A registered replication study on oxytocin and trust

May combine two claims.

The six studies that failed to replicate the Kosfeld et al. findings were not direct replications; they did not use the same methods and procedures as the original study.

“These studies were, however, not direct replications, i. e., they did not use the same methods and procedures as the original study.”

Classified as probably not a substantial claim.

Money transfers in the trust game indicate that investors are willing to tolerate a certain level of uncertainty.

“Money transfers in the trust game indicate that investors are willing to tolerate a certain level of uncertainty.”

May combine two claims.

The Kosfeld et al. study suggested that oxytocin increased trusting decisions in the trust game but did not augment risk-taking in an identically framed risk game played against a computer.

“The Kosfeld et al. study 8 already suggested this: OT increased trusting decisions in the trust game, but did not augment risk-taking in an identically framed risk game played against a computer.”

• cites [8] Kosfeld, M., Heinrichs, M., Zak, P. J., Fischbacher, U. & Fehr, E. Oxytocin increases trust in humans. Nature 435, 673–676 (2005). sourceNot checked yet

  Not checked in the free run.

May combine two claims.

In humans, oxytocin can alleviate social stress by lowering salivary cortisol levels, increasing parasympathetic control of the heart, and attenuating amygdala activation in response to seeing faces.

“In humans, OT is mostly known for its functions in childbirth and breastfeeding, but it can also alleviate social stress, for example, by lowering salivary cortisol levels 4 , increasing parasympathetic control of the heart 5 , and attenuating amygdala activation in response to seeing faces 6,7 .”

• cites [4] Heinrichs, M., Baumgartner, T., Kirschbaum, C. & Ehlert, U. Social support and oxytocin interact to suppress cortisol and subjective responses to psychosocial stress. Biol. Psychiatry 54, 1389–1398 (2003). sourceNot checked yet

  Not checked in the free run.

• cites [5] Norman, G. J. et al. Oxytocin increases autonomic cardiac control: moderation by loneliness. Biol. Psychol. 86, 174–180 (2011). sourceNot checked yet

  Not checked in the free run.

• cites [6] Kirsch, P. Oxytocin modulates neural circuitry for social cognition and fear in humans. J. Neurosci. 25, 11489–11493 (2005). sourceNot checked yet

  Not checked in the free run.

• cites [7] Lambert, B., Declerck, C. H., Boone, C. & Parizel, P. M. A functional MRI study on how oxytocin affects decision making in social dilemmas: cooperate as long as it pays off, aggress only when you think you can win. Horm. Behav. 94, 145–152 (2017). sourceNot checked yet

  Not checked in the free run.

Classified as probably not a substantial claim.

Administering a single dose of intranasal oxytocin compared to placebo increases the willingness to trust in a dyadic economic game with real monetary stakes.

“This question has sparked more than a decade of research ever since the first report that administering a single dose of intranasal OT (compared to placebo) increases the willingness to trust in a dyadic economic game with real monetary stakes 8 .”

• cites [8] Kosfeld, M., Heinrichs, M., Zak, P. J., Fischbacher, U. & Fehr, E. Oxytocin increases trust in humans. Nature 435, 673–676 (2005). sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).

Other critics have pointed out that there is no overarching theory to explain the diverse findings resulting from intranasal oxytocin administration.

“Other critics have pointed out that there is no overarching theory to explain the diverse findings resulting from intranasal OT administration 20 .”

• cites [20] Churchland, P. S. & Winkielman, P. Modulating social behavior with oxytocin: how does it work? What does it mean? Horm. Behav. 61, 392–399 (2012). sourceNot checked yet

  Not checked in the free run.

Classified as probably not a substantial claim.

The effect of oxytocin in humans is expected to be limited to social situations where initiating or establishing partnership is important to realize synergy.

“Because animal research has documented that OT is primarily a social bonding hormone that activates socio-emotional neural pathways in the brain 22,23 , we would also expect the effect of OT in humans to be limited to social situations where initiating or establishing partnership is important to realize synergy.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The worry that another person may not reciprocate influences transfers beyond the perceived riskiness of the game, and betrayal aversion inhibits investors' trust.

“Interestingly, the worry that another person may not reciprocate appears to influence transfers beyond the perceived riskiness of the game 9,10 , i.e., it is not just the risk of losing money but the fear of being cheated (i.e., betrayal aversion) that inhibits the investors' trust.”

