There are 25 million to a billion different T-cells in your body. Each cell has a unique T-cell receptor that can fit with only one kind of antigen, like a lock that can fit with only one shape of key. Antigens and receptors work a lot like a lock and key. Each of the 25 million to a billion different T-cells fit with a different shape of antigen.
Motivating operation. Motivating operation (MO) is a behavioristic concept introduced by Jack Michael in 1982. It is used to explain variations in the effects in the consequences of behavior. Most importantly, a MO affects how strongly the person is reinforced or punished by the consequences of their behavior.
Diagram of operant conditioning. Operant conditioning (also, âinstrumental conditioningâ) is a learning process in which behavior is sensitive to, or controlled by its consequences. For example, a child may learn to open a box to get the candy inside, or learn to avoid touching a hot stove. Positive reinforcement (reinforcement): This occurs when a behavior (response) is followed by a stimulus that is appetitive or rewarding, increasing the frequency of that behavior. 2  For example, if a rat in a Skinner box gets food when it presses a lever, its rate of pressing will go up.