Unravelling the role of oxytocin in behavioural flexibility

• Deilhaug, Elisabeth; Moerkerke, Matthijs; Sartorius, Alina I.; Kang, Heemin; Bull, Emilie Meyer & Walle, Kjersti M. [Show all 11 contributors for this article] (2026). Using EEG to Measure the Neural Effects of Oxytocin Administration: A Meta‐Analysis and Systematic Review. Psychophysiology. ISSN 0048-5772. 63(6). doi: 10.1111/psyp.70334. Full text in Research Archive Show summary

  Electroencephalography (EEG) has emerged as a key method for investigating the neural mechanisms through which oxytocin influences cognition and behavior. EEG is cost‐effective, has excellent temporal precision, and may elucidate neural correlates of emotional and cognitive processes. EEG studies evaluating oxytocin's electrophysiological effects have, however, yielded mixed results, which is likely driven by heterogeneity in EEG measures, study designs, dosages, and samples. To investigate the effect of oxytocin administration on EEG measures, we performed two multilevel random effects meta‐analyses: The first meta‐analysis synthesized studies investigating the effects of oxytocin administration on different neural correlates of social and cognitive processing; the second meta‐analysis synthesized studies evaluating effects of oxytocin administration on exploratory, less task‐specific neural activity measures, such as the modulation of microstates. Across both meta‐analyses, we synthesized 161 effect sizes from 28 randomized controlled trials with a total of 1361 participants from different population groups. These multilevel meta‐analyses yielded statistically significant, small effect sizes of oxytocin administration across different EEG measures reflecting social and cognitive processes (Hedges' g  = 0.14), and exploratory neural activity (Hedges' g  = 0.28) with significant heterogeneity estimates ( p  < 0.01 and p  < 0.001, respectively). Moderator analyses revealed that the different EEG measurements of interest (e.g., event‐related potentials) and the proportion of female participants were found to significantly moderate the effect of oxytocin on neural EEG activity. Altogether, these meta‐analyses present tentative evidence for oxytocin administration modulating a wide range of EEG‐based markers of neural activity. We observed substantial heterogeneity across studies—in terms of study designs, experimental paradigms and EEG measurements, and participant characteristics. More research is warranted to map out the context‐specific effects of oxytocin administration on different neural markers, to better understand the neurobiological mechanisms of oxytocin.

• Glaser, Bernt Damian; Kang, Heemin; Audunsdottir, Kristin; Sartorius, Alina Marie & Quintana, Daniel (2026). A tutorial for calculating field-specific effect size distributions. Behavior Research Methods. ISSN 1554-351X. 58(6). doi: 10.3758/s13428-026-03003-2. Full text in Research Archive Show summary

  Effect sizes are useful for understanding the magnitude of study results and for planning new studies via power analysis. However, despite their wide usage, effect sizes are often misinterpreted. This is mostly due to an over-reliance on general effect size benchmarks that were not intended for broad application across diverse research fields. Inaccurate effect size interpretations can lead to incorrect conclusions about the magnitude of study results and incorrect sample size estimates, thereby increasing the likelihood of false-positive results. This article introduces the ESDist R package, which is designed to calculate empirically derived effect-size benchmarks or a range of reliably detectable empirical effect sizes for a specific research question or field of interest by computing effect size distributions (ESDs). This package can be used on data that can be easily extracted from pre-existing meta-analyses to help researchers more accurately plan new studies or to better understand how an individual study might relate to other studies in their field. ESDist includes a set of features that make it easy to use in a priori power analysis. Moreover, the package includes a feature for estimating effect size benchmarks that account for publication bias and are weighted by effect sizes' variances, which addresses existing limitations of using ESDs for study planning or interpretation.

