Scientists Trained Rats to Associate Certain Odors With Being Tickled

Rats are being tickled for science. The most recent research was a study that found rats can learn to associate an odor with being tickled. A previous study found that rats appear to enjoy being tickled by a human hand so the odor is being associated with a positive experience.

The odor association with tickling study was conducted in June 2019 and led by Vincent Bombail from the INRA Research Center at Jouy-en-Josas. The research paper can be found in PLOS One. Why was this important for science? The researchers found tickling can be used as an alternative positive stimulus to feeding. It also makes it easy for researchers to get close to the rats. They note that the "human hand is used to mimic the tactile stimulation experienced during social play in rats."

Previous research out of Humboldt University in Berlin discovered that young rats vocalize when being tickled. The vocalization was in the 50kHz range which is similar to the vocal range it uses when feeding. Rats even approached and chased the researchers' hands for more tickling in the Humboldt tickling experiments. Rats particularly like being tickled in the trunk region. Take a look:

Image: Vincent Bombail, et. al., PLOS One

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