroendocrine studies (Burkett et al., 2016; Carter, 2014; Ma et al., 2016b; Samuni et al., 2017) have linked these and related practices to the release of oxytocin, a nine-amino acid neuropeptide.”
Quote in the paperNot a substantial claim0 of 3 sources checkedProbably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductnone givenOne IADC session (N = 6) was dropped from data analysis because of technical failure.
“One IADC session (N = 6) was dropped from data analysis because of technical failure.”
Quote in the paperNot a substantial claimClassified as probably not a substantial claim. May combine two claims.
Study design and conductown dataThe study was double-blind and placebo-controlled with N=480 males in 80 sessions (40 oxytocin, 40 placebo).
“In a double-blind placebo-controlled study with N=480 males in an Intergroup Attacker-Defender contest game”
- Also stated in: § Results · plain
“We created 80 IADC sessions (with N = 480 healthy males); in 40 (40) sessions, participants received intranasal oxytocin (matching placebo) (Figure 1).”
Quote in the paperSubstantial claim- Rests on an assumption: Oxytocin and placebo groups were comparable at baseline.
- Also stated in: § Results · plain
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationHigher levels of oxytocin in saliva, blood, or urine relate to intergroup discrimination.
“and intergroup discrimination (Levy et al., 2016).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Levy et al., 2016 source
Not checked in the free run.
May combine two claims.
PremisecitationOut-group attacks are typically less strong, more variable, and less well-coordinated.
“out-group attacks are typically less strong, more variable, and less well-coordinated (De Dreu et al., 2016a)”
Quote in the paperSubstantial claim0 of 1 sources checked- cites De Dreu et al., 2016a
Not checked in the free run.
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationA 24 IU dosage has been shown as having more pronounced effects (compared with 12 or 48 IU dose of oxytocin) on behavioral and neural responses.
“recently shown as having more pronounced effects (compared with 12 or 48 IU dose of oxytocin) on behavioral and neural responses (Spengler et al., 2017).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Spengler et al., 2017 source
Not checked in the free run.
Probably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductnone givenThe order of simultaneous and sequential decision-making blocks was counterbalanced.
“In the other 15-round block (order counterbalanced), individuals within groups made their decisions in sequence”
Quote in the paperNot a substantial claimClassified as probably not a substantial claim.
PremisecitationTo succeed in intergroup competition and conflict, group members need to coordinate within their group the intensity and timing of attacks.
“Thus, to succeed in intergroup competition and conflict, group members not only need to contribute to their group’s competitive strength, but they also need to coordinate within their group the intensity and timing of attacks.”
Quote in the paperSubstantial claimClassified as probably not a substantial claim. May combine two claims.
Interpretationown dataSuccess and survival in times of intergroup competition and conflict depend on the extent to which individuals make personally costly contributions and on their ability to coordinate their contributions when attacking out-groups or defending against threatening out-groups.
“Success and survival in times of intergroup competition and conflict depend on the extent to which individuals make personally costly contributions and, as shown here, on their ability to coordinate their contributions when attacking out-groups, or defending against threatening out-groups.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationHigher levels of oxytocin in saliva, blood, or urine relate to in-group affiliation and cooperation.
“higher levels of oxytocin in saliva, blood, or urine relate to in-group affiliation and cooperation (Madden and Clutton-Brock, 2011; Samuni et al., 2017)”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites Madden and Clutton-Brock, 2011
Not checked in the free run.
- cites Samuni et al., 2017 source
Not checked in the free run.
Classified as probably not a substantial claim.
PremisecitationIndividuals are more strongly motivated to contribute to defend one's own group than to attack out-groups.
“Recent work has showed that individuals are more strongly motivated to contribute to defend one’s own group than to attack out-groups”
Quote in the paperSubstantial claim0 of 1 sources checked- cites De Dreu et al., 2016a
Not checked in the free run.
Classified as probably not a substantial claim.
Study design and conductcitationSample size estimation indicated that 80 6-person groups were needed to detect a significant effect based on an estimated average small-to-medium effect size of oxytocin effect on social behaviors (d = 0.28).
“Based on an estimated average small-to-medium effect size of oxytocin effect on social behaviors (d = 0.28, Walum et al., 2016), 80 6-person groups were needed to detect a significant effect (α = 0.05, β = 0.85, ANOVA: repeated measures, within-between interaction, G-Power, Faul et al., 2009).”
Quote in the paperSubstantial claim0 of 2 sources checkedClassified as probably not a substantial claim.
PremisereasoningIt remained unknown whether and how oxytocin differentially affects attack and defense behavior during intergroup conflict.
“It remained unknown whether and how oxytocin differentially affects attack and defense behavior during intergroup conflict.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationOxytocin can increase the positive view and benign approach of the in-group.