• Walle, Kjersti Mæhlum; Sartorius, Alina I.; Deilhaug, Elisabeth; Kang, Heemin; Nærland, Terje & Andreassen, Ole [Show all 8 contributors for this article] (2026). Reframing oxytocin as a behavioral flexibility hormone. Neuroscience and Biobehavioral Reviews. ISSN 0149-7634. 185. doi: 10.1016/j.neubiorev.2026.106628. Full text in Research Archive
• Schubert, Anna-Lena; Steinhilber, Meike; Kang, Heemin & Quintana, Daniel (2025). Improving statistical reporting in psychology. Communications Psychology. 3(1). doi: 10.1038/s44271-025-00356-w. Full text in Research Archive Show summary

  Transparent and comprehensive statistical reporting is critical for ensuring the credibility, reproducibility, and interpretability of psychological research. This paper offers a structured set of guidelines for reporting statistical analyses in quantitative psychology, emphasizing clarity at both the planning and results stages. Drawing on established recommendations and emerging best practices, we outline key decisions related to hypothesis formulation, sample size justification, preregistration, outlier and missing data handling, statistical model specification, and the interpretation of inferential outcomes. We address considerations across frequentist and Bayesian frameworks and fixed as well as sequential research designs, including guidance on effect size reporting, equivalence testing, and the appropriate treatment of null results. To facilitate implementation of these recommendations, we provide the Transparent Statistical Reporting in Psychology (TSRP) Checklist that researchers can use to systematically evaluate and improve their statistical reporting practices ( https://osf.io/t2zpq/ ). In addition, we provide a curated list of freely available tools, packages, and functions that researchers can use to implement transparent reporting practices in their own analyses to bridge the gap between theory and practice. To illustrate the practical application of these principles, we provide a side-by-side comparison of insufficient versus best-practice reporting using a hypothetical cognitive psychology study. By adopting transparent reporting standards, researchers can improve the robustness of individual studies and facilitate cumulative scientific progress through more reliable meta-analyses and research syntheses.

• Iversen, Ingebjørg A.; Alaerts, Kaat; Bakermans-Kranenburg, Marian; Becker, Benjamin; Blair, Robert James & Bartz, Jennifer A. [Show all 24 contributors for this article] (2025). The active monitoring of oxytocin research evidence (AMORE) platform. Psychoneuroendocrinology. ISSN 0306-4530. 185, p. 1–12. doi: 10.1016/j.psyneuen.2025.107713. Full text in Research Archive Show summary

  Oxytocin, an evolutionarily conserved neuropeptide, plays a crucial role in various physiological and behavioural processes, offering potential therapeutic benefits for several psychiatric and neurodevelopmental conditions. Despite its promise, oxytocin research has been marked by inconsistent results concerning its therapeutic applications and underlying mechanisms. Performing a systematic review and meta-analysis is a popular approach to shed light on mixed findings in a body of literature; however, they can become quickly outdated as new evidence becomes available. Given these challenges, research on the links between oxytocin and biobehavioural outcomes is ideally positioned for the adoption of ‘living’ meta-analyses, which allow for the continuous integration of new data and updated conclusions. Here we introduce the Active Monitoring of Oxytocin Research Evidence (AMORE) platform (https://amore-project.org), which is a hub that aggregates articles and materials associated with living meta-analyses for biobehavioural oxytocin research in humans. Developed through consensus among 24 expert researchers, a standardized framework was established that either requires or recommends practices ensuring transparency and rigor in living meta-analyses featured on the AMORE platform. Overall, AMORE has been designed to advance human oxytocin biobehavioural research by the timely integration of emerging evidence through transparent living meta-analyses. To date, two living meta-analysis projects at different stages of publication are hosted on AMORE, demonstrating the platform’s practical application.

• Kang, Heemin; Deilhaug, Elisabeth; Walle, Kjersti Mæhlum; Sartorius, Alina Marie & Quintana, Daniel S. (2025). A multiverse meta-analysis of oxytocin administration studies. Biological Psychology. ISSN 0301-0511. 201, p. 1–10. doi: 10.1016/j.biopsycho.2025.109112. Full text in Research Archive Show summary

