I told Ashlea NO from a young age, and do the same with my 7 1/2 month old nephew who i look after each day for the morning. I think its important esspecially with things like reaching out to play with the heater. He gets told NO even if its not turned on as we want him to learn now not to touch it rather than have him get burned becasue he didn't know.

I agree with Sarah, the shiver or shudder is probably a reaction to your stern voice. Ashlea (5) jumps half a mile if she's doing something she shouldn't and I walk in and use my 'grumpy mum' voice. She hates getting caught!!

Also, like Cailin said, maybe a stern NO for dangerous things, electricity point, heaters etc, but maybe a more gentle 'uhuh' for other things??