OK, that is standard of lying that is still consistent with Pervasive Developmental Disorder (PDD) - she is desperately trying the "I didn't do it" route even in the face of obvious evidence to the contrary.
Now, think about this from the vantage point of inside her head. Forget your own anger at her, forget that you are her parent (for a few minutes). Now you are in her head as an impartial observer. Try to plug in to her level of emotions.
She is impulsive - she wanted the black nails for some reason. How can she get this fast, while she wants it?
OK, Mommy has black nail polish. But it's not mine, it's Mommy's. But nail polish goes a long way, she won't miss any in the bottle and if it doesn't get used it eventually goes yuk in the bottom of the bottle anyway, I may as well have some on my nails.
The wanting overwhelms the "this is against the rules". So she goes and does it, figuring it will be on and dry, when you eventually notice it she might say she borrowed a friend's nail polish bottle. [and for the mom in you sneaking peeks out - another way to check if it's been freshly applied, is to look for smudges on the skin. I find it takes about a day for them to wear off, even the best-applied nail polish]
Now she has done something she shouldn't have, because the desire to do it was greater than the desire to not do it. So far, fairly typical.
But she has done the wrong thing. Her anxiety is climbing. Her biggest anxiety now is, "I have broken the rules". This is a good thing, in that it is something that she is aware of and finds upsetting, even a little bit (obviously not enough to overcome these impulses!).
Then in comes Mom like an avenging angel. Mom knows everything. well, most everything. Mom knows that something is wrong.
She is afraid to confess, because her anxiety is now greatly ramped up to such heights that she can;t think properly, can't plan. Her best way out, to help her anxiety stay as low as possible THIS MINUTE, is to lie and say, "I didn't do it." This is the simplest lie in the world, the instinctive lie, the one that just about anybody can tell.
Depending on the questions asked by the interrogator, the lie can become more complex, often with help. Imagine an interrogator asking, "Did you get this from your friend?" Often in the face of noonsensical impossible denials, we try to find the truth by asking leading questions. It's the worst ting to do with a Pervasive Developmental Disorder (PDD) kid because in doing so, you are letting thme know that there ARE alternative explanations you might be more inclined to beelive, and you are also handing some of these options to the child on a silver platter.
You did this well by going over the logic of the situation and showing her that her lie did not make sense. NEVER give her any alternative possibilities. She may think of some herself - follow the logic.
But tihs has come from, beleive it or not, a basic law-abiding nature coupled with exrteme anxiety when she fears she is being found out. Her anxiety is so extreme that telling a lie is the better option than telling the truth - telling the truth here is making her more anxious because for her, being caught in a lie is so very upsetting, so very shameful. Her tears at this point are genuine.
So what I suggest you begin to do (and it may sound crazy) - comfort her when she admits the truth or when it has reached a point where you obviously know the truth anyway. Continue to comfort until after she has repeated the truth to you. Comforting her in a way that she recognises as comfort, can help reduce the anxiety. You need to build up a conditioned response where she associates telling the truth (even to replace a previously-told lie) as being the best and fastest way to reduce her anxiety.
At the moment, it's a hump she can't get over. She acts on impulse, breaks the rules, then because she is now feeling anxious about getting caught in a lie or transgression, she continues to lie and make it worse.
Try to not get angry (not openly). Being disappointed in her should work better, but she also needs to know you love her anyway. But truth is more important.
Now the next prong in your attack - ask her why she wanted black nails. If this is against her rules, tell her why. Now together, try to find a compromise. Can she wear black nails at home around the house but not to school? Maybe she could put on black nail polish on Friday nights and take it off on Sunday night. Or maybe the rules need to be reconsidered now she is older.
Of course she needs to keep her hands off your nail polish but allowing her to earn her own bottle of nail polish could be an incentive you could use.
The most importnt ting is to keep the communicaiton open. You have laid down some very strong groundwork on the rule-following and not telling lies, but her continuing impulse control issues are getting her into constant trouble with this and the anxiety she feels is greater than for TTs. That is why I think you are getting these paradoxical findings.
we had a horrible time with difficult child! when he was in his early teens - he wanted stuff. He has always wanted stuff. But he was stealing money from my wallet to buy it, then lyingg about it to say his friends had lent the stuff to him or he'd swapped stuff. He couldn't maintain those lies for too long, but it was long enough to cost me hundreds of dollars.
What turned him around? None of the "you know you shouldn't steal, you know you shouldn't lie..." - he already knew tat and his anxiety was so ramped up he had dug himself into a hole he couldn't get out of.