“It can increase the positive view and benign approach of the in-group”
Quote in the paperNot a substantial claim0 of 3 sources checked- cites De Dreu et al., 2010 source
Not checked in the free run.
- cites De Dreu and Kret, 2016
Not checked in the free run.
- cites Ma et al., 2015
Not checked in the free run.
Classified as probably not a substantial claim. May combine two claims.
Study design and conductown dataThe attacker and defender groups under oxytocin or placebo did not differ in demographic information, mood change, and prosocial-related traits.
“The attacker and defender groups under oxytocin or placebo did not differ in demographic information, mood change, and prosocial-related traits (Supplementary file 1, Table 1A and B).”
Quote in the paperSubstantial claimMay combine two claims.
Interpretationown dataBoth institutional arrangements, such as leading-by-example, and neurobiological mechanisms, such as oxytocin, facilitate behavioral coordination and the effective exploitation of out-group rivals.
“Both institutional arrangements, such as leading-by-example, and neurobiological mechanisms, such as oxytocin, facilitate behavioral coordination and the effective exploitation of out-group rivals.”
Quote in the paperSubstantial claimClassified as probably not a substantial claim.
Study design and conductnone givenParticipants were randomly assigned to intranasal administration of oxytocin or placebo in a double-blind placebo-controlled between-subjects design.
“Participants were randomly assigned to the intranasal administration of oxytocin or placebo in a double-blind placebo-controlled between-subjects design (Figure 1).”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationOxytocin has been linked to subtle forms of intergroup discrimination.
“has been linked to subtle forms of intergroup discrimination”
Quote in the paperNot a substantial claim0 of 3 sources checked- cites De Dreu et al., 2010 source
Not checked in the free run.
- cites De Dreu and Kret, 2016
Not checked in the free run.
- cites Ma et al., 2015
Not checked in the free run.
Probably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductreasoningSix participants in the same IADC session were assigned to the same treatment to avoid potential influence of oxytocin to placebo between individuals.
“Six participants in the same IADC session were assigned to the same treatment (oxytocin or placebo), so as to avoid potential influence of oxytocin to placebo between individuals.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductown data0.51% of decisions were excluded because response time exceeded 180 seconds due to network problem.
“The decisions of which the response time exceeded 180 seconds were excluded in final data analysis (0.51% of the decisions, due to network problem during the experiment).”
Quote in the paperNot a substantial claimMay combine two claims.
PremisecitationIn the IADC, attackers should win 32.45% and defenders should survive 67.55% of the contest rounds.
“attackers (defenders) should win (survive) 32.45% (67.55%) of the contest rounds (De Dreu et al., 2016a).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites De Dreu et al., 2016a
Not checked in the free run.
- The authors state this as an assumption: Participants in the IADC have risk-neutral preferences.
May combine two claims.
PremisecitationWith two three-person groups, each member assumed to have risk-neutral preferences and a discretionary resource of e = 20 MU, the IADC game has a unique mixed-strategy Nash equilibrium with out-group attack expected to average 10.15 and in-group defense 9.77 across rounds.
“With two three-person groups, each member assumed to have risk-neutral preferences and having a discretionary resource of e = 20 MU to invest from, the IADC game has unique mixed-strategy Nash equilibrium with out-group attack (in-group defense) expected to average 10.15 (9.77)across rounds”
Quote in the paperSubstantial claim0 of 1 sources checked- cites De Dreu et al., 2016a
Not checked in the free run.
- The authors state this as an assumption: Participants in the IADC have risk-neutral preferences.
The paper relies on this without support.
The IADC game is a valid model of intergroup conflict in humans.
“We examined these possibilities using a dynamic, fully incentivized Intergroup Attacker-Defender Contest game (De Dreu et al., 2016a).”
The paper relies on this without support.
Intranasal oxytocin reaches relevant brain regions and produces the intended neurobiological effects in this study.
“in 40 (40) sessions, participants received intranasal oxytocin (matching placebo)”
The paper relies on this without support.
Lower within-group variance in contributions indicates better coordination.
“We operationalized within-group coordination as behavioral alignment of contribution to the group, indicated by the variance in contributions to group fighting, with lower group-level variance reflecting better coordination.”
The paper relies on this without support.
The past defense parameter α captures the rival’s vulnerability.
“we examined how attacker groups collectively identified when to attack by creating a past defense parameter α (average defender group’s investment in the last two rounds, that is (Dj-1+Dj-2)/2 on round j) and regressed attacker group’s investments onto α (attack increased when defender groups were vulnerable rather than strong, as indicated by α approaching -1).”
The paper relies on this without support.
The number of non-contributors reflects strategic refraining from attack.
“oxytocin increased the number of non-contributors in attacker groups but not in defender groups”
The paper relies on this without support.