  Oxytocin administration is a valuable approach for experimentally increasing central oxytocin levels to investigate its impact on brain function and behavior. Despite considerable research interest, results have shown considerable variability across studies. Several meta-analyses have been conducted to help address this inconsistency. However, conducting a meta-analysis requires researchers to make numerous decisions, such as defining inclusion criteria and analytical techniques. In response to this challenge, a ‘multiverse’ approach can be used to simultaneously explore a range of different potential and realistic scenarios by systematically varying these analytical decisions. In this study, we performed a multiverse meta-analysis to investigate how researcher decisions can influence outcomes in meta-analyses of oxytocin administration studies. We systematically varied inclusion criteria, data synthesis models, and methods for correcting publication bias across 530 effect sizes derived from 185 studies, conducting 256 distinct meta-analyses. Our results demonstrate that summary effect estimates can vary considerably depending on meta-analytic decisions (from d = −0.16 to d = 1.45). Notably, meta-analyses with neurotypical populations tended to yield larger effect sizes than non-neurotypical populations, and multiple administrations studies tended to yield larger effect sizes than single administration studies. Furthermore, summary effect estimates can substantially vary according to the applied publication bias correction method. Our findings also demonstrated that the current evidence mostly supports the presence of the effect of oxytocin across domains, regardless of meta-analytic choices, as over 90% of the observed meta-analyses exceeded the range of bootstrapped meta-analyses assuming a null effect. These results warrant future research on how different contexts may impact the robustness of the effects of oxytocin, while underscoring the value of meta-analysis pre-registration to facilitate the transparent evaluation of meta-analyst decision-making.

• Roettger, Timo; Askelund, Jo Adrian Dahl; Birkenæs, Viktoria; Bjørndal, Ludvig Daae; Bochynska, Agata & Glaser, Bernt Damian [Show all 13 contributors for this article] (2025). Transparency in epidemiological analyses of cohort data a case study of the Norwegian mother, father, and child cohort study (MoBa). BMC Medical Research Methodology. 25, p. 1–11. doi: 10.1186/s12874-025-02601-6. Full text in Research Archive Show summary

  Background Epidemiological research is central to our understanding of health and disease. Secondary analysis of cohort data is an important tool in epidemiological research but is vulnerable to practices that can reduce the validity and robustness of results. As such, adopting measures to increase the transparency and reproducibility of secondary data analysis is paramount to ensuring the robustness and usefulness of findings. The uptake of such practices has not yet been systematically assessed. Methods Using the Norwegian Mother, Father, and Child Cohort study (MoBa; [23, 24]) as a case study, we assessed the prevalence of the following reproducible practices in publications between 2007–2023: preregistering secondary analyses, sharing of synthetic data, additional materials, and analysis scripts, conducting robustness checks, directly replicating previously published studies, declaring conflicts of interest and publishing publicly available versions of the paper. Results Preregistering secondary data analysis was only found in 0.4% of articles. No articles used synthetic data sets. Sharing practices of additional data (2.3%), additional materials (3.4%) and analysis scripts (4.2%) were rare. Several practices, including data and analysis sharing, preregistration and robustness checks became more frequent over time. Based on these assessments, we present a practical example for how researchers might improve transparency and reproducibility of their research. Conclusions The present assessment demonstrates that some reproducible practices are more common than others, with some practices being virtually absent. In line with a broader shift towards open science, we observed an increasing use of reproducible research practices in recent years. Nonetheless, the large amount of analytical flexibility offered by cohorts such as MoBa places additional responsibility on researchers to adopt such practices with urgency, to both ensure the robustness of their findings and earn the confidence of those using them. A particular focus in future efforts should be put on practices that help mitigating bias due to researcher degrees of freedom – namely, preregistration, transparent sharing of analysis scripts, and robustness checks. We demonstrate by example that challenges in implementing reproducible research practices in analysis of secondary cohort data—even including those associated with data sharing—can be meaningfully overcome.

• Kang, Heemin; Glaser, Bernt Damian; Sartorius, Alina Marie; Audunsdottir, Kristin; Bull, Emilie Meyer & Nærland, Terje [Show all 9 contributors for this article] (2025). Effects of oxytocin administration on non-social executive functions in humans: A preregistered systematic review and meta-analysis. Molecular Psychiatry. ISSN 1359-4184. doi: 10.1038/s41380-024-02871-4. Full text in Research Archive
• Audunsdottir, Kristin; Sartorius, Alina Marie; Kang, Heemin; Glaser, Bernt Damian; Bøen, Rune & Nærland, Terje [Show all 11 contributors for this article] (2024). The effects of oxytocin administration on social and routinized behaviors in autism: A preregistered systematic review and meta-analysis. Psychoneuroendocrinology. ISSN 0306-4530. 167. doi: 10.1016/j.psyneuen.2024.107067. Full text in Research Archive Show summary

