Operant conditioning is “a process of behavior modification in which a subject is encouraged to behave in a desired manner through positive or negative reinforcement, so that that the subject comes to associate pleasure or displeasure with reinforcement of the behavior” (Dictionary.com). And contingency “refers to the degree of correlation between a behavior and its consequences” (Chance, 2014). Finally, contiguity “refers to the temporal gap between a behavior and its consequences that reinforce it” (Chance, 2014). And the reason contiguity leads to faster learning is that “one of the reasons immediate consequences produce better results is that a delay allows time for other behaviors to occur. This behavior, not contingent behavior, is reinforced” (Chance, 2014). “Dopamine is a neurotransmitter. It is a chemical messenger that helps transmit signals in the brain and other vital areas. Dopamine is present in humans as well as animals, including vertebrates and invertebrates” (2013, Mandal). Dopamine pathways are adrenaline that causes a rush. Dopamine is released when you're on a roller coaster and your heart is beating fast. It's dopamine. According to David Premack, “while reinforcers are usually thought of as stimuli, Premack noted that they can be thought of as behaviors” (Chance, 2014). Still according to the book, “reinforcement involves a relationship, usually between two behaviors, one of which reinforces the other ».”