Laughing Rats? Rats are sociable, playful creatures. They emit distinct, high-pitched chirps when they play, anticipate treats, and during positive social interactions. They also chirp when they’re tickled by researchers like neuroscientist Jaak Panksepp (2000, 2007). But when infant rats are separated from their mothers, or when they’re cold, they emit a distress cry that is much lower in frequency than the ultrasonic chirps that are associated with pleasant experiences.

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