• cites [9] Bohnet, I., Greig, F., Herrmann, B. & Zeckhauser, R. Betrayal aversion: evidence from Brazil, China, Oman, Switzerland, Turkey, and the United States. Am. Econ. Rev. 98, 294–310 (2008). sourceNot checked yet

  Not checked in the free run.

• cites [10] Fehr, E. On the economics and biology of trust. J. Eur. Econ. Assoc. 7, 235–266 (2009). sourceNot checked yet

  Not checked in the free run.

Classified as probably not a substantial claim. May combine two claims.

Nave and colleagues have raised doubt on the robustness of the oxytocin-trust association, pointing out that six studies failed to replicate the initial findings reported by Kosfeld et al.

“More specifically, Nave and colleagues 21 have raised doubt on the robustness of the oxytocin-trust association, pointing out that six studies failed to replicate the initial findings reported by Kosfeld et al. 8 .”

• cites [21] Nave, G., Camerer, C. & McCullough, M. Does oxytocin increase trust in humans? A critical review of research. Perspect. Psychol. Sci. 10, 772–789 (2015). sourceNot checked yet

  Not checked in the free run.

• cites Kosfeld et al. 8Not checked yet

  Not checked in the free run.

May combine two claims.

Animal research has documented that oxytocin is primarily a social bonding hormone that activates socio-emotional neural pathways in the brain.

“Because animal research has documented that OT is primarily a social bonding hormone that activates socio-emotional neural pathways in the brain 22,23 , we would also expect the effect of OT in humans to be limited to social situations where initiating or establishing partnership is important to realize synergy.”

• cites [22] Ross, H. E. & Young, L. J. Oxytocin and the neural mechanisms regulating social cognition and affiliative behavior. Front. Neuroendocrinol. 30, 534–547 (2009). sourceNot checked yet

  Not checked in the free run.

• cites [23] Young, L. J. & Wang, Z. The neurobiology of pair bonding. Nat. Neurosci. 7, 1048–1054 (2004). sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Oxytocin is a neuropeptide with a central role in regulating social approach and attachment behaviors in many non-human mammals.

“To learn more about the biological basis of trust, researchers have investigated the potential causal link with the hormone oxytocin (OT), a neuropeptide with a central role in regulating social approach and attachment behaviors in many non-human mammals [1][2][3] .”

• cites [1][2][3]Not checked yet

  Not checked in the free run.

Classified as probably not a substantial claim. May combine two claims.

Kosfeld et al. (2005) showed that intranasal administration of oxytocin increases the transfers made by investors in the trust game, suggesting that oxytocin increases trust in strangers.

“In an influential paper, Kosfeld et al. (2005) showed that intranasal administration of Oxytocin (OT) increases the transfers made by investors in the trust game -suggesting that OT increases trust in strangers.”

• cites Kosfeld et al. (2005) sourceNot checked yet

  Not checked in the free run.

May combine two claims.

Minimal social contact is the cue that enhances the prosocial approach potential of oxytocin and reduces social apprehension, thereby enhancing trust in an environment where approach behavior is a precondition for a mutually advantageous exchange.

“We propose that minimal social contact is the cue that enhances the prosocial approach potential of OT and reduces social apprehension, thereby enhancing trust in an environment where approach behavior is a precondition for a mutually advantageous exchange.”

Classified as probably not a substantial claim.

Kosfeld et al. reported an η2 = 0.071 for the global difference between all four experimental groups under consideration.

“To bolster their results, Kosfeld et al. 8 assessed the global difference between all four experimental groups under consideration (trust/Placebo, trust/OT, risk/Placebo, and risk/OT) to ensure a family-wise error of α = 5%.The reported findings correspond to an η² = 0.071 (r = 0.267).”

• cites Kosfeld et al. 8Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S2 (checkable).

Despite the enormous resonance of the Kosfeld et al. study, the minimal social contact feature of the study has often been overlooked or neglected.

“Despite the enormous resonance of the Kosfeld 8 et al. study, the minimal social contact feature of the study has often been overlooked or neglected.”

Classified as probably not a substantial claim.

Participants in the trust game had some minimal social face-to-face contact with each other in groups prior to playing the game against someone whose exact identity would not be revealed.

“To enhance the saliency of the social context, participants in the trust game had some minimal social (faceto-face) contact with each other in groups prior to playing the game against someone whose exact identity would not be revealed.”

Classified as probably not a substantial claim. May combine two claims.

The proposed study will overcome the drawbacks of non-parametric testing because it will recruit a large sample that will enable the use of OLS regression techniques.

“Our study will overcome these drawbacks because we will recruit a large sample that will enable us to use OLS regression techniques.”