  Oxytocin administration has demonstrated considerable promise for providing individualized support for autistic people. However, studies evaluating the effects of oxytocin administration on autistic characteristics have yielded inconsistent results. This systematic review and meta-analysis investigates the effect of oxytocin administration on social and routinized behaviors in autism using recently developed methods to accurately assess the potential impact of effect size dependency and publication bias. Our frequentist meta-analysis yielded a significant summary effect size estimate for the impact of oxytocin administration on social outcomes in autism (d = 0.22, p < 0.001). The summary effect size estimate for routinized behavior outcomes was not statistically significant (d = 0.14, p = 0.22), with a follow up test indicating that the effect size estimate was not either statistically equivalent (Z = −1.06, p = 0.2), assuming a smallest effect size of interest of 0.25. Frequentist and Bayesian assessments for publication bias, as well as results from Robust Bayesian meta-analysis of oxytocin effects on social outcomes in autism, indicated that summary effect sizes might be inflated due to publication bias. Future studies should aim to reduce bias by preregistering analysis plans and to increase precision with larger sample sizes.

• Quintana, Daniel; Glaser, Bernt Damian; Kang, Heemin; Bull, Emilie Meyer; Audunsdottir, Kristin & Sartorius, Alina Marie [Show all 7 contributors for this article] (2024). The interplay of oxytocin and sex hormones. Neuroscience and Biobehavioral Reviews. ISSN 0149-7634. 163, p. 1–18. doi: 10.1016/j.neubiorev.2024.105765. Full text in Research Archive Show summary

  The neuropeptide oxytocin has historically been associated with reproduction and maternal behavior. However, more recent research has uncovered that oxytocin has a much wider range of roles in physiology and behavior. Despite the excitement surrounding potential therapeutical applications of intranasally administered oxytocin, the results of these intervention studies have been inconsistent. Various reasons for these mixed results have been proposed, which tend to focus on methodological issues, such as study design. While methodological issues are certainly important, emerging evidence suggests that the interaction between oxytocin and sex hormones may also account for these varied findings. To better understand the purpose and function of the interaction of oxytocin with sex hormones, with a focus on estrogens, progesterone, and testosterone, we conducted a comprehensive thematic review via four perspectives: evolutionary, developmental, mechanistic, and survival. Altogether, this synergistic approach highlights the critical function of sex hormone activity for accomplishing the diverse roles of oxytocin via the modulation of oxytocin release and oxytocin receptor activity, which is also likely to contribute to the heterogeneity of outcomes after oxytocin administration.

• Quintana, Daniel (2023). A Guide for Calculating Study-Level Statistical Power for Meta-Analyses. Advances in Methods and Practices in Psychological Science (AMPPS). ISSN 2515-2459. 6(1). doi: 10.1177/25152459221147260. Full text in Research Archive
• Jongerius, Chiara; Hillen, Marij A.; Smets, Ellen M. A.; Mol, Mathijs J.; Kooij, Eefje S. & Nood, Maria A. de [Show all 10 contributors for this article] (2023). Nasal oxytocin administration does not influence eye gaze or perceived relationship of male volunteers with physicians in a simulated online consultation: a randomized, placebo-controlled trial. Endocrine Connections. 12(8). doi: 10.1530/EC-22-0377. Full text in Research Archive Show summary

  The patient–physician relationship is a critical determinant of patient health outcomes. Verbal and non-verbal communication, such as eye gaze, are vital aspects of this bond. Neurobiological studies indicate that oxytocin may serve as a link between increased eye gaze and social bonding. Therefore, oxytocin signaling could serve as a key factor influencing eye gaze as well as the patient–physician relationship. We aimed to test the effects of oxytocin on gaze to the eyes of the physician and the patient–physician relationship by conducting a randomized placebo-controlled crossover trial in healthy volunteers with intranasally administered oxytocin (with a previously effective single dose of 24 IU, EudraCT number 2018-004081-34). The eye gaze of 68 male volunteers was studied using eye tracking during a simulated video call consultation with a physician, who provided information about vaccination against the human papillomavirus. Relationship outcomes, including trust, satisfaction, and perceived physician communication style, were measured using questionnaires and corrected for possible confounds (social anxiety and attachment orientation). Additional secondary outcome measures for the effect of oxytocin were recall of information and pupil diameter and exploratory outcomes included mood and anxiety measures. Oxytocin did not affect the eye-tracking parameters of volunteers’ gaze toward the eyes of the physician. Moreover, oxytocin did not affect the parameters of bonding between volunteers and the physician nor other secondary and exploratory outcomes in this setting. Bayesian hypothesis testing provided evidence for the absence of effects. These results contradict the notion that oxytocin affects eye gaze patterns or bonding.