What turned him around - I burst into tears. It was genuine. I sobbed, loudly, that my son had become a thief from his own mother and a liar, and that was wounding me so deeply. I also made the point that often the money he took was money I may well have spent on him anyway (for tings like new shoes) but had to change my mind when I found myself with less than I thought I had. Or we had perhaps had to go short of food that he likes and eat more of my "gourmet poverty food" which meant that hewasn't just stealing from me, he was stealnig form the whole family, including himself.
I was really upset, inconsolable. husband took over while I left the room. I don't think he scolded much, just pointed to my retreating back as "Exhibit A".
difficult child 1 never stole again. But he would come to me wanting stuff and ask my help in finding ways to earn the money.
We had balanced his burning desire to own stuff (which took a long time to help him understand, our materialistic society and advertising always makes these things seem not only within your reach, but something you are entitlted to have) with his anxiety levels and his need to tell the truth and not break the rules. What we had to do was find a way to remove the hump of anxiety than can sometimes get in the way of our kids coming back to the right side of the tracks.
difficult child 1 is really bright, but some concepts just took years longer to sink in. I think there's still a lot of room there for more. Life is a learning experience, life-long. and back then he really couldn't equate the "you ought to be congratulated (for choosing to buy Brand X)" with the reality of, "We don't need to own everything we want or desire, life is about making choices." Also, advertising is about lies. They lie to us. And they're good at it. Pervasive Developmental Disorder (PDD) kids are not good at it. We understand lies. Pervasive Developmental Disorder (PDD) people try to, but don't get lies on the same level.
And that is another big thing - we find this with easy child 2/difficult child 2 especially - making choices. My favourite author, Terry Pratchett (in "Wee Free Men" - a book I can highly recommend to your daughter and to you - it's fantasy satire, would appeal to latent Goths who need a moral compass, and their families) refers to this as "tragic sweet deprivation".
The story is - Tiffany's baby brother Wentworth has been stolen away by the Queen of the Fairies. The Qeen is evil - she gives you everything you want. And this is not always good for you. Tiffany finds her baby brother (who she doesn't really like much because he's so sticky, but her mother loves him and wants him back) sitting on a large flat stone surrouded by sweets. Everything imaginable, brightly coloured, sugar-laden. And he was sobbing, crying the way babies cry when they are really, really upset (some good description we would all really get!). Story continues:
"Tiffany knew what the problem was immediately. She'd seen it before, at birthday parties. Her brother was suffering from tragic sweet deprivation. Yes, hewas surrounded by sweets, but the moment he took any sweet at all, said his sugar-addled brain, that meant he was not taking all the rest. And there were so many sweets he'd never be able to eat them all. It was too much to cope with The only solution was to burst into tears.
The only solution at home was to put a bucket over his head until he calmed down, and take almost all the sweets away. He could deal with a few handfuls at a time."
With easy child 2/difficult child 2, this problem with choices is very similar - it could be two unpleasant choices, or two enjoyable ones. You would expect anxiety with two unpleasant choices. But with the choice between chocolate chip ice cream and strawberry ice cream? She can only have one, whichever she chooses she kows she will enjoy. But to choose one is to say no to the other, and this she cannot do. The anxiety ramps up and up until often someone else has Occupational Therapist (OT) make the choice for her. Of course, this absolves her form personal responsibility for the choice, so if the ice cream tastes horrible, for example, she can blame the other person. As you can see, it's not healthy for her to allow other people to make her choices because she is allowing her anxiety to rule her life.
Remember, easy child 2/difficult child 2 does not have an Asperger's diagnosis. I think she should have, but it would only be mild. But the traits she does have (diagnosed) can be quite crippling sometimes. And the trouble with lies and anxiety as a combination when they're allowed to fester - they can become a lifelong habit of self-denial, of not admitting to yourself what the real problem is, because then you would have to face insurmountable anxiety. So you learn to accept the reality that causes less anxiety.
Not good. Must be nipped in the bud.
difficult child 1 is now the extreme law-abiding honest citizen. His church loves him. From what I know of him and church attendees in general, I don't think they fully realise just what they have - a person who really does follow all commandments strictly (including not jaywalking, not taking a serviette with his meal from the fast food place if he already has a serviette in his pocket and who is also scrupulously honest. To a fault. And expects the same standards from those around him.
If someone had told me this about him ten years ago, I never would have believed it possible.
Marg