The sample of healthy males is representative of humans in intergroup conflict.
“N = 480 healthy males”
The paper relies on this without support.
Oxytocin and placebo groups were comparable at baseline.
“in 40 (40) sessions, participants received intranasal oxytocin (matching placebo)”
The authors state this as an assumption.
Participants in the IADC have risk-neutral preferences.
“each member assumed to have risk-neutral preferences”
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
OT administration promotes motivation to sacrifice outgroup targets and facilitates within-group coordination for successful outgroup attack during economic games.
“OT administration also promotes motivation to sacrifice outgroup targets (De Dreu et al., 2011) and facilitates within-group coordination for successful outgroup attack during economic games (Zhang et al., 2019).”
From A neurobiological association of revenge propensity during intergroup conflict (2020) · cites this paper as Zhang et al., 2019
We conducted sample size estimation using G*Power 3.1 to determine the number of participants sufficient to detect a reliable effect.
“We conducted sample size estimation using G*Power 3.1 52 to determine the number of participants sufficient to detect a reliable effect.”
From Oxytocin modulates social value representations in the amygdala (2019) · cites this paper as [52]
Applying the hypothesis specifically to self-domestication, selected effects could in theory include reduced tendencies for reactive aggression, on the traditional premise that groups in which males competed more aggressively with group members would be less effective at intergroup conflict.
“Applying the hypothesis specifically to the problem of self-domestication, selected effects could in theory include reduced tendencies for reactive aggression, on the traditional premise that groups in which males competed more aggressively with group members would be less effective at intergroup conflict (e.g., Zhang et al., 2019).”
From Hypotheses for the Evolution of Reduced Reactive Aggression in the Context of Human Self-Domestication (2019) · cites this paper as Zhang et al., 2019
Statistics recomputed
Every reported test result, recomputed from its test statistic and degrees of freedom. A result shows as not adding up only once an independent check has confirmed it.
- ConsistentF(1, 78) = 5.109reported p = .027 · recomputed p = .027
“F(1, 78) = 5.109, p = .027”
- ConsistentF(1, 78) = 3.719reported p = .057 · recomputed p = .057
“F(1, 78) = 3.719, p = .057”
- ConsistentF(1, 78) = 287.903reported p < .001 · recomputed p < .001
“F(1, 78) = 287.903, p < .001”
- ConsistentF(14, 65) = 4.529reported p < .001 · recomputed p < .001
“F(14, 65) = 4.529, p < .001”
- ConsistentF(1, 78) = 408.489reported p < .001 · recomputed p < .001
“F(1, 78) = 408.489, p < .001”
- ConsistentF(1, 78) = 4.345reported p = .04 · recomputed p = .040
“F(1,78) = 4.345, p = .040”
- ConsistentF(1, 78) = 5.043reported p = .028 · recomputed p = .028
“F(1, 78) = 5.043, p = .028”
- ConsistentF(1, 78) = 5.712reported p = .019 · recomputed p = .019
“F(1, 78) = 5.712, p = .019”
- ConsistentF(1, 78) = 2.143reported p = .147 · recomputed p = .147
“F(1, 78) = 2.143, p = .147”
- ConsistentF(1, 78) = 137.679reported p < .001 · recomputed p < .001
“F(1, 78) =137.679, p < .001”
- ConsistentF(1, 77) = 4.857reported p = .031 · recomputed p = .031
“F(1, 77) = 4.857, p = .031”
- ConsistentF(1, 78) = 101.978reported p < .001 · recomputed p < .001
“F(1, 78) = 101.978, p < .001”
- ConsistentF(1, 78) = 77.852reported p < .001 · recomputed p < .001
“F(1, 78) = 77.852, p < .001”
- ConsistentF(1, 78) = 39.268reported p < .001 · recomputed p < .001
“F(1, 78) = 39.268, p < .001”
