Babies Judge Sharing Differently Depending on Whose Shoes They Stand In

Long before babies utter their first words, they are already watching how people treat one another—and, according to new research, their verdicts depend on where they are standing. A study published in Frontiers in Developmental Psychology reports that eleven-month-old infants evaluate sharing behavior differently depending on the perspective they adopt, offering some of the clearest evidence yet that the roots of moral judgment are far more context-sensitive than researchers once assumed.

The study, conducted by Zijian Tian and Kazuo Hiraki of the University of Tokyo, set out to answer a deceptively simple question: does a baby’s assessment of an act of sharing change depending on whether the baby is judging from the viewpoint of the person giving, the person receiving, or a neutral bystander? Decades of research have shown that preverbal infants prefer helpers over hinderers, fair distributors over unfair ones, and protectors over aggressors. But those findings typically tested infants as third-party observers watching scripted puppet shows. The Tokyo team suspected that when the moral stakes are personal—when the evaluator is imagined to be a participant in the interaction itself—the picture might look very different.

To find out, the researchers built an animated scenario around a swing. One agent, the initial possessor, arrives first and claims the swing, riding it upward with sparkling sound effects that mark the experience as rewarding. A second agent, a newcomer, then appears and jumps repeatedly while facing the swing and maintaining eye contact with its occupant—a behavior designed to signal a request for a turn. In the Sharing condition, the occupant dismounts and trades places, letting the newcomer ride. In the Non-sharing condition, the occupant turns back and keeps the swing. The design was deliberately chosen because a swing can be used by only one agent at a time, making it an ideal stand-in for a scarce, desirable resource whose repeated monopolization would be hard to depict with hills or slides.

The team then ran four eye-tracking experiments with a total of 103 infants, all around eleven months old and recruited from the University of Tokyo Baby Lab. The experiments crossed two manipulations. The first varied which agent stayed constant across the Sharing and Non-sharing events: in Condition A, the newcomer was the same green sphere-shaped character in both episodes, while in Condition B, the initial possessor was. The second manipulation varied the test phase: in Experiments 1a and 1b, a central agent—either the newcomer or the initial possessor—chose between two characters, and infants’ anticipatory gaze during a three-second window before the choice revealed whom they expected the agent to approach. In Experiments 2a and 2b, infants watched the two agents side by side as third-party observers, with a swing-seat ring lifting one agent upward to signal a positive outcome.

The results were strikingly asymmetric. In Experiment 1a, where infants predicted the choices of a newcomer requesting a turn, their anticipatory gaze lingered significantly longer on the agent who had shared the swing. The difference scores—fixation time on the sharing agent minus fixation time on the non-sharing agent—were significantly greater than zero during the first block of test trials, with a two-tailed test yielding p = 0.016 and a directional test p = 0.008. In plain terms, the babies expected the newcomer to prefer the character that had helped it get a turn. That preference vanished entirely in Experiment 1b, where infants instead predicted the choices of the initial possessor who had been asked to yield. There, difference scores did not deviate from zero in any trial block. And in both third-party experiments, 2a and 2b, no preference for the sharing agent emerged at all, either before or after familiarization.

Statistical modeling reinforced the pattern. Linear mixed-effects models fitted to the gaze data showed a significant main effect of trial repetition but no main effect of experiment, and post hoc comparisons confirmed that the sharing preference in Experiment 1a was confined to the earliest trials. Looking time after the choice was made—the classic violation-of-expectation measure—showed no systematic differences between conditions in any experiment, a limitation the authors attribute in part to the fixed five-second post-choice window, which may have been too brief to capture effects that infant-controlled paradigms typically allow to run longer.

Why would eleven-month-olds reward sharing only when judging from the newcomer’s side? The authors point to the asymmetry built into giving and taking. For the newcomer, the agent who yields the swing is unambiguously beneficial: it removes the obstacle standing between the newcomer and its goal. For the initial possessor, however, yielding means losing playtime on a resource it controls. Prior work has shown that infants use spatial position, body size, and group size to infer social dominance and expect dominant individuals to prevail rather than yield—so from the possessor’s vantage point, holding onto the swing may not register as a moral failing at all. And as neutral observers, infants may simply lack the motivational stake that makes either interpretation compelling.

The team also ruled out a battery of low-level perceptual explanations. If infants merely preferred whichever character was more novel or had spent less time on the swing, then Experiment 1b should have produced an even stronger preference for the newcomer who never got on the swing at all. It did not. Nor could recency or primacy effects explain the pattern, since the structural differences between the familiarization conditions across experiments controlled for those factors. The authors conclude that the infants’ looking preferences are best explained by the socio-moral structure of the taking-turns interaction itself—specifically, who gave and who received.

The findings carry implications well beyond the swing. If early moral preferences are this malleable, the field may need to rethink how it measures them. Rather than asking whether infants are prosocial, the authors argue, researchers should map when and under what criteria these evaluations emerge. Open questions remain: the study tested only eleven-month-olds raised in Japan in a laboratory setting, and the animated scenario isolated a single non-reciprocal episode in which the giver received no gratitude or social reward—unlike real life, where toddlers as young as sixteen months show more happiness when giving than keeping. Whether infants possess an abstract sense of possession that underpins their judgments also remains untested, though prior research shows preschoolers infer ownership from first arrival and control of permission.

What the study does establish is that the seeds of moral reasoning are planted earlier and grow in stranger shapes than the classic helper-hinderer experiments suggested. A baby not yet able to say a single word already understands that the same act—giving up a swing—can look generous from one side of the interaction and costly from the other. Perspective, it seems, is not a skill that develops later in childhood; it is woven into the very first moral judgments humans make.

Subject of Research: Perspective-dependent socio-moral evaluation of sharing behavior in preverbal infants

Article Title: Preverbal infants' evaluation of sharing behaviors within a “taking turns” context is modulated by the perspectives they adopt

Article References: Tian, Z., & Hiraki, K. (2026). Preverbal infants' evaluation of sharing behaviors within a “taking turns” context is modulated by the perspectives they adopt. Frontiers in Developmental Psychology, 4, Article 1904707. https://doi.org/10.3389/fdpys.2026.1904707

Image Credits: AI Generated

DOI: 10.3389/fdpys.2026.1904707

Keywords: infancy, socio-moral evaluation, perspective-taking, sharing, eye-tracking, developmental psychology, turn-taking, social dominance, fairness, resource distribution, preverbal infants, University of Tokyo