Samantha has become a compulsive liar here lately. She lies about absolutely EVERYTHING!! I dont know what to do to get her to tell the truth. For example this morning: I told her to go brush her teeth, she goes in the bathroom and comes out in the kitchen and throws her toothbrush away, although she didnt know that i was watching her. Then her big sister walks in the room and Samantha says, "Somebody threw my toothbrush away mommy," I sat there in silence. I couldnt believe what she just did, and then lied about it. I told her that she threw it away because she thought shed get another toothbrush ( i bought some new ones). And she still continued to lie to me, saying she didnt do it and that someone else did. Then i told her that i seen her do it, and she had that "UT OH, IM BUSTED" look on her face. Then i asked her why she lied, and she said, "i didnt wanna get in trouble mommy", i told her that she gets in trouble for not telling the truth, rather then telling the truth. I told her that all she had to do was tell me she needs a new toothbrush, and i would have given her one. I dont know what to do with her lying. She had like four incidents yesterday with lying, and it even got her sister in trouble, because she convinced us she didnt do it that her sister did. What do i do about this lying?? What is a reasonable punishment? I told her that she couldnt have computer time tonight or have her three snacks. Is that going too far. They get three snacks a day in between meals. Should i ground her to her room all day? I dont know what to do. What would you do?

we have the marble jar (rewards and consequences) and whenever she lies, she loses a whole bunch of marbles from her jar.

Lying is pretty commonplace around here too as they try it out. But I've learned that if something doesn't sound right - its usually a lie and I can detect them before even verifying (like checking the garbage)

I'll ask "did you flush the toilet?" (knowing full well they didn't because I didn't hear it). They'll tell me yes. I'll tell them "think about your answer carefully. Tell me the truth, not what you think I want to hear. Because if you lie, you'll get in double trouble."

Now that they've been being caught and the marbles are taken away, they are deciding it's better not to lie and just tell the truth. But it's a long process and one that they have to realize on their own

That is a pretty good idea. How do you actually do that. I mean if she has so many marbles does she get a reward, and if she loses so many marbles there is a consequence?

My girls body language gives away their lies. I also told them that Mommy's have a special 'power' to know when they are lying.
We went through this with Julia. I was really hard on her because everything coming out was a lie and it was so obvious. I ask her the first time what happened after the lie ... then I tell her this is your second and last chance to tell the truth and tell her what will happen if she doesn't. I take away major privileges in our house. First, no TV for a day, then no computer then no sweets/junkfood. After those are used up then we tack on days. It hit her so hard that lying is basically done here. Little white lies/teasing still is here but it's nto as bad and it's usually done like a joke (like she burps and blames kaitlyn) .

the marble jar is for everything. Doing good things, doing bad things... when the marble jar is filled, she gets a reward. (and you can tailor it to each child. Sarah's is when its filled, she gets to go to chuck-E-Cheeses, for Andrew he gets to buy himself a Star Wars action figure pack (about $15), some people just give their kids the cash and let the kids decide what it is etc... whatever their heart's desire is is what the reward should be.)
so to fill the marble jar (which is quite large) it takes many many months. especially the way my kids misbehave
they get marbles for flushing the toilet and turning out lights. For washing hands - for good manners (when I catch them doing it without being prompted), for getting dressed without me telling them to, for making their bed, etc...
they lose marbles for lying, hitting, not eating their dinner, swearing (or potty talk), etc.

you have 2 jars - one is the 'in' jar, and one is the 'out' jar. all the marbles but 10 to start with are in the 'out' jar. You work on filling the 'in' jar.

its VERY effective if you stick with it and remember to use the tool yourself.