Encountering a newcomer attenuates shared evaluative standards: experimental evidence of rapid emergence and partial persistence

Collective activity requires individuals to converge on common yardsticks for judging the world; however, it remains unclear how these evaluative standards (ES) respond when a group encounters unfamiliar members. Using a newly developed dot-estimation task informed by Sherif’s classic norm-formation studies, this study experimentally tracked (a) how shared ES emerge through dyadic interactions and (b) how they respond to a newcomer whose judgements systematically diverge. Participants first completed rounds with a partner whose estimates gradually aligned with their own, with perceptual bias shifting reliably toward that partner’s standard within a single block of thirty trials.

However, when a newcomer with divergent estimates entered, participants partially shifted toward the newcomer’s standard, while their responses suggested carryover from the prior interaction. Impressions of the divergent newcomer did not depend on whether participants had previously established a shared standard with another partner, indicating that brief behavioural alignment does not by itself generate derogation of a divergent other. Taken together, these findings show that shared ES form quickly through dyadic interaction and, although attenuated by exposure to a newcomer, persist in part within individuals.

Understanding the micro-dynamics of their formation and partial persistence helps explain how groups negotiate common standards and how those standards may attenuate—without fully unravelling—when group composition changes. This study was supported by the Japan Society for the Promotion of Science (JSPS KAKENHI Grant Number JP23K18991, JP24K16800, and JP26H00368 to MY). We thank Editage (http://www.editage.jp/) for English language editing.

This work was supported by JSPS KAKENHI Grant Number JP23K18991, JP24K16800, and JP26H00368. Present address: Graduate School of Human Sciences, The University of Osaka, Suita, Osaka, Japan Faculty of Culture and Information Science, Doshisha University, Kyotanabe, Japan Faculty of Science and Engineering, Otemon Gakuin University, Ibaraki, Japan The authors declare no competing interests. This study was approved by the Ethics Committee of Doshisha University (Approval No. 23027) on 22 September 2023, and was conducted in accordance with the Committee’s guidelines and regulations.

Informed consent was obtained from all participants during the period 30 November 2023 to 31 January 2024. Before the task, trained experimenters orally explained the study purpose, procedures, and ethical considerations, after which participants provided their written, hand-signed consent. Because the study involved deception (participants were told that the person invited to the same session was their task partner), a full debriefing was conducted at the end of the experiment.

Participants were then asked to reconfirm their consent for the use of their data following the disclosure that their partner had actually been a bot. All consent procedures adhered to institutional ethical standards. Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.