- ConsistentF(14, 1092) = 1.753reported p = .041 · recomputed p = .041
“F(14, 1092) = 1.753, p = .041”
- ConsistentF(1, 78) = 0.572reported p = .452 · recomputed p = .452
“F(1, 78)=0.572, p = .452”
- Consistentt(78) = 2.609reported p = .011 · recomputed p = .011
“t(78) = 2.609, p = .011”
- Consistentt(74) = 1.819reported p = .073 · recomputed p = .073
“t(74) = 1.819, p = .073”
- ConsistentF(1, 74) = 636.941reported p < .001 · recomputed p < .001
“F (1, 74) = 636.941, p < .001”
- ConsistentF(1, 74) = 6.345reported p = .014 · recomputed p = .014
“F (1, 74) = 6.345, p = .014”
- ConsistentF(1, 78) = 8.312reported p = .005 · recomputed p = .005
“F(1, 78) = 8.312, p = .005”
- Consistentt(39) = -11.3reported p < .001 · recomputed p < .001
“t(39) = −11.30, p < .001”
- Consistentt(39) = -4.18reported p < .001 · recomputed p < .001
“t(39) = −4.18, p < .001”
- Consistentt(39) = -4.734reported p < .001 · recomputed p < .001
“t(39) = −4.734, p < .001”
- Consistentt(39) = -15.78reported p < .001 · recomputed p < .001
“t(39) = −15.78, p < .001”
- Consistentt(39) = -6.022reported p < .001 · recomputed p < .001
“t(39) = −6.022, p < .001”
- Consistentt(39) = -6.615reported p < .001 · recomputed p < .001
“t(39) = −6.615, p < .001”
- ConsistentF(1, 78) = 43.09reported p < .001 · recomputed p < .001
“F(1,78) = 43.090, p < .001”
- ConsistentF(1, 78) = 166.199reported p < .001 · recomputed p < .001
“F(1,78) = 166.199, p < .001”
- ConsistentF(1, 78) = 147.586reported p < .001 · recomputed p < .001
“F(1,78) = 147.586, p < .001”
- Consistentt(78) = 2.057reported p = .043 · recomputed p = .043
“t(78) = 2.057, p = .043”
- Consistentt(78) = -0.179reported p = .859 · recomputed p = .858
“t(78) = -0.179, p = .859”
- Consistentt(78) = 0.485reported p = .629 · recomputed p = .629
“t(78) = 0.485, p = .629”
- Consistentt(78) = 0.389reported p = .698 · recomputed p = .698
“t(78) = 0.389, p = .698”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
α is defined as both defense investment and a regression weight
MinorThe results define α as the average of two defense investments, which cannot approach −1 because investments are nonnegative. The methods instead define α as the regression weight for that average; the reported negative α values only make sense under the latter definition.
“creating a past defense parameter α (average defender group’s investment in the last two rounds, that is (Dj-1+Dj-2)/2 on round j) and regressed attacker group’s investments onto α (attack increased when defender groups were vulnerable rather than strong, as indicated by α approaching -1).”
“average level of defense of last rounds (calculated as (Dj-1 +Djj-2)/2, regression weight referred as α).”
Pooled standard error for failed attacks conflicts with subgroup errors
MinorThe reported pooled mean of 1.68 matches the two treatment means, but its SE of 0.60 is incompatible with subgroup SEs of 0.09 for means of 1.84 and 1.52 across the 76 eligible groups. Combining those subgroup estimates would give a pooled SE around 0.07, not 0.60.
“There were more non-contributing attackers when attack failed than succeeded (Failure vs. Success: M ± SE = 1.68 ± 0.60 vs. 0.37 ± 0.05, F (1, 74) = 636.941, p < 0.001; η2 = 0.891).”
“Oxytocin increased the number of non-contributing attackers only in failed rounds (Oxytocin vs. Placebo: M ± SE = 1.84 ± 0.09 vs. 1.52 ± 0.09; F (1, 74) = 7.036; p = 0.010; η2 = 0.083)”
Cites
Statistical power analyses using G∗Power 3.1: tests for correlation and regression analyses
Faul, F., Erdfelder, E., Buchner, A., & Lang, A.-G. (2009) · Behavior Research Methods · doi:10.3758/brm.41.4.1149 · Cited by 37,615 · see citing works
Mediation in experimental and nonexperimental studies: New procedures and recommendations.
