In literature, as in life, the way people talk to one another can tell you more about their psychological issues than the content of what they’re saying. This is also true of fictional characters. The best writers create satisfyingly realistic characters by consciously and carefully choosing psychologically accurate unconscious word choices for them. These characters don’t just further the narrative with their dialogue; they inadvertently (to themselves, deliberately to the writer) reveal their psychological and emotional shortcomings and/or sophistication through the words they use.
Nowhere is this more true than in the use of “I” statements versus “you” statements in emotionally charged dialogue between fictional lovers, friends or family members.
A character who says “I feel hurt when you don’t return my phone calls” is revealing information on two levels – one, the other person didn’t call them and they were hurt by this; and two, they take responsibility for their own emotional state and are careful about other people’s feelings.
Conversely, a character who says, “You never call me when you’re supposed to, what is your problem? You make me feel so worried, obviously you don’t care about me at all,” is furthering the narrative in the same way as the first (the other didn’t call, the speaker was upset) but they are also telling the reader that they are emotionally unskilled and immature, likely to blame others for their problems and to create needless drama in their lives.
This difference in communication styles is one example of what is meant by “show, don’t tell,” in character development. You could write something like She was clueless about his feelings and always sounded like she was accusing him of a crime when she was upset, telling your reader about the character, or you could write dialogue that shows her doing this.
The reason showing rather than telling is more effective is that your readers will come to your story with their own psychological deficits and strengths, and each will relate to your individual characters in their own unique way. I have been amazed to hear from readers who related most to characters I’d created to whom I’d related the least, or even hated.
In the fiction-writing workshops I give, I often come across writers who, while technically proficient, create characters who feel flat or underdeveloped. These writers could greatly benefit from studying people – whether in a psychology text or in real life, and preferably both.