Should you tell your readers what your characters are thinking? There are several ways to look at this question.
The most common viewpoint nowadays seems to be third-person limited. In this style of writing, the reader sort of lives inside one character’s head, either for the duration of a scene or possibly for the entire novel. We’re privy to that character’s thoughts, but we see the other characters only from the outside. We have to infer what they’re thinking and feeling from what they say and do.
In third-person omniscient, the author feels free to jump from one character’s head to another character’s, freely telling us what each of them is thinking and feeling. This viewpoint is less used today than formerly. It’s not necessarily bad; it’s just unfashionable. Poorly handled, it can rob the story of immediacy. When it’s well done, readers won’t even notice.
In third-person external, the reader is a TV camera. We see and hear only what the camera sees and hears; we learn none of the thoughts or feelings of any of the characters, unless they happen to share them in a conversation with another character. This type of writing can be punchy and effective in a crime novel, but in a thoughtful literary work it may seem very dry.
It’s possible to flip back and forth within a single story. Indeed, some writers jump from third-person to first-person, or from past tense to present tense, quite freely. But again, the fashion in commercial fiction seems to be to adopt one particular type of viewpoint and stick with it.
So let’s suppose you’re planning to use third-person limited. Good choice. However, a hidden danger lurks. You can carelessly tell the reader too much about what your viewpoint character is thinking and feeling. Sometimes it’s better to just get on with the action and let the reader infer what must have been in your lead character’s head.
If you find yourself writing a paragraph in which your lead character debates, silently and internally, about what to do next, loud alarm bells should go off in your head. This paragraph is likely to reveal that you, the author, don’t know what’s going to happen next, and are using the page to work it out:
Dick was usually home by this time. Carol wasn’t sure whether to call his office to ask if he was working late, call the local hospitals to learn if there had been an accident, or let the dinner burn to teach him a lesson.
Don’t do this. Or rather, do it only if it’s thematically relevant — if Carol is prone to dithering indecisively, a trait that is imperiling her marriage. In that case, go right ahead. Otherwise, I would strongly recommend settling for something like this:
When Dick hadn’t arrived home by 6:45, Carol phoned his office, but nobody answered. She decided to let the dinner burn to teach him a lesson.
This gets rid of the author’s thought processes, which very seldom belong on the page.