Shrout, P. E., & Bolger, N. (2002) · Psychological Methods · doi:10.1037/1082-989x.7.4.422 · Cited by 11,335 · see citing works
Addressing Moderated Mediation Hypotheses: Theory, Methods, and Prescriptions
Preacher, K. J., Rucker, D. D., & Hayes, A. F. (2007) · Multivariate Behavioral Research · doi:10.1080/00273170701341316 · Cited by 9,973 · see citing works
Confidence Limits for the Indirect Effect: Distribution of the Product and Resampling Methods
MacKinnon, D. P., Lockwood, C. M., & Williams, J. (2004) · Multivariate Behavioral Research · doi:10.1207/s15327906mbr3901_4 · Cited by 7,806 · see citing works
Answers to 20 questions about interrater reliability and interrater agreement
LeBreton, J. M., & Senter, J. L. (2008) · Organizational Research Methods · doi:10.1177/1094428106296642 · Cited by 3,608 · see citing works
The Coevolution of Parochial Altruism and War
Choi, J.-K., & Bowles, S. (2007) · Science · doi:10.1126/science.1144237 · Cited by 1,227 · see citing works
Rethinking the Theoretical Foundation of Sociobiology
Wilson, D. S., & Wilson, E. O. (2007) · The Quarterly Review of Biology · doi:10.1086/522809 · Cited by 1,209 · see citing works
The Neuropeptide Oxytocin Regulates Parochial Altruism in Intergroup Conflict Among Humans
De Dreu, C. K. W., Greer, L. L., Handgraaf, M. J. J., Shalvi, S., Van Kleef, G. A., Baas, M., Ten Velden, F. S., Van Dijk, E., & Feith, S. W. W. (2010) · Science · doi:10.1126/science.1189047 · Cited by 1,148 · see citing works
Self-citationOxytocin enhances amygdala-dependent, socially reinforced learning and emotional empathy in humans
Hurlemann, R., Patin, A., Onur, O. A., Cohen, M. X., Baumgartner, T., Metzler, S., Dziobek, I., Gallinat, J., Wagner, M., Maier, W., et al. (2010) · The Journal of Neuroscience · doi:10.1523/jneurosci.5538-09.2010 · Cited by 771 · see citing works
Oxytocin pathways and the evolution of human behavior
Carter, C. S. (2014) · Annual Review of Psychology · doi:10.1146/annurev-psych-010213-115110 · Cited by 714 · see citing works
A survey of experimental research on contests, all-pay auctions and tournaments
Dechenaux, E., Kovenock, D., & Sheremeta, R. M. (2015) · Experimental Economics · doi:10.1007/s10683-014-9421-0 · Cited by 706 · see citing works
Oxytocin-dependent consolation behavior in rodents
Burkett, J. P., Andari, E., Johnson, Z. V., Curry, D. C., de Waal, F. B. M., & Young, L. J. (2016) · Science · doi:10.1126/science.aac4785 · Cited by 692 · see citing works
Intranasal Oxytocin: Myths and Delusions
Leng, G., & Ludwig, M. (2016) · Biological Psychiatry · doi:10.1016/j.biopsych.2015.05.003 · Cited by 615 · cited 1× · see citing works
“Whereas some have questioned whether intranasal administration of oxytocin can have a direct impact on brain and behavior (Leng and Ludwig, 2016), recent studies in rodents (Neumann et al.”
Increased brain and plasma oxytocin after nasal and peripheral administration in rats and mice
Neumann, I. D., Maloumby, R., Beiderbeck, D. I., Lukas, M., & Landgraf, R. (2013) · Psychoneuroendocrinology · doi:10.1016/j.psyneuen.2013.03.003 · Cited by 511 · see citing works
Extreme Rituals Promote Prosociality
Xygalatas, D., Mitkidis, P., Fischer, R., Reddish, P., Skewes, J., Geertz, A. W., Roepstorff, A., & Bulbulia, J. (2013) · Psychological Science · doi:10.1177/0956797612472910 · Cited by 442 · see citing works
Oxytocin selectively improves empathic accuracy
Bartz, J. A., Zaki, J., Bolger, N., Hollander, E., Ludwig, N. N., Kolevzon, A., & Ochsner, K. N. (2010) · Psychological Science · doi:10.1177/0956797610383439 · Cited by 442 · see citing works
Collective Emotions in Conflict Situations: Societal Implications
Bar‐Tal, D., Halperin, E., & de Rivera, J. (2007) · Journal of Social Issues · doi:10.1111/j.1540-4560.2007.00518.x · Cited by 434 · see citing works
Two types of aggression in human evolution.
Wrangham, R. W. (2018) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1713611115 · Cited by 410 · see citing works
Toward an Economic Theory of Leadership: Leading by ExamplePreprint
Hermalin, B. E. (1997) · SSRN Electronic Journal · doi:10.2139/ssrn.15570 · Cited by 367 · see citing works
Halevy, N., Bornstein, G., & Sagiv, L. (2008) · Psychological Science · doi:10.1111/j.1467-9280.2008.02100.x · Cited by 355 · see citing works
Oxytocin enhances the encoding of positive social memories in humans.
