If one raven was engaging in object play, another might start doing locomotor play, and still others, social play. “It’s the play mood that seemed to be contagious,” says Osvath. Positive emotional contagion is also found in other animal species—chimps and rats, for instance. Scientists have lately found that negative emotions in ravens can be contagious, too. When a raven sees allies struggle with a task that denies them a treat or sees their disappointment in response to unappetizing food—but not the food itself—its own interest in food diminishes. This kind of emotional contagion, whether
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