Why do certain foods or smells elicit emotional responses? Every person has an emotional response to one or more particular foods. The response may be negative or positive depending on the situation that may have occurred with the food present. For instance a person may perk up while smelling coffee or someone may feel nauseated by just looking at a hamburger. These reactions are conditioned responses (CR) toward conditioned stimulus’ (CS) that were previously unconditioned. A conditioned response is a learned reflexive response to a conditioned stimulus. Before someone has the reaction to perk up from the scent of coffee, they first must go through a conditioning phase to associate coffee with feeling energetic. This is also called classical conditioning: the basic learning process that involves repeatedly pairing a neutral stimulus with a response-producing stimulus until the neutral stimulus elicits the same response. The unconditioned stimulus is coffee and the unconditioned response is energy to wake up or perk up for the day. During each morning a person may groggily get out of bed and begin brewing coffee. He or she pours a cup and begin to awaken more from the ingested caffeine. If done on a constant basis that person will begin associating the tastes and smells of coffee (CS) with being energetic (CR); even though the effects of caffeine takes 20 minutes to begin working. Another conditioned response could be feeling nauseated at the sight or smell of a certain type of food. Someone eats a hamburger and a few hours later begins to show signs of having food poisoning. After recovery he or she may associate hamburgers with his or her previously occurred illness and gets nauseated from being near any hamburger. In this case the CR is the feeling of nausea and the CS is a hamburger or possibly any ground meat patties.