Guastella, A. J., Mitchell, P. B., & Mathews, F. (2008) · Biological Psychiatry · doi:10.1016/j.biopsych.2008.02.008 · Cited by 352 · see citing works
Statistical and Methodological Considerations for the Interpretation of Intranasal Oxytocin Studies
Walum, H., Waldman, I. D., & Young, L. J. (2016) · Biological Psychiatry · doi:10.1016/j.biopsych.2015.06.016 · Cited by 345 · see citing works
Rilling, J. K., DeMarco, A. C., Hackett, P. D., Thompson, R., Ditzen, B., Patel, R., & Pagnoni, G. (2012) · Psychoneuroendocrinology · doi:10.1016/j.psyneuen.2011.07.013 · Cited by 303 · see citing works
De Dreu, C. K. W., & Kret, M. E. (2016) · Biological Psychiatry · doi:10.1016/j.biopsych.2015.03.020 · Cited by 297 · see citing works
Self-citationIntergroup conflict and Intra-Group punishment in an experimental contest game
Abbink, K., Brandts, J., Herrmann, B., & Orzen, H. (2010) · American Economic Review · doi:10.1257/aer.100.1.420 · Cited by 264 · see citing works
Risk averse behavior in generalized matching pennies games
Goeree, J. K., Holt, C. A., & Palfrey, T. R. (2003) · Games and Economic Behavior · doi:10.1016/s0899-8256(03)00052-6 · Cited by 258 · see citing works
Oxytocin facilitates protective responses to aversive social stimuli in males
Striepens, N., Scheele, D., Kendrick, K. M., Becker, B., Schäfer, L., Schwalba, K., Reul, J., Maier, W., & Hurlemann, R. (2012) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1208852109 · Cited by 242 · see citing works
Lee, M. R., Scheidweiler, K. B., Diao, X. X., Akhlaghi, F., Cummins, A., Huestis, M. A., Leggio, L., & Averbeck, B. B. (2018) · Molecular Psychiatry · doi:10.1038/mp.2017.27 · Cited by 235 · see citing works
Kinetics and dose dependency of intranasal oxytocin effects on amygdala reactivity
Spengler, F. B., Schultz, J., Scheele, D., Essel, M., Maier, W., Heinrichs, M., & Hurlemann, R. (2017) · Biological Psychiatry · doi:10.1016/j.biopsych.2017.04.015 · Cited by 229 · see citing works
Oxytocin reactivity during intergroup conflict in wild chimpanzees
Samuni, L., Preis, A., Mundry, R., Deschner, T., Crockford, C., & Wittig, R. M. (2017) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1616812114 · Cited by 207 · see citing works
Paloyelis, Y., Doyle, O. M., Zelaya, F. O., Maltezos, S., Williams, S. C., Fotopoulou, A., & Howard, M. A. (2016) · Biological Psychiatry · doi:10.1016/j.biopsych.2014.10.005 · Cited by 187 · see citing works
Cultural transmission and the evolution of cooperative behavior
Boyd, R. T., & Richerson, P. J. (1982) · Human Ecology · doi:10.1007/bf01531189 · Cited by 182 · see citing works
Oxytocin enhances inter-brain synchrony during social coordination in male adults
Mu, Y., Guo, C., & Han, S. (2016) · Social Cognitive and Affective Neuroscience · doi:10.1093/scan/nsw106 · Cited by 177 · see citing works
Rusch, H. (2014) · Proceedings of the Royal Society B Biological Sciences · doi:10.1098/rspb.2014.1539 · Cited by 175 · see citing works
A solution to the collective action problem in between-group conflict with within-group inequality
Sergey Gavrilets, B., & Fortunato, L. (2014) · Nature Communications · doi:10.1038/ncomms4526 · Cited by 168 · see citing works
Grossman, H., & Kim, M. (1995) · doi:10.3386/w5357 · Cited by 154 · see citing works
Stallen, M., Dreu, C. K. W. D., Shalvi, S., Smidts, A., & Sanfey, A. G. (2012) · Psychological Science · doi:10.1177/0956797612446026 · Cited by 152 · see citing works
Madden, J. R., & Clutton-Brock, T. H. (2011) · Proceedings of the Royal Society B: Biological Sciences · doi:10.1098/rspb.2010.1675 · Cited by 144 · see citing works
Ma, Y., Shamay-Tsoory, S., Han, S., & Zink, C. F. (2016) · Trends in Cognitive Sciences · doi:10.1016/j.tics.2015.10.009 · Cited by 131 · see citing works
Self-citationAerosolized oxytocin increases cerebrospinal fluid oxytocin in rhesus macaques
Modi, M. E., Connor-Stroud, F., Landgraf, R., Young, L. J., & Parr, L. A. (2014) · Psychoneuroendocrinology · doi:10.1016/j.psyneuen.2014.02.011 · Cited by 129 · see citing works
In-group defense, out-group aggression, and coordination failures in intergroup conflict
Dreu, C. K. W. D., Gross, J., Méder, Z. Z., Rojek-Giffin, M., Prochazkova, E., Krikeb, J., & Columbus, S. (2016) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1605115113 · Cited by 123 · see citing works
Self-citationIntranasal administration of oxytocin increases human aggressive behavior
Ne'eman, R., Perach-Barzilay, N., Fischer-Shofty, M., Atias, A., & Shamay-Tsoory, S. G. (2016) · Hormones and Behavior · doi:10.1016/j.yhbeh.2016.01.015 · Cited by 121 · cited 2× · see citing works
“, 2017), and promotes aggression toward threatening rivals (Madden and Clutton-Brock, 2011; Samuni et al., 2017; Striepens et al., 2012; Ne’eman et al., 2016).”