Classified as probably not a substantial claim.

By boosting the dopaminergic signal in the mesolimbic network, oxytocin is thought to enhance the salience of social cues that emphasize the value of approach behavior.

“By boosting the dopaminergic signal in the mesolimbic network, OT is thought to enhance the salience of social cues that emphasize the value of approach behavior 7,35,36 .”

• cites [7] Lambert, B., Declerck, C. H., Boone, C. & Parizel, P. M. A functional MRI study on how oxytocin affects decision making in social dilemmas: cooperate as long as it pays off, aggress only when you think you can win. Horm. Behav. 94, 145–152 (2017). sourceNot checked yet

  Not checked in the free run.

• cites [35] Love, T. M. Oxytocin, motivation and the role of dopamine. Pharmacol. Biochem. Behav. 119, 49–60 (2014). sourceNot checked yet

  Not checked in the free run.

• cites [36] Shamay‐Tsoory, S. G. & Abu‐Akel, A. The social salience hypothesis of oxytocin. Biol. Psychiatry 79, 194–202 (2016). sourceNot checked yet

  Not checked in the free run.

Classified as probably not a substantial claim.

Social contact had to be minimal to avoid elevating trust to a level beyond which no further increase could reasonably be expected after oxytocin administration.

“Importantly, the social contact had to be minimal to avoid elevating trust to a level beyond which no further increase could reasonably be expected after OT administration.”

May combine two claims.

In that study, intranasal oxytocin significantly increased coordination on the mutually beneficial alternative strategy, but only if participants first had the opportunity to introduce themselves to the whole group of participants from which one was randomly drawn to become the partner.

“It turned out that intranasal OT significantly increased coordination on the mutually beneficial alternative strategy, but only if participants first had the opportunity to introduce themselves to the whole group of participants from which one was randomly drawn to become the partner.”

• cites [31] Declerck, C. H., Boone, C. & Kiyonari, T. Oxytocin and cooperation under conditions of uncertainty: the modulating role of incentives and social information. Horm. Behav. 57, 368–374 (2010). sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Social contact was not intense enough to cause strong feelings of social familiarity, as this might generate a ceiling effect in trust.

“(ii) Social contact was not intense enough to cause strong feelings of social familiarity, as this might also generate a ceiling effect in trust.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Increasing evidence suggests that oxytocin's function is not always consistent with facilitating social approach, but that administering intranasal oxytocin can also lead to parochial, competitive, and envious behaviors and behaviors that appear to be driven by schadenfreude, which have an anti-social dimension.

“Since the publication of this study, increasing evidence suggests that OT's function is not always consistent with facilitating social approach, but that administering intranasal OT can also lead to parochial, competitive, and envious behaviors and behaviors that appear to be driven by schadenfreude 16,17,32 , which have an anti-social dimension.”

• cites [16] De Dreu, C. K. W. Oxytocin modulates cooperation within and competition between groups: an integrative review and research agenda. Horm. Behav. 61, 419–428 (2012). sourceNot checked yet

  Not checked in the free run.

• cites [17] De Dreu, C. K. W. & Kret, M. E. Oxytocin conditions intergroup relations through upregulated in group empathy, cooperation, conformity, and defense. Biol. Psychiatry 79, 165–173 (2016). sourceNot checked yet

  Not checked in the free run.

• cites [32] Shamay-Tsoory, S. G. et al. Intranasal administration of oxytocin increases envy and schadenfreude (gloating). Biol. Psychiatry 66, 864–870 (2009). sourceNot checked yet

  Not checked in the free run.

Classified as probably not a substantial claim.

The tests described in (ii) and (iii) in the Kosfeld study are about comparisons between a trust and a risk game, which differ substantially from the current design that does not have a risk game.

“Note, however, that the tests described in (ii) and (iii) in the Kosfeld study 8 are about comparisons between a trust and a risk game, which differ substantially from the current design which does not have a risk game (i.e., a game played against a computer).”

• cites Kosfeld study 8Not checked yet

  Not checked in the free run.

May combine two claims.

The a priori power analysis is based on the effect size d = 0.514 reported in test (i) of Kosfeld et al. and the requirement of a one-tailed test, which is justified when testing a directional hypothesis.

“We base our a priori power analysis on the effect size d = 0.514, reported in test (i) of Kosfeld et al. 8 and the requirement of a one-tailed test, which is justified when testing a directional 38 hypothesis.”

• cites Kosfeld et al. 8Not checked yet

  Not checked in the free run.

