Scientific Method - Can Plants Learn? (Links to an external site.) Scientists set out to find the answer to the question: "Can plants learn?" Learning is a behavior normally attributed to animals, dependent on a central nervous system to sense and then respond to the environment. In early learning experiments, Ivan Pavlov, showed that dogs could be conditioned to respond to a bell when that bell was paired with a food reward. Every time he rang the bell, the dogs would get fed. Over time, he only needed to ring the bell and the dogs would drool and become excited because they were expecting food. You have probably seen this type of behavior with your own pets; does your dog get excited when he sees you with a leash or hears a can opener? Thatâs because your dog has learned to associate these sounds with some kind of reward, such as food or a walk. The Plant Experiment But how can scientists do the same type of experiment on a plant? Plants seem to have limited senses about the external world. We do observe that plants respond to stimuli. Plants will grow toward light, and their roots seem to know which way is down. Scientists working for space programs must take these behaviors into consideration when developing ways to grow plants in space. These behaviors are not considered learning, they are simply responses to external stimuli. In order to show that plants can learn, scientists would need to design an experiment similar to the one Pavlov performed on his dogs. They knew that plants could respond to light, so the idea was they could pair another stimulus with light, similar to how Pavlov paired food with the ringing of the bell. The experimental set-up included a light and a fan, with a type of tube maze where the plant would grow. The plant could grow toward either side. The plants were "trained" by pairing the light with the wind from the fan. After a training period, the plant was placed in a maze and exposed to just the fan. In most cases, the plant grew toward the fan. It seemed as though the plants learned that if there was a fan, then there would be light in that direction. Video Link: https://www.biologycorner.com/2020/05/19/can-plants-learn/ (Links to an external site.) Answer the questions below in complete sentences (yes, this counts). Submit the answers to the above questions in a separate Word document. 1. What types of stimuli do plants naturally respond to? 2. In the experiment described, what is the independent (manipulated) variable? What is the dependent (responding) variable? 3. What evidence did the experiment provide that plants can learn? 4. The story does not mention a control group. Describe a set-up that could serve as the control group. 5. What is meant by the phrase "learning by association?" Provide an example from this story.