After winning the Nobel Prize in Russia for his work on the digestive system, Ivan Pavlov changed course when he accidentally observed a form of learning through the acquisition of associations to late 19th century (Myers). Pavlov observed a dog salivating when food entered its mouth; he also noticed that the dog did not salivate only with the taste of food, but with the sight of food, or with other stimuli that preceded the food. Pavlov decided to introduce a tone, this new stimulus caused an observed oriented reflex and the dogs turned their heads and their ears stood up (teacher). After observing how the new stimulus attracted the dogs' attention, Pavlov realized that after a while the dogs lost interest. Why Dogs In Pavlov's model, he tested his theory by first introducing a neutral stimulus. Pavlov chose a tone as a neutral stimulus. Pavlov chose the tone because it had nothing to do with food. He would make this connection as follows: He matched the tone (NS) to the food (US). Food is the unconditioned stimulus, because food is the reflex stimulus that automatically triggers salivation. After the first test, the dogs salivated, and Pavlov classified the salivation as an unconditioned response (UR), since food intake naturally produces salivation. Ivan Pavlov continued to pair the NS with the US and in each trial introduced the tone, paired it with food and received a salivating model from Pavlov's paradigm, the neutral stimulus in the advertisement is the Covergirl brand. The sensuality and beauty of Katy Perry, famous singer and face of Covergirl, serve as an unconditional stimulus (USA). Combining the brand with the sensuality and beauty of Katy Perry, Sarah would like to purchase mascara, which Pavlov called the unconditional response (UR). The concept of beauty will naturally evoke an unconditional response (UR) with the urge to purchase the product. Who doesn't want to look good? Whenever Sarah comes across this advertisement, she will associate the Covergirl brand with beauty. After several pairings, Sarah purchased the mascara when exposed to the brand. As soon as Covergirl begins to provoke the purchase of mascara, the brand switches from the neutral stimulus to the conditioned stimulus, producing a conditioned effect.