Y: Don, do you remember Pavlov’s experiment with dogs?
D: Yes, I do, Yaël. Pavlov was a Russian psychologist who studied learning. He found that when he showed his dogs meat before feeding them, they salivated. Next he tried always ringing a bell before bringing the meat. He found that, after a while, the dogs would salivate if they just heard the bell. They had learned to associate the bell with food. This ‘associative learning’ has been shown in lots of different kinds of animals.
Y: In 2016 an international team of researchers published evidence that plants have associative learning too.
D: Yaël, this isn’t April Fool’s Day. Be serious.
Y: I am serious. Just as dogs like meat, pea plants like light. The researchers grew pea plants in Y-shaped tubes. The plants could grow into either arm of the ‘Y’. During a series of training sessions plants were exposed to light through one of the two arms. Which arm was lit varied on a planned schedule. Each time a fan always blew from the same arm, or always blew from the opposite arm from the light.
D: I see. The fan is just like Pavlov’s bell.
Y: That’s right. The researchers then left the plants in complete darkness with a fan blowing into one opening of the tube. The experiment showed that, just as Pavlov’s dogs learned to associate the bell with food, the plants learned to associate the fan with light, and use it as a cue to determine which arm of the ‘Y’ to grow into.
D: So, if the researchers are right, plants can learn associations!