A student talks constantly during work time. The teacher rules that the class loses its daily two minutes of free time until they stay quiet for ten minutes, and removes this consequence as soon as the class manages it. Quiet behavior increases. Why?

The honest answer requires a correction to how this book is sometimes read, because the book contradicts itself on exactly this point. Earlier in the book, negative reinforcement is described as though it were a form of punishment, something that decreases behavior. That is backwards, and it is worth being precise about the accepted account rather than repeating the error. Reinforcement, of either kind, increases a behavior. Punishment decreases one. The book's own correct statement of this, later in the book, is the one to hold onto: "reinforcement can be either positive or negative. Positive reinforcement involves providing a reward after the desired behavior is exhibited, while negative reinforcement involves removing an aversive stimulus after the desired behavior is exhibited. Both types of reinforcement can be used to increase the frequency of a desired behavior." In the free-time scenario, nothing rewarding is added, and nothing is taken away as a penalty. An existing restriction is lifted once the class goes quiet. That is negative reinforcement exactly as defined: removing an aversive condition in response to a desired behavior, which increases how often that behavior shows up. Punishment would look different, adding or withholding something unpleasant specifically to make the talking stop; extinction would look different too, simply ignoring the behavior until it faded on its own. This distinction sits inside operant conditioning, the account of behavior shaped by its consequences that is properly credited to B.F. Skinner, not to Watson, whatever a given passage in this book's account of behaviorism might suggest elsewhere.

Term	What happens	Effect on the behavior
Positive reinforcement	Something rewarding is added	Increases
Negative reinforcement	Something aversive is removed	Increases
Punishment	Something aversive is added, or a privilege is withheld	Decreases

Shaping a behavior that barely exists yet

Reinforcement doesn't only maintain a behavior a student already performs; it can build one up gradually. A student who almost never speaks in class has begun raising his hand occasionally, though his answers are usually only a word or two. His teacher praises him whenever he volunteers anything at all, then gradually expects a bit more elaboration each time before offering the same praise. This is reinforcing successive approximations of a desired behavior, what the book calls molding behavior: rewarding each small step in the right direction rather than waiting for the finished skill to appear on its own.

Underneath both examples sits the same underlying distinction the book also draws between intrinsic and extrinsic motivation. Intrinsic rewards are "internal, personal satisfactions one gets from the activity itself, such as enjoyment, interest, or self-expression," while extrinsic rewards are "external incentives or consequences provided by others, such as grades, prizes, or praise." The teacher's praise in the shaping example is extrinsic; the goal, over time, is that the student's own growing confidence in speaking up becomes intrinsically rewarding enough that the external praise is no longer what's driving it.