Who here has made comments to the effect of “I can’t write good dialogue”? *Counts show of hands*. Yep. Many authors have. There are a few reasons why dialogue can be challenging. Let me give you some pointers using psychology to help develop better dialogue.
Speaking Is Not Writing
The first piece to understand about writing good dialogue is that we do not speak the way we write. When we write, we are searching to create images with words. Therefore, we construct sentences and paragraphs as a visual experience for the reader. Dialogue is like music. It needs to be heard, not seen. So, go out and listen to people talk. Don’t worry about the content of what they are saying. Listen to the rhythm of their speech, the choice of words themselves, and the tempo. Do this for a while. Then try writing some dialogue. Again, when you’re writing it, the content does not matter. Mimic the rhythms and tempos you discovered. Read it out loud. Like I said, dialogue is an auditory experience, not a visual one.
Emotions Matter
When you’re thinking about dialogue, emotions matter. Is the character angry? Chances are, he or she will not be using polite and diplomatic language. Is the character sad? Probably not going to wax on eloquently about something (unless it is a Shakespearean tragedy which is a whole different ball game). How about excited? The speech patterns will be much more rapid than a calm person’s speech. Also, the more emotional the character is, and this holds true regardless of the specific emotion, the less clear the language will be. Now, this is a general rule, but go out and listen to people again. Emotion crowds out more rational thought, which means our ability to string together complex sentences and articulate speeches becomes much more limited.
Gender Matters
No. I’m not saying this because I am a woman or that it is National Women’s Day. It is a 
simple fact that males and females communicate differently. This starts with structural differences in the brain that occur prenatally and builds from there. Don’t believe me? Go listen for a while. Most males will focus their conversation on things they can compete with, concrete numbers and statistics, and physical activities. Most females use communication to connect, to find commonalities, and to build people up. Now, there are always some that defy these gender norms, but as a general rule, this will hold true.
Convincing dialogue is not always easy. Rule change when we switch from descriptive prose to dialogue. Take some time to go out and listen to people. Look for some of the things I’ve shared here about how we don’t speak the way we write, how emotion colors dialogue, and how gender changes the way we speak. Then try your hand, reading what you write out loud.
Part author, part artist, all dreamer 