Final answer:
Robert's negative experience with the Coke machine is an example of operant conditioning where the lack of a desired outcome (receiving the Coke) following a behavior (inserting money) might lead to changes in his future behavior to avoid similar disappointments.
Step-by-step explanation:
Robert's experience of inserting $0.85 into a Coke machine without receiving his beverage or a refund can be understood through the lens of operant conditioning. Operant conditioning is a learning process by which behaviors are influenced by reinforcements and punishments. In Robert's case, his behavior of depositing money into the machine and expecting a Coke is followed by an unpleasant outcome (i.e., not getting his drink nor his money back), which according to the law of effect, may result in a decreased likelihood of repeating this behavior in the future.
This event could be seen as a form of negative reinforcement if Robert's behavior changes to avoid experiencing this negative outcome again. For instance, he might stop using that specific machine or may carry spare change in case the machine does not accept his money. He may even start carrying his own drinks to avoid the potential of the machine malfunctioning. This is because the avoidance of an unpleasant consequence (losing money) is, reinforcement encourages the behavior (not using the machine or coming prepared with alternatives).
Behavioral adjustments such as these reflect Skinner's view on how behavior is shaped by its consequences, and this method of learning can influence a wide range of actions from mundane daily activities to complex decision-making processes like gambling or investing.