Do Rats Laugh? Tickling Studies and Rat Emotions

Panksepp and the discovery of rat laughter

The idea of laughing rats comes mainly from the American neuroscientist Jaak Panksepp (1943–2017), a founder of the field he called affective neuroscience. In the late 1990s, Panksepp and his student Jeffrey Burgdorf noticed that young rats made many ultrasonic calls during rough-and-tumble play. They wondered whether imitating that play with their hands would produce the same sounds.

It did. When researchers “tickled” young laboratory rats by quickly rubbing their bellies and the backs of their necks, the rats produced bursts of 50 kHz chirps. They chased the tickling hand, came back for more and quickly learned to approach the person who tickled them. Panksepp and Burgdorf published a series of papers around 2000–2003 arguing that these chirps resemble a primitive form of laughter.

What does rat laughter sound like?

Brown rats, including pet and laboratory rats, use two main families of ultrasonic calls:

Human hearing reaches only about 20 kHz, so both types are usually inaudible to us. To listen, researchers use special microphones or bat detectors that shift the sounds down to an audible range. On a recording, the 50 kHz calls sound like rapid chattering, while the 22 kHz calls are longer and more monotonous.

What tickling studies show

Several findings suggest that tickled rats are genuinely enjoying themselves rather than just reacting to touch:

• Rats work for tickling: they press levers or run to a hand that tickles them.
• Young rats chirp more than adults, matching the fact that play is most common in youth.
• Rats tickled regularly become calmer and easier to handle.
• Tickling a rat that is already anxious produces far fewer chirps.

That last point was tested in a 2016 study in Science by Shimpei Ishiyama and Michael Brecht in Berlin. Rats were much less ticklish when placed on a raised platform under bright light, conditions that make them nervous. The researchers also found nerve cells in the body-touch area of the rat brain that fired strongly during tickling and even when the rats were about to be tickled. Some rats made sudden, joyful-looking jumps, which the team compared to the leaps of playful young animals.

Ear color and posture give extra clues. A 2016 study from the University of Bern found that tickled rats held their ears more loosely and that their ears turned pinker, signs the authors linked to a positive emotional state.

Hide-and-seek: playing just for fun

In 2019 Annika Reinhold, Michael Brecht and colleagues in Berlin taught rats to play hide-and-seek with a person in a large room. The rats learned to take turns as hider and seeker, stayed quiet while hiding and chose opaque boxes over transparent ones. They were rewarded not with food but with tickling and play.

The rats chirped excitedly while seeking and when found, and some jumped for joy. The study suggests that rats can play by rules for the fun of it.

Is it really laughter?

Rat chirps are not the same as human laughter. People laugh with rhythmic breathing and voiced “ha-ha” sounds, often at jokes, while rats chirp in short ultrasonic bursts during physical play. Panksepp himself argued only that the two share deep evolutionary roots in mammal play.

Other scientists urge caution. A 50 kHz call can also signal excitement or a wish for social contact, and some calls of this type occur in situations that are not obviously happy. Most researchers agree, however, that the chirps are a reliable sign of positive arousal in rats.

Rats are not alone. Great apes make breathy, laughter-like sounds when tickled or playing, and a 2021 review counted play vocalizations in at least 65 species of mammals and birds. Some animals that seem to laugh, however, are doing something quite different; spotted hyenas’ giggles, for example, signal frustration or submission in tense moments, as explained in why do hyenas laugh?

What this means for rat emotions

Studies of rat laughter have helped change how scientists think about animal feelings. They show that a small rodent has measurable positive emotions as well as fear and pain. As a result, some laboratories now use gentle tickling to help rats feel less stressed when handled, as part of good animal welfare practice.

For more about the species behind these experiments, see the brown rat profile, and for what rats can learn and remember, read how smart are rats?