Hassett · Hormones and behavior 2008 · observational animal behavioral study · n=34

Sex differences in rhesus monkey toy preferences parallel those of children.

Cited 220 times in the scientific literature.

Level 5 - mechanism / opinion, no new human data

Oxford Level 5: animal research study

PubMed 18452921 · doi:10.1016/j.yhbeh.2008.03.008 · record verified 2026-08-26

What was done

Interactions with human wheeled toys and plush toys were observed and compared in 34 rhesus monkeys living within a 135-monkey troop to test whether sex-typed toy preferences emerge in non-human primates without human gender socialization.

What was found

Male monkeys showed consistent and strong preferences for wheeled toys, while female monkeys showed greater variability in preferences. The magnitude of preference for wheeled over plush toys differed significantly between males and females. The abstract reports no numerical values, interaction durations, or test statistics.

Why it matters

Demonstrating sex-differentiated object preferences in non-human primates suggests that biological biases, rather than human social conditioning alone, may contribute to sex differences in toy choice.

Limits

This is an animal study with a small sample of 34 subjects from a single troop, limiting direct generalizability to humans. The abstract does not report quantitative measurements, exposure durations, exact p-values, or direct hormonal assays.

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