 Classical conditioning is a way of learning where a stimulus that triggers a biological response is paired with a new stimulus that then results in the same reaction. The most famous work in classical conditioning was done by Ivan Pavlov in the 1890s. During this time Pavlov did a lot of research around the digestive processes of dogs. One day during his research Pavlov noticed that the dogs began to salivate in the presence of the technician who normally fed them. He wondered if the technician was a trigger that stimulated a response associated with food. To find out he constructed an experiment that would allow him to measure a dog's output of saliva. First he served the dog food. Then he served food while playing the sounds of a metronome and repeated the process a few times. Finally he removed the food and only played the metronome. The dogs began to salivate in response to the metronome alone. Pavlov concluded that if a new stimulus was present when the dog was given food then that stimulus became associated with food and caused salivation on its own. When he published his findings Pavlov called the food an unconditioned stimulus because its effects on the dog were not learned. Instead they triggered an unconditioned response that happened naturally and completely out of the dog's control. The metronome is at first a neutral stimulus. Through the process of repetitive pairing with food the dog learns to connect the two. This means that the neutral stimulus becomes the conditioned stimulus and the response to that a conditioned response. He also reported that 1. Learning occurred most rapidly when the interval between the sound and the appearance of the food was short. 2. The saliva produced by the sound differed in composition from that produced by the food which means that the conditioned response was not an exact replica of the unconditioned response. 3. While there are several forms of conditioning such as forward and backward conditioning classical conditioning cannot create new behavior or be used for training but instead triggers involuntary biological responses. 4. We can almost entirely undo the conditioning. This happens through extinction when we repeatedly present the conditioned stimulus in the absence of the unconditioned stimulus. So what occurs inside the brain? When a dog sees the food the signals from the eyes and nose stimulate the brain which activates the salivation glands to secrete saliva to aid the dog with the digestion. When a dog hears a sound the ears send a signal to the brain which takes note but has no reason to activate anything. When the two different neurological processes are being activated simultaneously new synaptic connections occur between the auditory stimulus and the behavioral response. Over time these synapses are strengthened so that it only takes the sound to activate the pathway leading to salivation. You can try this popular classroom exercise. Take a friend, sit down and relax for two minutes then allow your partner to check and record your pulse rate. Your partner will then tap a pencil on the desk five times. Right after stand up and hop on one leg for 30 seconds and then check your pulse again. Repeat the procedure four times having the partner record all data. After relaxing for the fifth time your partner will tap the pencil five times as usual. Now instead of getting up for your exercise only check your pulse. If the conditioning was successful your pulse rate will rise even without engaging in exercise. What do you think? Does classical conditioning always work? If so our commercials are form of mental manipulation and should we limit advertising in public spaces. Sprouts videos are published under the Creative Commons license. That means our videos are free and anyone can download, edit and play them for personal use. And public schools, governments and non-profit organizations can also use them for training online courses or designing new curriculums. To help us stay independent and support our work you can join our patrons and contribute. Just visit patreon.com slash sprouts even one dollar can make a difference. If you have deep insights into academic topics and want to help us explain complicated ideas in simple language please contact us at sproutsschools.com