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Oxytocin Effect on Collective Decision Making: A Randomized Placebo Controlled Study.

Hertz U, Kelly M, Rutledge RB, Winston J, Wright N, Dolan RJ, Bahrami B - PLoS ONE (2016)

Bottom Line: Collective decision making often benefits both the individuals and the group in a variety of contexts.Compared to placebo, collective benefit did not decrease under oxytocin.Using an exploratory time dependent analysis, we observed increase in collective benefit over time under oxytocin.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, WC1N 3AR, United Kingdom.

ABSTRACT
Collective decision making often benefits both the individuals and the group in a variety of contexts. However, for the group to be successful, individuals should be able to strike a balance between their level of competence and their influence on the collective decisions. The hormone oxytocin has been shown to promote trust, conformism and attention to social cues. We wondered if this hormone may increase participants' (unwarranted) reliance on their partners' opinion, resulting in a reduction in collective benefit by disturbing the balance between influence and competence. To test this hypothesis we employed a randomized double-blind placebo-controlled design in which male dyads self-administered intranasal oxytocin or placebo and then performed a visual search task together. Compared to placebo, collective benefit did not decrease under oxytocin. Using an exploratory time dependent analysis, we observed increase in collective benefit over time under oxytocin. Moreover, trial-by-trial analysis showed that under oxytocin the more competent member of each dyad was less likely to change his mind during disagreements, while the less competent member showed a greater willingness to change his mind and conform to the opinion of his more reliable partner. This role-dependent effect may be mediated by enhanced monitoring of own and other's performance level under oxytocin. Such enhanced social learning could improve the balance between influence and competence and lead to efficient and beneficial collaboration.

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Oxytocin effect on egocentric bias collective benefit.(A) When announcing the joint decision participants could keep their original choice or go with the other member’s decision. We used ANCOVA model to estimate the relation between total number of joint decisions made by a participant and the number of egocentric (agree with self) joint decisions. This relationship is captured by the slope and intercept estimated by the ANCOVA model: steeper slope indicates an egocentric inclination, i.e. tendency to not change one’s mind during disagreements. We did not find a significant treatment effect, and no difference in slopes between worse and better members. (B) We fitted psychometric curves to the data from the entire experiment duration, estimating the dyadic sensitivity and the individual sensitivities of dyad members (sDyad, sMax, sMin). Collective benefit is the difference between the dyadic sensitivity and the better dyad member (Sdyad-Smax). Under oxytocin dyads’ collective benefit was significantly higher than 0 (p = 0.026), but not under placebo (p = 0.2). However, collective benefit was not significantly different between oxytocin and placebo.
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pone.0153352.g003: Oxytocin effect on egocentric bias collective benefit.(A) When announcing the joint decision participants could keep their original choice or go with the other member’s decision. We used ANCOVA model to estimate the relation between total number of joint decisions made by a participant and the number of egocentric (agree with self) joint decisions. This relationship is captured by the slope and intercept estimated by the ANCOVA model: steeper slope indicates an egocentric inclination, i.e. tendency to not change one’s mind during disagreements. We did not find a significant treatment effect, and no difference in slopes between worse and better members. (B) We fitted psychometric curves to the data from the entire experiment duration, estimating the dyadic sensitivity and the individual sensitivities of dyad members (sDyad, sMax, sMin). Collective benefit is the difference between the dyadic sensitivity and the better dyad member (Sdyad-Smax). Under oxytocin dyads’ collective benefit was significantly higher than 0 (p = 0.026), but not under placebo (p = 0.2). However, collective benefit was not significantly different between oxytocin and placebo.

Mentions: We hypothesised that oxytocin may have an effect on the participants’ willingness to change their minds during disagreements. On average, oxytocin dyads performed 310 ± 37 (mean ± std) trials and placebo dyads performed 314 ± 16 (p = 0.67) trials. Number of disagreements for oxytocin and placebo dyads were 112 ± 22, and 117 ± 17 respectively (p = 0.5). Each participant declared the dyad’s joint decisions in approximately half of the disagreement trials (keyboard participants: 57 ± 9.45; mouse participants 57.83 ± 12.2 times; paired t-test p = 0.55). When declaring the joint decisions participants could adhere to their original choice or switch to the other dyad member’s decision. We examined the relation between the number of times participant kept their original view and the overall number of joint decisions they arbitrated. We used analysis of covariance (ANCOVA) where the numbers of egocentric decisions (keeping one’s original decision) during disagreements were the dependent variable, and the total number of joint decisions declared by the participant served as covariates. The main effects were treatment (oxytocin/placebo) and role (better/worse member). ANCOVA analysis therefore fitted linear models between dependent variables and covariates under each condition, and compared the slopes between conditions. Steeper slopes indicated egocentric decisions; tendency to not change one’s mind during disagreement. The slopes were not significantly different across treatments, not for better members (F(1,39) = 0.29, p = 0.59), and not for worse members (F(1,39) = 0.05, p = 0.82), and not between better and worse participants (F(1,82) = 0.3, p = 0.58) (Fig 3A). Oxytocin did not induce overall change in allocentric/egocentric bias.


