Sometimes children lie -- because they're afraid.
Sometimes children lie because they have become afraid of the person they are lying to.
If you think your child is experimenting with lying, begin by writing down every time you observe it happen. What situation did it appear in? What brought it about? You can also keep a chart. You may begin to discern patterns.
When you address the child, if they respond with an expression of "I don't care" or of simply not caring to try to be truthful, try backing away a bit to see if something else is going on. Sometimes tweaking the way we correct a situation may help.
- Is the child understanding? Sometimes children have a slower processing of words.
- Is the child afraid?
- Is the child holding their emotions in?
In thinking about the discipline, it is not about becoming more harsh. It is more often about a need to become more creative. Find the way to teach the child in a way they can get it -- in their language, so to speak. Try to understand what is going on inside their head and heart. Even pray, asking God for creativity.
Some children learn character qualities such as truth from stories. For example, Crying Wolf, Aesop's Fables, etc. Some games might promote moral character. For instance, Shoots and Ladders, where if you lie, cheat, or hurt someone you slide down the shoot.
Rather than immediately trying to stop everything that bugs us or worries us about our child, ask God what he is working on in them at that time. (For those of you who include prayer as part of your life.)
Think about age-appropriate work. Work on what it is time to at that moment. Not everything all at once.
For further reading, Kirby recommends John Haidt.