Misunderstood: The Ticklish, Empathetic, Laughing, Problem-Solving, Chocolate-Sharing Rat

Rats are social creatures.

In just a few days, my family will be welcoming some new pets in the form of three young rats. We have been planning for them for about a month now, and my kids and I are getting excited (the jury is still out on how my husband or our cat feels).  The response we get when we share the news with friends and family members has been wildly varying. Some can barely repress their shuddering as they ask why on earth would we want rats?? Others will go on and on about the cool rats they have owned or known and share humorous anecdotes about their furry friends.

The difference in opinion is striking. One group sees these creatures as horrid, filthy, vicious, disease-carrying vermin; while the other sees them as intelligent, social, affectionate companions. As a scientist in the lab, my experience with rats was limited to comparing the sequences of rat and human nicotinic acetylcholine receptors (they’re not all that different it turns out), but the more I read, the more I begin to think that rats have been terribly misunderstood. Mind you, I don’t mean that I have been reading Rat Fancier or some other rat enthusiast publication (not that these are bad sources of information). No, I am a scientist and when I want information, I go to the literature, and what the scientific literature says about rats is really quite fascinating.

Rats Laugh When Rough Housing and Like to be Tickled

In the mid 1990s, Dr. Jaak Panksepp and Dr. Jeffrey Burgdorf made an amazing discovery about the rats they used in their lab. When wrestling or playing, young rats made a high-frequency, ultrasonic chirping noise. The noises were outside the range of human hearing, but the researchers were able to record them using a special device normally used to listen to bats. When they used their hands to play with and “tickle” the rats, the vocalizations increased. In fact once the rats associated a hand with this type of play, they would eagerly chase after it. Following a series of experiments, Panksepp and Burgdorf concluded that what they were recording was in fact rat laughter and that the rats liked to be tickled and in fact would actively seek out a hand that had tickled them in the past.

Although their early attempts to publish their findings were met with stiff resistance, they have gained some acceptance of their theory (1-3) beginning after their presentation at the Toward a Science of Consciousness III Conference in Tucson, AZ in April of 1998 (4). They also attracted the attention of the popular press including People magazine and made appearances on some television shows. You can see (and hear) Dr. Panksepp and his laughing rats on YouTube, here:
[youtube http://www.youtube.com/watch?v=j-admRGFVNM]

Like Humans, Rats Combine Sensory Cues to Make the Best Decision

Most people will agree that rats can be clever. Most of us have seen or heard about rats that learned how to find their way through complicated mazes or figured out how to let themselves out of their cages in the middle of the night. But does this mean that they are capable of actively processing information from multiple sensory sources to make a decision? According to a group of researchers from Cold Spring Harbor Laboratory, the answer is yes. In a study just published in the Journal of Neuroscience (5), Dr. Anne Churchland and her colleagues found that rats’ ability to assess a situation using multiple senses and make the “statistically optimal” decision was just as good as humans. By this they meant that the rats used the information from different sensory stimuli (auditory and visual) in the most efficient and unbiased way.

What was most interesting to me was that although the signals from these two senses probably reach the brain at different speeds, it appears that the rats were able to process the information from each sense separately and then fuse these pieces later to make the final decision. This ability to optimally combine stimuli from multiple senses is well-known in humans, but much like laughing, many scientists have been skeptical that it occurs in other species. By studying this ability in rats, we might be able to learn more about how humans process sensory stimuli.

Rats Will Help a Cage Mate Even if it Means They will Have to Share Their Chocolate

Rats are social creatures. They live, eat, play and sleep in groups. They also behave in a pro-social manner— that is they act in a manner that benefits another. An example of this behavior is described in an article in the December 9 issue of Science (6). Rats were placed in an arena along with a container that held a cage mate. The restrained rat could be freed if the other rat put enough pressure on the cage door to tip it open. The loose rat spent significantly more time around the container that held its cage mate and learned to open the door within about a week (6.9 days). Because it could be argued that the liberating rat was gaining a reward in the form of a playmate, the conditions were changed so that the freed rat could not interact with the liberator after it was freed. The rats continued to open the door, even though they could no longer play with their cage mate once freed. In contrast, when the rats were placed in an arena with an empty container, they quickly stopped opening the door.

Then came the real test of pro-social or empathetic(?) behavior. Rats were placed in an arena with a trapped cage mate and a container with chocolate chips. The rats liked the chocolate chips, but still showed no change in how fast they released their cage mates. In fact (this is the part where the rats just might beat my kids in pro-social behavior) the rats not only freed their cage mates, they also opened the container with the chocolate chips and only ate some, leaving the rest for the freed cage mate. In the control group consisting of single rats in arenas with containers of chocolate chips, the rats ate all the chocolate chips.

Happy with Our Choice

After watching the rat tickling video, reading all these papers and reading several rat care books, I am convinced that we have made a good choice in deciding on rats for our kids’ new pets (okay, one rat might be for me). I am looking forward to learning more about these incredible creatures. And I am relieved to know that if they get into the cookies they’ll probably leave some for us.


  1. Panksepp, J. and Burgdorf, J. (2003) “Laughing rats and the evolutionary antecedents of human joy? Physiol. Behav. 79 533-547.
  2. Panksepp, J. (2007) Review: Neuroevolutionary sources of laughter and social joy: Modeling primal laughter in laboratory rats. Behav. Brain Research. 182, 231-244.
  3. Panksepp J. and Burgdorf, J. (2010)Laughing rats? Playful tickling arouses high-frequency ultrasonic chirping in young rats.  American Journal of Play Winter 2010, 357-372.
  4. Toward a Science of Consciousness III Tuscon Conference (accessed March 26, 2012) http://www.scribd.com/rclark7083/d/4787606-Toward-a-Science-of-Consciousness-III-Tuscon-Conference 
  5. Raposo, D. et al. (2012) Multisensory Decision-Making in Rats and Humans. J. Neurosci. 32, 3726-3735.
  6. Bartel, I. B-A., Decety, J. and Mason, P. (2011) Empathy and Pro-Social Behavior in Rats. Science 334, 1427-1430.
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Kelly Grooms

Kelly Grooms

Scientific Communications Specialist at Promega Corporation
Kelly earned her B.S. in Genetics from Iowa State University in Ames, IA. Prior to coming to Promega, she worked for biotech companies in San Diego and Madison. Kelly lives just outside Madison with her husband, son and daughter. Kelly collects hobbies including jewelry artistry, reading, writing and knitting. A black belt, she enjoys practicing karate with her daughter as well as hiking, biking and camping.


  1. watch out for GMR! get more rats. lol. i started off with 2 boys in november 2008 and now i have 29 boys. over the 3 years ive owned 51 boys. they are very Moorish, intellegent, loving and mostly monsters who know what they want and how to get it.
    welcome to the world of owning rats. .

  2. Thanks for the warning Devon! So far they haven’t done that but most of the time they are too busy chasing each other and figuring out ways to escape from their large “play pen” to hang out and be tickled.

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