Oxytocin Effect on Collective Decision Making: A Randomized Placebo Controlled Study.

Hertz U, Kelly M, Rutledge RB, Winston J, Wright N, Dolan RJ, Bahrami B - PLoS ONE (2016)

Oxytocin effect on egocentric bias collective benefit.(A) When announcing the joint decision participants could keep their original choice or go with the other member’s decision. We used ANCOVA model to estimate the relation between total number of joint decisions made by a participant and the number of egocentric (agree with self) joint decisions. This relationship is captured by the slope and intercept estimated by the ANCOVA model: steeper slope indicates an egocentric inclination, i.e. tendency to not change one’s mind during disagreements. We did not find a significant treatment effect, and no difference in slopes between worse and better members. (B) We fitted psychometric curves to the data from the entire experiment duration, estimating the dyadic sensitivity and the individual sensitivities of dyad members (sDyad, sMax, sMin). Collective benefit is the difference between the dyadic sensitivity and the better dyad member (Sdyad-Smax). Under oxytocin dyads’ collective benefit was significantly higher than 0 (p = 0.026), but not under placebo (p = 0.2). However, collective benefit was not significantly different between oxytocin and placebo.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829266&req=5

pone.0153352.g003: Oxytocin effect on egocentric bias collective benefit.(A) When announcing the joint decision participants could keep their original choice or go with the other member’s decision. We used ANCOVA model to estimate the relation between total number of joint decisions made by a participant and the number of egocentric (agree with self) joint decisions. This relationship is captured by the slope and intercept estimated by the ANCOVA model: steeper slope indicates an egocentric inclination, i.e. tendency to not change one’s mind during disagreements. We did not find a significant treatment effect, and no difference in slopes between worse and better members. (B) We fitted psychometric curves to the data from the entire experiment duration, estimating the dyadic sensitivity and the individual sensitivities of dyad members (sDyad, sMax, sMin). Collective benefit is the difference between the dyadic sensitivity and the better dyad member (Sdyad-Smax). Under oxytocin dyads’ collective benefit was significantly higher than 0 (p = 0.026), but not under placebo (p = 0.2). However, collective benefit was not significantly different between oxytocin and placebo.
Mentions: We hypothesised that oxytocin may have an effect on the participants’ willingness to change their minds during disagreements. On average, oxytocin dyads performed 310 ± 37 (mean ± std) trials and placebo dyads performed 314 ± 16 (p = 0.67) trials. Number of disagreements for oxytocin and placebo dyads were 112 ± 22, and 117 ± 17 respectively (p = 0.5). Each participant declared the dyad’s joint decisions in approximately half of the disagreement trials (keyboard participants: 57 ± 9.45; mouse participants 57.83 ± 12.2 times; paired t-test p = 0.55). When declaring the joint decisions participants could adhere to their original choice or switch to the other dyad member’s decision. We examined the relation between the number of times participant kept their original view and the overall number of joint decisions they arbitrated. We used analysis of covariance (ANCOVA) where the numbers of egocentric decisions (keeping one’s original decision) during disagreements were the dependent variable, and the total number of joint decisions declared by the participant served as covariates. The main effects were treatment (oxytocin/placebo) and role (better/worse member). ANCOVA analysis therefore fitted linear models between dependent variables and covariates under each condition, and compared the slopes between conditions. Steeper slopes indicated egocentric decisions; tendency to not change one’s mind during disagreement. The slopes were not significantly different across treatments, not for better members (F(1,39) = 0.29, p = 0.59), and not for worse members (F(1,39) = 0.05, p = 0.82), and not between better and worse participants (F(1,82) = 0.3, p = 0.58) (Fig 3A). Oxytocin did not induce overall change in allocentric/egocentric bias.

Bottom Line: Collective decision making often benefits both the individuals and the group in a variety of contexts.Compared to placebo, collective benefit did not decrease under oxytocin.Using an exploratory time dependent analysis, we observed increase in collective benefit over time under oxytocin.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, WC1N 3AR, United Kingdom.

ABSTRACT
Collective decision making often benefits both the individuals and the group in a variety of contexts. However, for the group to be successful, individuals should be able to strike a balance between their level of competence and their influence on the collective decisions. The hormone oxytocin has been shown to promote trust, conformism and attention to social cues. We wondered if this hormone may increase participants' (unwarranted) reliance on their partners' opinion, resulting in a reduction in collective benefit by disturbing the balance between influence and competence. To test this hypothesis we employed a randomized double-blind placebo-controlled design in which male dyads self-administered intranasal oxytocin or placebo and then performed a visual search task together. Compared to placebo, collective benefit did not decrease under oxytocin. Using an exploratory time dependent analysis, we observed increase in collective benefit over time under oxytocin. Moreover, trial-by-trial analysis showed that under oxytocin the more competent member of each dyad was less likely to change his mind during disagreements, while the less competent member showed a greater willingness to change his mind and conform to the opinion of his more reliable partner. This role-dependent effect may be mediated by enhanced monitoring of own and other's performance level under oxytocin. Such enhanced social learning could improve the balance between influence and competence and lead to efficient and beneficial collaboration.

Show MeSH