BackgroundLethal coalitionary aggression and long-term alliance formation among Yanomamö men
Macfarlan, S. J., Walker, R. S., Flinn, M. V., & Chagnon, N. A. (2014) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1418639111 · Cited by 118 · see citing works
Adolescents growing up amidst intractable conflict attenuate brain response to pain of outgroup
Levy, J., Goldstein, A., Influs, M., Masalha, S., Zagoory-Sharon, O., & Feldman, R. (2016) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1612903113 · Cited by 108 · see citing works
Delivery of oxytocin to the brain for the treatment of autism spectrum disorder by nasal application
Tanaka, A., Furubayashi, T., Arai, M., Inoue, D., Kimura, S., Kiriyama, A., Kusamori, K., Katsumi, H., Yutani, R., Sakane, T., et al. (2018) · Molecular Pharmaceutics · doi:10.1021/acs.molpharmaceut.7b00991 · Cited by 104 · see citing works
Oxytocin modulates social value representations in the amygdala
Liu, Y., Li, S., Lin, W., Li, W., Yan, X., Wang, X., Pan, X., Rutledge, R. B., & Ma, Y. (2019) · Nature Neuroscience · doi:10.1038/s41593-019-0351-1 · Cited by 89 · cited 3× · see citing works
“, 2016) collectively suggest that intranasal oxytocin elevates brain-level presence of oxytocin, and impacts behavioral decisions through neural networks involved in threat detection and reward processing (Carter, 2014; Hurlemann et al., 2010; Ma et al., 2016b; Rilling et al., 2012; Stallen et al., 2012; Wang et al.,…”
Self-citationWang, D., Yan, X., Li, M., & Ma, Y. (2017) · Social Cognitive and Affective Neuroscience · doi:10.1093/scan/nsx085 · Cited by 86 · see citing works
Self-citationFormation of raiding parties for intergroup violence is mediated by social network structure
Glowacki, L., Isakov, A., Wrangham, R. W., McDermott, R., Fowler, J. H., & Christakis, N. A. (2016) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1610961113 · Cited by 83 · see citing works
Pupil-mimicry conditions trust in partners: moderation by oxytocin and group membership
Kret, M. E., & De Dreu, C. K. W. (2017) · Proceedings of the Royal Society B: Biological Sciences · doi:10.1098/rspb.2016.2554 · Cited by 75 · see citing works
When Two Become One: The Role of Oxytocin in Interpersonal Coordination and Cooperation
Arueti, M., Perach-Barzilay, N., Tsoory, M. M., Berger, B., Getter, N., & Shamay-Tsoory, S. G. (2013) · Journal of Cognitive Neuroscience · doi:10.1162/jocn_a_00400 · Cited by 67 · see citing works
Oxytocin promotes intuitive rather than deliberated cooperation with the in-group
Ten Velden, F. S., Daughters, K., & De Dreu, C. K. W. (2017) · Hormones and Behavior · doi:10.1016/j.yhbeh.2016.06.005 · Cited by 66 · see citing works
Self-citationOpposing Oxytocin Effects on Intergroup Cooperative Behavior in Intuitive and Reflective Minds
Ma, Y., Liu, Y., Rand, D. G., Heatherton, T. F., & Han, S. (2015) · Neuropsychopharmacology · doi:10.1038/npp.2015.87 · Cited by 55 · see citing works
Self-citationSniff and mimic–Intranasal oxytocin increases facial mimicry in a sample of men
Korb, S., Malsert, J., Strathearn, L., Vuilleumier, P., & Niedenthal, P. (2016) · Hormones and Behavior · doi:10.1016/j.yhbeh.2016.06.003 · Cited by 54 · see citing works
Distinct oxytocin effects on belief updating in response to desirable and undesirable feedback
Ma, Y., Li, S., Wang, C., Liu, Y., Li, W., Yan, X., Chen, Q., & Han, S. (2016) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1604285113 · Cited by 54 · see citing works
Self-citationRusch, H. (2014) · Human Nature · doi:10.1007/s12110-014-9199-y · Cited by 53 · see citing works
How decisions happen: Focal points and blind spots in interdependent decision making.
