Anticipation or being enthusiastic, is an emotion involving pleasure (and sometimes anxiety) in considering some expected or longed-for good event, or irritation at having to wait. Robert Plutchik listed anticipation as one of the eight basic emotions in his psychoevolutionary theory. See also hope. A name for pleasured anticipation is excitement.
Anticipation can be shown in many ways; for example, some people seem to smile uncontrollably during this period, while others seem ill or sick. It is not uncommon for the brain to be so focused on an event, that the body is affected in such a way. Stage fright is a type of anticipation, stemming from the actor or actress hoping that they perform well.
Readers like to anticipate events. Anticipation is the element that hooks into a reader's emotions, taking them alternatively high and low. How does a writer create anticipation?
Dangle an event in front of them, something the character wants (or maybe doesn't want) to happen. It doesn't have to be anything huge, though it might be if the genre calls for it. It could be simple. The only thing it must be is important to the character. For instance, say I want a certain book, so I order it online and wait for it to arrive in the mail. Getting the book in my hands becomes the anticipated event. Anticipation is all about making the character--and the reader--wait. Instant gratification is the arch enemy of anticipation.
A subtle but highly useful method of building conflict into the anticipation is by forcing the character to face a good/good or bad/bad dilemma that actually delays gratification; make the character directly responsible in some way for having to wait. For example, maybe my dilemma was I wanted the book, but I also wanted to save money so I chose the most inexpensive shipping--which takes longer.
To draw the anticipation out while sustaining reader interest, break the anticipated event into stages. These stages build higher and higher emotions in the character (and by extension, the reader). They serve as road signs informing readers who wonder "Are we there yet?" of the story's progress. For instance, the first anticipation stage for me might be checking my email often for a shipping notice.
Tricking the character into false hope or tossing him a red herring is a neat trick, too, and often supplies the next stage. Make him think he's closer to getting what he wants than he actually is. This allows anticipation to rise, then plummet again when he discovers he misconstrued the situation. It's important that the disappointment is organic to the situation, not superimposed by an impersonal fate. It's even more significant if it sources out of a character flaw. For instance, suppose the shipping notice arrives on a Tuesday. I calculate in my head the book will be in my mailbox Thursday. So I eagerly await Thursday's mail. Then, right before the mail is delivered, I get another notice that the book was just shipped. If I'd read the earlier email closer, I'd have realized it was only a notice of intent.
Now the anticipation has to build up all over again, like a roller coaster. One consequence of the previous disappointment is the addition of a new negative risk. The character is not only hoping for something to happen, he's also hoping for something not to happen. For instance, now I'm hoping the book will arrive by Saturday. I'm also anxious that if it doesn't, then I'll have to wait all weekend and won't get it until Monday.
Of course, the payoff of the event ends the anticipation. Stories are generally a series of anticipation-payoff events strung together. As the character's anticipatory tension goes up and down, the reader's anticipation should go up and down with him. Ideally, this encourages readers to turn the pages and keep reading.