• cites [38] Aron, A., Aron, E. N. & Smollan, D. Inclusion of other in the self scale and the structure of interpersonal closeness. J. Pers. Soc. Psychol. 63, 596–612 (1992). sourceNot checked yet

  Not checked in the free run.

May combine two claims.

According to the a priori power analysis and robustness check, a sample size of n = 704 will provide statistical power of more than 95% for all main hypotheses and exceeds the sample size recommendations of Nave et al.

“According to the a priori power analysis presented in detail below and the robustness check reported in Supplementary Information 1 and 2, a sample size of n = 704 will provide a statistical power of more than 95% for all main hypotheses and also exceeds the sample size recommendations of Nave et al.21 .”

• cites Nave et al.21 Nave, G., Camerer, C. & McCullough, M. Does oxytocin increase trust in humans? A critical review of research. Perspect. Psychol. Sci. 10, 772–789 (2015). sourceNot checked yet

  Not checked in the free run.

May combine two claims.

Of the six studies in Nave et al.'s meta-analysis, four had fictional partners, one was completely devoid of human contact with other participants, and the sixth had participants' previous experience in a dictator game likely to confound the decision to trust.

“Of the six studies that entered the meta-analysis in Nave et al.21 -in addition to the Kosfeld 8 et al. study -four studies had fictional partners [25][26][27][28] , one was completely devoid of human contact with other participants 29 , and participants' previous experience in a dictator game was likely to confound the decision to trust in the sixth study 30 .”

• cites [25][26][27][28]Not checked yet

  Not checked in the free run.

• cites [29] Baumgartner, T., Heinrichs, M., Vonlanthen, A., Fischbacher, U. & Fehr, E. Oxytocin shapes the neural circuitry of trust and trust adaptation in humans. Neuron 58, 639–650 (2008). sourceNot checked yet

  Not checked in the free run.

• cites [30] Barraza, J. A. The physiology of empathy: linking oxytocin to empathic responding. Diss. Abstr. Int. Sect. B Sci. Eng. 71, 4537 (2011).Not checked yet

  Not checked in the free run.

May combine two claims.

Kosfeld et al. were forced to use non-parametric tests because their sample did not comply with assumptions made in parametric tests, and the smallest sample size in testing was n = 29.

“Kosfeld et al. 8 were forced to use non-parametric tests in their study because their sample did not comply with assumptions made in parametric tests.Specifically, the smallest sample size in testing (i)-(iii) was n=29.”

• cites Kosfeld et al. 8Not checked yet

  Not checked in the free run.

Classified as probably not a substantial claim. May combine two claims.

A current leading theory rests on neurological evidence that oxytocin modulates mesolimbic dopaminergic neurons, thereby affecting both incentive motivation and attention re-orienting.

“A current leading theory to account for why OT can stimulate both prosocial and anti-social behaviors rests on neurological evidence that OT modulates mesolimbic dopaminergic neurons, thereby affecting both incentive motivation as well as attention re-orienting.”

• cites [7] Lambert, B., Declerck, C. H., Boone, C. & Parizel, P. M. A functional MRI study on how oxytocin affects decision making in social dilemmas: cooperate as long as it pays off, aggress only when you think you can win. Horm. Behav. 94, 145–152 (2017). sourceNot checked yet

  Not checked in the free run.

• cites [35] Love, T. M. Oxytocin, motivation and the role of dopamine. Pharmacol. Biochem. Behav. 119, 49–60 (2014). sourceNot checked yet

  Not checked in the free run.

• cites [36] Shamay‐Tsoory, S. G. & Abu‐Akel, A. The social salience hypothesis of oxytocin. Biol. Psychiatry 79, 194–202 (2016). sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The proposed study will be carried out with the approval of the Medical Ethics Commissions of the Universities of Antwerp and Magdeburg.

“The proposed study will be carried out with the approval of the Medical Ethics Commissions of the Universities of Antwerp and Magdeburg.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Information about compliance behaviors is deliberately collected immediately after the experiment, after participants have been paid, so that they have no incentive to lie.

“We deliberately collect information about these behaviors immediately after the experiment (i.e., after participants have been paid) so that they have no incentive to lie.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Adding generalized trust and general risk attitude as covariates will reduce standard errors in treatment estimates and correct for potential imbalances from imperfect randomization.

“Adding these two covariates will also reduce the standard errors in our treatment estimates -thus allowing sharper estimates -and correct for potential imbalances in the samples that occur through imperfect randomization.”