Halevy, N., & Chou, E. Y. (2013) · Journal of Personality and Social Psychology · doi:10.1037/a0035351 · Cited by 40 · see citing works
Placebo treatment facilitates social trust and approach behavior
Yan, X., Yong, X., Huang, W., & Ma, Y. (2018) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1800779115 · Cited by 39 · see citing works
Self-citationThe influence of Oxytocin on automatic motor simulation
Coster, L. D., Mueller, S. C., T'Sjoen, G. G., Saedeleer, L. D., & Braß, M. (2014) · Psychoneuroendocrinology · doi:10.1016/j.psyneuen.2014.08.021 · Cited by 37 · see citing works
The Evolutionary Psychology of War: Offense and Defense in the Adapted Mind
Lopez, A. C. (2017) · Evolutionary Psychology · doi:10.1177/1474704917742720 · Cited by 37 · see citing works
The Detrimental Effects of Oxytocin-Induced Conformity on Dishonesty in Competition
Aydogan, G., Jobst, A., D’Ardenne, K., Müller, N., & Kocher, M. G. (2017) · Psychological Science · doi:10.1177/0956797617695100 · Cited by 31 · see citing works
Dreu, C. K. W. D., Kret, M. E., & Sligte, I. G. (2016) · Social Cognitive and Affective Neuroscience · doi:10.1093/scan/nsw045 · Cited by 15 · see citing works
Flagged first, then by citations
Research works printed but not linked: 2
- Davison, 1977, Bootstrap Methods and Their Application (Vol. 1)
- Schelling, 1960, The Strategy of Conflict
Cited by
Sorted by citations
Within-group synchronization in the prefrontal cortex associates with intergroup conflict
Yang, J., Zhang, H., Ni, J., De Dreu, C. K. W., & Ma, Y. (2020) · Nature Neuroscience · doi:10.1038/s41593-020-0630-x · Cited by 161 · see citing works
Self-citationWrangham, R. W. (2019) · Frontiers in Psychology · doi:10.3389/fpsyg.2019.01914 · Cited by 97 · see citing works
Oxytocin modulates social value representations in the amygdala
Liu, Y., Li, S., Lin, W., Li, W., Yan, X., Wang, X., Pan, X., Rutledge, R. B., & Ma, Y. (2019) · Nature Neuroscience · doi:10.1038/s41593-019-0351-1 · Cited by 89 · see citing works
Self-citationA neurobiological association of revenge propensity during intergroup conflict
Han, X., Gelfand, M. J., Wu, B., Zhang, T., Li, W., Gao, T., Pang, C., Wu, T., Zhou, Y., Zhou, S., et al. (2020) · eLife · doi:10.7554/elife.52014 · Cited by 58 · see citing works
- Authors
- Zhang, H., Gross, J., De Dreu, C., & Ma, Y.
- Affiliations
- Beijing Normal University (CN)
- Leiden University (NL)
- Institute of Psychology, Leiden University, Leiden, The Netherlands
- Corresponding author
- Ma, Yina
- Venue
- eLife
- Publisher
- eLife Sciences Publications, Ltd
- Published
- 2019-01-25
- Volume
- 8
- ISSN
- 2050-084X (ISSN-L)
- PMC
- PMC6347450
- OpenAlex
- W2912232064
- Semantic Scholar
- 4cdaa0ef0666626981380f4ad327fabc9476aa89
- Cited by
- 87
- References
- 61
- Citations by year
- 2026: 3 · 2025: 15 · 2024: 11 · 2023: 7 · 2022: 9 · 2021: 17 · 2020: 15 · 2019: 9 · 2018: 1
- FWCI
- 15.70
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- eLife (publishedVersion, cc-by)
- Europe PMC (PubMed Central) (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- Zurich Open Repository and Archive (University of Zurich) (acceptedVersion, cc-by)
- Leiden Repository (Leiden University) (submittedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- University of Groningen research database (University of Groningen / Centre for Information Technology) (submittedVersion, cc-by)
- OSF Preprints (OSF Preprints) (submittedVersion)
- Zurich Open Repository and Archive (University of Zurich) (submittedVersion, cc-by)
- Data Archiving and Networked Services (DANS) (submittedVersion, other-oa)
- Data Archiving and Networked Services (DANS) (submittedVersion, cc-by)
- Zurich Open Repository and Archive (University of Zurich)
- Funders
- National Natural Science Foundation of China (31722026, 31771204, 31661143039, 91632118)
- Fundamental Research Funds for the Central Universities (2018EYT04, 2017XTCX04)
- Spinoza Award from the Netherlands Science Foundation (NWO SPI-57-242)
- Beijing Municipal Science and Technology Commission (Z151100003915122)
- Topics
- Social Sciences › Psychology › Social Psychology › Neuroendocrine regulation and behavior
- Social Sciences › Safety Research › Experimental Behavioral Economics Studies
- Social Sciences › Sociology and Political Science › Evolutionary Game Theory and Cooperation
- Keywords
- oxytocin, intergroup conflict, in-group cooperation, aggression, social exclusion
- MeSH terms
- Adolescent, Adult, Conflict, Psychological, Decision Making, Humans, Interpersonal Relations, Male, Oxytocin, Reaction Time, Young Adult
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.
Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