• Melby, Katrine; Spigset, Olav; Gråwe, Rolf W.; Aamo, Trond Oskar & Quintana, Daniel (2022). The effect of intranasal oxytocin on processing emotional stimuli during alcohol withdrawal: A randomized placebo-controlled double-blind clinical trial. Hormones and Behavior. ISSN 0018-506X. 146. doi: 10.1016/j.yhbeh.2022.105268. Full text in Research Archive Show summary

  Alcohol dependence is associated with difficulties in processing emotional stimuli, which can lead to interpersonal problems. The neuropeptide oxytocin has been shown to modulate the processing of emotional stimuli, however, oxytocin treatment has not yet been examined in patients with withdrawal symptoms during alcohol detoxification. The aim of the present study was to investigate the effect of oxytocin on the reading the mind in the eyes test (RMET), which indexes theory of mind ability, during a three-day period of alcohol detoxification at an addiction treatment centre in Norway. We performed a randomized, double-blind, placebo-controlled trial in 39 patients fulfilling criteria for ICD-10 diagnosis of alcohol dependence admitted for alcohol detoxification and withdrawal treatment. Participants were randomized to receive either intranasal oxytocin (24 IU) or placebo, twice daily for three days. We evaluated RMET performance on day 2 and day 3 of detoxification and differences in RMET scores between day 2 and day 3 of detoxification. Frequentist and Bayesian statistical inference suggested that oxytocin administration during alcohol withdrawal in alcohol-dependent patients did not improve RMET performance. However, exploratory analyses provided preliminary evidence that oxytocin might improve performance on the RMET negative emotion subscale (uncorrected p value = 0.038), and that oxytocin treatment might show the most promise for those with high levels of alcohol consumption (i.e., ≥20 alcohol units per day; uncorrected p value = 0.023). Moreover, alcohol consumption levels significantly predicted RMET performance on day 2, but not on day 3, of withdrawal.

• Winterton, Adriano; Bettella, Francesco; Beck, Dani; Gurholt, Tiril Pedersen; Steen, Nils Eiel & Rødevand, Linn Nilsen [Show all 9 contributors for this article] (2022). The oxytocin signalling gene pathway contributes to the association between loneliness and cardiometabolic health. Psychoneuroendocrinology. ISSN 0306-4530. 144. doi: 10.1016/j.psyneuen.2022.105875. Full text in Research Archive Show summary

  Increasing evidence has shown adverse effects of loneliness on cardiometabolic health. The neuromodulator and hormone oxytocin has traditionally been linked with social cognition and behaviour. However, recent implications of the oxytocin system in energy metabolism and the overrepresentation of metabolic issues in psychiatric illness suggests that oxytocin may represent a mechanism bridging mental and somatic traits. To clarify the role of the oxytocin signalling system in the link between cardiometabolic risk factors and loneliness, we calculated the contribution of single nucleotide polymorphisms (SNPs) in the oxytocin signalling pathway gene-set (154 genes) to the polygenic architecture of loneliness and body mass index (BMI). We investigated the associations of these oxytocin signalling pathway polygenic scores with body composition measured using body magnetic resonance imaging (MRI), bone mineral density (BMD), haematological markers, and blood pressure in a sample of just under half a million adults from the UK Biobank (BMD subsample n = 274,457; body MRI subsample n = 9796). Our analysis revealed significant associations of the oxytocin signalling pathway polygenic score for BMI with abdominal subcutaneous fat tissue, HDL cholesterol, lipoprotein(a), triglycerides, and BMD. We also found an association between the oxytocin signalling pathway polygenic score for loneliness and apolipoprotein A1, the major protein component of HDL. Altogether, these results provide additional evidence for the oxytocin signalling pathway’s role in energy metabolism, lipid homoeostasis, and bone density, and support oxytocin’s complex pleiotropic effects.

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• Quintana, Daniel (2022). Oxytocin’s role in health and wellbeing. Full text in Research Archive
• Quintana, Daniel (2022). Accelerating the translation of intranasal oxytocin research. Full text in Research Archive

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