Probably not a substantial claim: may not pass S4 (based).

The stratification ensures that the distribution of individuals' social value orientations will be the same in each treatment condition.

“This stratification ensures that the distribution of individuals' SVOs will be the same in each treatment condition.”

Classified as probably not a substantial claim.

A final inclusion criterion is participants' understanding of the trust game instructions, checked by requiring both hypothetical payoff examples to be solved correctly.

“A final criterion is participants' understanding of the trust game instructions.We will check this by letting them compute the monetary payoffs for both players in two hypothetical examples of the trust game.Both examples need to be solved correctly to be included in the data analyses.”

May combine two claims.

Measuring trust with a single decision rather than averaging several consecutive decisions prevents hedge betting and may encourage intuitive thinking, which is the decision-making type oxytocin is most likely to influence.

“Measuring trust with a single decision (rather than averaging several consecutive decisions) has the advantage that it prevents hedge betting and may thus encourage intuitive thinking, which is the decision making type OT is most likely to influence, 7,47 rather than complicated deliberation.”

• cites [7] Lambert, B., Declerck, C. H., Boone, C. & Parizel, P. M. A functional MRI study on how oxytocin affects decision making in social dilemmas: cooperate as long as it pays off, aggress only when you think you can win. Horm. Behav. 94, 145–152 (2017). sourceNot checked yet

  Not checked in the free run.

• cites [47] MacDonald, K. S. Sex, receptors, and attachment: a review of individual factors influencing response to oxytocin. Front. Neurosci. 6, 194 (2013). sourceNot checked yet

  Not checked in the free run.

May combine two claims. The quote only partly states this claim.

Using d = 0.32, the required total sample size for 80% power is 244 (122 per group), with actual power 0.802.

“Total sample size 244 Actual Power 0.802”

Classified as probably not a substantial claim. May combine two claims.

Social value orientation is a relatively stable personality feature describing a person's intrinsic willingness to behave prosocially, and it has been found to predict trusting decisions and sensitivity to social cues.

“SVO is a relatively stable personality feature describing a person's intrinsic willingness to behave prosocially 48 , that has been found to predict trusting decisions 49 and sensitivity to social cues 50 .”

• cites [48] Van Zijl., F. V. W., Timman, R. & Datema, F. R. Adaptation and validation of the Dutch version of the nasal obstruction symptom evaluation (NOSE) scale. Eur. Arch. Otorhinolary. 274, 2469–2476 (2017). sourceNot checked yet

  Not checked in the free run.

• cites [49] Lipan, M. J. & Most, S. P. Development of a severity classification system for subjective nasal obstruction. JAMA Facial Plast. Surg. 15, 358–361 (2013). sourceNot checked yet

  Not checked in the free run.

• cites [50] Teixeira, R. U. F., Zappelini, C. E. M., Oliveira, L. G., Basile, L. C. G. & Costa, E. A. Correlation between the peak nasal inspiratory flow and the visual analogue scale (VAS) before and after using a nasal decongestant. Int. Arch. Otorhinolary. 15, 156–162 (2011).Not checked yet

  Not checked in the free run.

Classified as probably not a substantial claim.

Such inter-individual differences might introduce excessive noise in the data which could obscure the results.

“Such inter-individual differences might introduce excessive noise in the data which could obscure the results.”

Classified as probably not a substantial claim. May combine two claims.

Participants will be randomly assigned to one of the four treatment conditions, but randomization will be stratified based on participants' social value orientation measured two weeks prior to the experiment.

“Participants will be randomly assigned to one of the four treatment conditions (no contact/Placebo, no contact/OT, minimal social contact/Placebo, minimal social contact/OT) but randomization will be stratified based on participants' social value orientation (SVO) which will be measured during registration two weeks prior to the experiment with an online survey.”

The quote only partly states this claim.

The effect size required for the Kosfeld et al. study to have 33% power is d = 0.320.

“Effect size d 0.320”

• cites Kosfeld et al. 3Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

To guarantee anonymity, participants' names will be replaced by a self-made, retrievable code through which they can be identified during the remainder of the study.

“To guarantee anonymity, their names will from then on be replaced by a self-made, retrievable code through which they can be identified during the remainder of the study.”

Classified as probably not a substantial claim. May combine two claims.

Oxytocin/placebo administration will be double blind following a randomized block design, with a block corresponding to a session.

“OT/placebo administration will be double blind following a randomized block design (with a block corresponding to a session).”

Classified as probably not a substantial claim.

Social value orientation is controlled for via stratified randomization.

“We do not plan to include social value orientation 48 as a covariate because we control for SVO via stratified randomization.”

May combine two claims.

The main motivation for the study is to replicate the Kosfeld et al. study, which was conducted only with males.

“First, the main motivation for the study is to replicate the Kosfeld et al. 8 study, which was conducted only with males.”

• cites Kosfeld et al. 8Not checked yet

  Not checked in the free run.

Classified as probably not a substantial claim.

A recent study reports that a dose of 24 IU oxytocin is more effective in triggering an amygdala response and eliciting fear reduction compared to either lower 12 IU or higher 48 IU doses.

“A recent study investigating the dose dependency of oxytocin reports that a dose of 24 IU OT is more effective in triggering an amygdala response and eliciting fear reduction compared to either lower (12 IU) or higher (48 IU) doses 51 , although this contradicts an earlier study in which 8 IU was found to be the most effective 52 .”

• cites [51] Hsu, H. C. et al. Evaluation of nasal patency by visual analogue scale/nasal obstruction symptom evaluation questionnaires and anterior active rhinomanometry after septoplasty: a retrospective one-year follow-up cohort study. Clin. Otolaryngol. 42, 53–59 (2016). sourceNot checked yet

  Not checked in the free run.

Classified as probably not a substantial claim. May combine two claims.

If participants are rated as non-compliant with the rules for self-administration or the self-administration is judged as problematic by the supervisor, the participant is ruled out from data analysis.

“If participants are rated as non-compliant with the rules for self-administration (category 5) or the self-administration is judged as problematic by the supervisor (category 4) the participant is ruled out from data analysis.”

May combine two claims.

Sex-specific gonadal steroids influence oxytocin-receptor binding in the brain, and intranasal oxytocin can affect the behavior of males and females differently, even in opposite directions.

“Second, we know from the previous literature that sex-specific gonadal steroids influence OT-receptor binding in the brain, and that intranasal oxytocin can affect the behavior of males and females differently, even in opposite directions 40 .”

• cites [40] Berg, J., Dickhaut, J. & McCabe, K. Trust, reciprocity and social history. Games Econ. Behav. 10, 122–142 (1995). sourceNot checked yet

  Not checked in the free run.

May combine two claims.

An earlier study found 8 IU to be the most effective, but that study used a Breath Powered device for oxytocin administration which is likely to have increased absorption significantly.

“The latter study, however, made use of a Breath Powered device for OT administration which is likely to have increased absorption significantly.”

• cites [52] Ten Velden, F. S., Daughters, K. & De Dreu, C. K. W. Oxytocin promotes intuitive rather than deliberated cooperation with the in‐group. Horm. Behav. 92, 164–171 (2017). sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

The trust and risk measures will serve as control variables when testing the primary a priori hypotheses.

“The trust and risk measures will serve as control variables when testing the primary (a priori) hypotheses (described in the next section), while the other variables will serve as moderators in further exploratory analyses.”

Classified as probably not a substantial claim. May combine two claims.

The post-experimental questionnaire queries participants' beliefs about treatment received (OT vs placebo), allowing testing for a placebo effect.

“Importantly, this questionnaire will query participants' beliefs regarding the treatment they received (OT versus placebo) which allows us to test the possibility of a placeboeffect.”

The quote only partly states this claim.

A priori sample size computation using G*Power with effect size d = 0.514, power 0.95, yields 83 participants per group (actual power 0.951).

“Actual power 0.951”

• cites G*Power 3.1.9.2 28Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Guiding participants immediately to their cubicles upon arrival (sessions 6-11) minimizes contact with other participants before the experiment and increases control over subjects' social contacts.

“In sessions 6-11, participants were guided immediately to their cubicles upon arrival.This minimizes the contact with other participants before the experiment and increases our control over subjects social contacts.”

Probably not a substantial claim: may not pass S3 (load-bearing).

In Social 2, the complete lack of verbal interaction caused a strange and awkward situation that was associated with reduced investments.

“This complete lack of verbal interaction caused a strange and akward situation that was associated with reduced investments.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Questions assessing feelings of connectedness can be used to test whether the minimal social contact and no contact conditions differed in this respect.

“Finally, a number of questions assess participants' feelings of connectedness with others, which can be used to test if the minimal social contact and no contact condition differed in this respect.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Filling out the MDMS questionnaire a second time enables checking for mood changes following nasal spray administration.

“They will also fill out the MDMS questionnaire for a second time.This will enable us to check for mood changes following nasal spray administration.”